Leica 50mm Summilux f/1.4 lenses

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The workhorse of Leica lenses:
The 50mm Summilux-M ASPH f/1.4

The Leica 50mm Summilux-M ASPH f/1.4 (2004) is the lens that suits the Leica M the best in terms of design and proportions. It also happens to be a unique masterpiece of lens design that reflects the core qualities of a Leica lens. A versatile workhorse for the photographer.

Petit Palais in Paris. Leica M11 with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

The Leica 50mm Summilux-M ASPH f/1.4 (2004) in chrome and black on the Leica M9-P (2012). It's the most harmonic lens combination for the Leica M in terms of industrial design. © Thorsten Overgaard.

Hong Kong. Leica M9 with 50mm Summilux-M ASPH f/1.4. © Thorsten Overgaard.

An understated favorite lens of mine

Once I included it in my lens arsenal, I found it useful for cetain projects. For certain occasions I would pick the 50mm Summilux-M f/1.4 ASPH for a job. When I visited the White House, this was the lens I brought because it was compact and didn't look like anything. The invitation had stated, "no professional cameras", which definitely ruled out big-looking cameras. So I tried to look compact (and it worked).

At the White House Christmas Party I decided for a discrete camera as "no professional cameras" were allowed. Leica M10 with Leica 50mm Summilux-M ASPH f/1.4. © Thorsten Overgaard.

Looking back at recent years, when I photographed the Clive Davis Grammys Gala, this again was the only lens I brought. Simply to be able to move quicky while taking photos with an artistic narrow depth of field at f/1.4, yet have clarity and details. Ideally, I wanted to move around like a guest without getting noticed for my camera.

John Legend at the Clive Davis Grammys Gala. I'm almost resting the camera on his knees. Leica M10-P Safari with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

When I photographed my daughters wedding, this too was the lens I brought as my main tool, for the same reasons as above. To be able to move, but to get the photos I wanted, with an artistic look, in high quality.

My daughter's wedding. Leica M240 with Leica 50mm Summilux-M ASPH f/1.4. © Thorsten Overgaard.

The reason it took me so long to love this lens

For the longest while I had to force myself to put it on the camera, because I always felt that the result of it was given. "Unsurprisingly good pictures", if that makes any sense. While many around me in my workshops used the Leica 50mm Summilux-M ASPH f/1.4, it never appealed to my heart, even despite the fact that from the moment I first saw it I knew it was a masterpiece of lens design. In terms of industrial/optometric design, it is the best harmonic for the Leica M.

Leica M10 Monochrom with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

The version I got for myself was the limited edition in the 1959-design barrel, but with the 2004 lens design. It's the one called Black Chrome, because it is brass with matte chrome paint on it. Over time the black paint wears off and the brass shows.

In many ways, it doesn't make sense that I got the heavy model when I admire the original industrial design so much. But well, that's how it went down. And as the weeks had gone by, this lens had grown more and more on me.

I could have it as my one and only Leica lens if I wanted to pretend I was going to an island and could only bring one lens.

Tebogo Louw. Leica M10-P Safari with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

The definition of a Summilux lens

The Leica 50mm Summilux-M ASPH f/1.4 is rather special because it is a 2004 lens design that sets the standard for all Leica lenses today. With small size and few means it delivers a very stable image.

It is a departure from the low-contrast, soft-but-detailed Leica look that seems to have set the tone for great photography of the 1950's, 1960's and 1970's photography when it was at its best. That "Leica look" was designed by legendary lens designer Dr. Mandler, who was the lead lens designer and CEO of the Leitz/Leica factory in Canada back then.

Classic 1960's soft but detailed
Elise Lou by Thorsten Overgaard. Leica M9 (2009) with Leica 50mm Summicron-M f/2.0 II (1956)		Katharine Hepburn

I am a big fan of classic photography. In fact, when I really like one of my own photographs, it has a look of the 1940's or 1960's or some undefined "good old days". The soft-but-detailed Leica look, along with a softer contrast, is an essential part of that look of past times.

What happens to the photograph when performed with the higher contrast, more clarity and more detailed, like what the Leica 50mm Summilux-M ASPH f/1.4 delivers, is that it's elevated to what could best be compared to the classic large format photographs. When done in the studio, these often had high contrast and much detail.

As this lens has grown on me, I have become accustomed to the new look this lens presents, and as we look around, most lenses have gotten increased contrast and detail level. Some too much, but that is not the case with this one.

Leica 50mm Summilux-M ASPH f/1.4. © Thorsten Overgaard		Elizabeth Taylor

An artist's brush

What makes the Leica 50mm Summilux-M ASPH f/1.4 special in the range of lenses, are its artistic qualities. First off there is the f/1.4 aperture that is optimized to be used wide open at f/1.4. Not many lenses are optimized to perform their optimum at their widest aperture. In most lenses, a "low light" wide open aperture is often added for the possibility of making photographs in low light - with an implied loss of quality because it's so difficult to control the light in a wide open lens.

With higher ISO capabilities in modern cameras, a "low light" aperture is not that necessary. Let’s face it, at 6400 ISO or 25,200 ISO, even a f/4.0 lens can do the job of "low light" and make you able to take a photo at 1/125th of a second so there is no motion blur. But the advantage of the narrow depth of field that f/1.4 delivers serves to direct the viewer’s attention to what is in focus, as well as an artistic dreamy look of a blurred background and foreground.

Tokyo, Japan. Leica M-D 262 with Leica 50mm Summilux-M ASPH f/1.4 Black Chrome. © Thorsten Overgaard.

If we are honest, there's not many f/1.4 lenses that can produce this level of clarity, sharpness, details and color accuracy. If we are completely honest, in fact almost no lenses can do it. If we are pessimistic and realistic, there's maybe only this lens that offers these exact qualities.

"Bordering on the edge of perfection and artistry" is a good description. A true artist's brush.

Smokey bokeh

The word "bokeh" comes from Japanese and has come to mean "how aesthetically pleasing" the out-of-focus background looks.

Bokeh is defined as how the lens handles light; how unfocused light reflections plays in the lens. As such, it is fair to believe that a lens that handles clarity, details and colors well, will also have a beautiful bokeh.

Arthur Argote in New York. Leica M10 with Leica 50mm Summilux-M ASPH f/1.4. © Thorsten Overgaard.

Particularly in black and white, the 50mm Summilux-M ASPH f/1.4 stands out with an often silky smoke look. As if steam reproduced on silver paper. It's very unique as there aren’t other lenses in the stable of Leica lenses that have a similar look. In black and white, the bokeh has a texture of its own.

In color the bokeh has a sense of texture as well, as if silver gelatin particles, or actual light dust particles spread out in a fog.

It is not that every photo you take with the Leica 50mm Summilux-M ASPH f/1.4 has this look, but when you have some brightness in the background, it's as if the lens is able to capture the protons that else would hang around in the air unseen. It's a sort of magic trick this lens can perform.

Leica M10 with Leica 50mm Summilux-M ASPH f/1.4. © 2017-2018 Thorsten Overgaard.

Crisp with bokeh

Any f/1.4 lens has so narrow depth of field that elements in the foreground and background will be blurry out of focus. But the signature of the lens is what determines how this plays out.

How the lens paints with the light is what distinguish a lens like the Leica 50mm Summilux-M f/1.4 from any other lens.

Photographer Pep Williams in Los Angeles. Leica M10-P Safari with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

Best described, and what you may appreciate the most in practical use, is the lens' ability to define what matters (what is in focus) with extreme clarity and realism, while laying the background detail in a smoke screen that has a lot of built-in aesthetics.

Director Daniel Sackheim in Japan. Leica M-D 262 with Leica 50mm Summilux-M ASPH f/1.4 Black Chrome. © Thorsten Overgaard.

Perfection of clarity

Clarity is another word for sharpness, and one which I prefer. I want an image to stand out so clearly that it feels like I can touch the subject and sense its texture.

Normally sharpness - as expressed in photography - is just edges well-defined, which doesn't mean that you can sense the texture or even see details. Clarity has details, colors, textures - in which you can include the light. How the light reflects, bends, travels through surfaces.

(See my article , "What is Sharpness in Photography?" for more on sharpness).

Leica M10 with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten von Overgaard.

Leica 50mm Xenon f/1.5 (1936)
Leica 50mm Summarit f/1.5 (1949)
Leica 50mm Summilux-M f/1.4 I (1959-1960 non-ASPH)
Leica 50mm Summilux-M f/1.4 II (1962, non-ASPH)
Leica 50mm Summilux-M f/1.4 III (1992, non-ASPH)Leica 50mm Summilux-M ASPH f/1.4 (2004)
Leica 50mm Summilux-M ASPH f/1.4 LHSA Limited Edition 11627 Black (2005)
Leica 50mm Summilux-M ASPH f/1.4 LHSA Limited Edition 11628 Chrome (2005)
Leica 50mm Summilux-M ASPH f/1.4 Lenny Kravitz Edition (2015)
Leica 50mm Summilux-M ASPH f/1.4 Black Chrome Edition (2016)

The Leica 50mm Summilux-M ASPH f/1.4 Version II (1962) with ventilated hood (order no 12586)

Artist Mia Bego. Leica M10-P Safari with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

"Summilux" refers to the maximum lens aperture - in this case the f/1.4 lenses from Leica. "-lux" means light, and "Summi-" probably comes from Latin summum, meaning "highest." Lens of "Highest Light".

	Professor Dr. Max Berek
	Originally, the idea was to call the camera Leca, but another company already used that brand (building blocks), so the camera was named Leica.

The first Summilux lens introduced was the 1960-model of the 50mm Summilux f/1.4, which was a screw-mount lens. As you may know, any older screw-mount lens can be used on a modern Leica M with an adapter. If you do so, it's often the easiest to leave the adapter on that lens so it is already ready to fit on the camera.

Before the Summilux lenses started entering the arena, the most lightstrong lenses were the 1936-1950 Leica 50mm Xenon f/1.5.

In 1966 Leica broke the light wall again with the even higher light lens, the first Noctilux f/1.2 "Light of the Night" or "King of the Night" lens

Previously, Leica had made the 85/1.5 Summarex in 1948. The name of that lens was simply it's designer, Dr. Max Berek, who named lenses after his two favorite dogs. One of his dox was Rex, so he named the lens Summarex.

Summarit referred to the maximum lens aperture of 1949, which was f/1.5, but has then been used in later lens names for f/2.4 and f/2.5 lenses.

Summar has been used as a base for many names of Leica lenses, though the origin of the name is unknown. Leica has invented other names that were inspired by glass suppliers (Krown became Cron), dogs and so on.

The name Leica itself is derived from Leitz Camera, but originally they wanted to call the Leica camera LECA (which was already used by another brand with a very similar logo, LECA who makes building blocks and others from expanded clay).

For the lens names with Summar, these started out as Summar (f2.0) for the 1933 lens 50mm f2.0 Summar, then the Summitar (f2.0 in 1939), then the Summarex (85mm f1.5 in 1948), then the Summaron (35mm f.2.8 in 1948), then the Summarit f1.5 in 1949 and used again for the 40mm f2.4 Summarit on the Leica Minilux in 1995, which may have inspired the use of the name again for the 35mm, 50mm, 75mm and 90mm Summarit f2.5 in 2007.
Then Summicron (f2.0 in 1953 for the collapsible 50mm) and finally the Summilux (50mm f1.4 in 1959).

However, before Leitz in Wetzlar started making cameras in 1925, they used the name Mikro-Summar for their 42mm f4,5 around 1910 for their Leitz microscopes.

For complete overview of Leica lenses, visit my "Leica Lens Compendium and Serial Numbers".

Havana. Leica M9 with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

Tokyo, Japan. Leica M-D 262 with Leica 50mm Summilux-M ASPH f/1.4 Black Chrome. © Thorsten Overgaard.

Miami. Leica M 240 with Leica 50mm Summilux-M ASPH f/1.4 Black Chrome. © Thorsten Overgaard.

Watch my video review of the Leica 50mm Summilux-M ASPH f/1.4 Black Chrome limited edition on my Magic of Light photography television channel:

Havana, Cuba. Leica M10-P with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

Miami. Leica M-D 262 with Leica 50mm Summilux-M ASPH f/1.4 Black Chrome. © Thorsten Overgaard.

	A cut-through of the Leica 50mm Summilux-M ASPH f/1.4 lens (C50) shows the patented floating element

A beautiful piece of design

The optometric design is the mechanical design of the lens which determines how it focuses, how the aperture clicks, the weight, stability and many other things such as which materials to use where and for what.

Andre de Winter is from Indonesia, and his first design for Leica was when he started working for Leitz Canada Midland in March 1969.

His first assignment was the 50mm Noctilux f/1.0 (C271) with Dr. Mandler who was the CEO and head lens designer.

Andre de Winter did the Leica 50mm Summilux-M ASPH f/1.4 design in Solms, Germany, but these days he works from home in Midland, Canada. Recently Andre de Winter designed the Leitz Cine Summilux-C lenses for which he won an Oscar for the optometric design.

Lens designer Andre de Winter in his office in Midland, Canada. © Thorsten Overgaard.

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Leica instructor at Leica Store Nuremberg, Michel Birnbacher with his 50mm Summilux-M ASPH f/1.4 Leica M10 with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

One of the most beautiful Leica lenses, inside and outside

The Leica 50 mm Summilux-M ASPH f/1.4 from Leica is an aspherical lens, and according to lens designer Peter Karbe it's even an APO lens. That means it's corrected greatly for the color light rays, red, green and blue.

If you look at APO-lenses generally, they have really bright and accurate colors. That is the case for the Leica 90mm APO-Summicron-M ASPH f/2.0 Leica 50mm APO-Summicron-M ASPH f/2.0, as well as the older and more traditional use of APO, the Leica APO tele lenses for the Leica R system.

Leica M Monochrom with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

APO is a way to optimize the precision of the light rays (red, green and blue) so they meet in the same spot, so as to define texture and details. It was used to begin with, in long tele lenses where this precision was considered important (and usually expensive).

Over time, lens designer Peter Karbe has introduced APO in 50mm lenses and now even in wide angle lenses for the Leica SL system. The first lens for which he introduced it, was the Leica 50mm Summilux-M ASPH f/1.4, though he found it not suitable to label a 50mm lens with APO at that time.

Havana, Cuba. Leica M10-P with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

Leica 50mm Summilux and soft filters

A sharp lens with soft diffusion filters can make intersting pictures. Read my article here for more on that:

"Soft Images" by Thorsten Overgaard.

The Workhorse: Colors and details

I find that I bring the 50mm Summilux-M ASPH when I need precision, a compact lens and a sexy look with depth of field and bokeh.

The Summilux has quite a bit of the dreamy look (bokeh) that the Noctilux has, but has extremely crisp details and a very accurate color sense.

It's something that's taken me a while to realize; but I actually often take the 50mm Summilux when it really counts and I want to be able to move around and be able to go both close distant, as well as do group shots or such.

It's a lens you can never fail with.

Panasonic Lumix DC S1R with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

Leica M10-P Safari with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

My favorite 50mm lenses

My favorite lens is – if you have looked at my website you know – I shoot a lot with the Leica 50mm Noctilux-M ASPH f/0.95 and I often shoot it wide open. That's really a lens I like a lot.

I have also used the Leica 50mm Summicron-M f/2.0 Version II from the 60’s a lot, the one that's also called “Rigid”. It's not an expensive lens. It's a really good lens, but there're so many of them so they're not really expensive; it's not a collector's item. They're usually from $500 and up. They only go up to $2000 if they're in perfect new condition.

But with the 50mm Summilux-m ASPH f/1.4 Black Chrome version, this lens has slowly moved in as one of the lenses I use the most.

Tokyo, Japan. Leica M-D 262 with Leica 50mm Summilux-M ASPH f/1.4 Black Chrome. © Thorsten Overgaard.

Anya in London. Leica M10-P with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

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One of the great things about the Leica 50mm Summilux-M ASPH f/1.4 is that it has closest focus distance at 70 cm, like in this photograph. © Thorsten Overgaard.

Bokeh. Leica M-D 262 with Leica 50mm Summilux-M ASPH f/1.4 Black Chrome. © Thorsten Overgaard.

Layla Bego in the Mustang GT 1966. Leica M10-P Safari with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

Panasonic Lumix DC S1R with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

My daughter Caroline. Leica M10-P Safari with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

Leica M10-P Safari with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

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Leica M10 with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

Leica 50mm Summilux-M ASPH f/1.4 LHSA Edition (2005)

In 2005, Leica made a limited run of the then newly designed 50mm Simmilux-M ASPH f/1.4 designed by Peter Karbe. This was the LHSA edition in black paint (glossy) and a silver chrome. The price upon release was around $3,000 and dropped a bit in the following years, then sky-rocketed towards $7,000 - $8,000 in 2015 and above $10,000 in 2020.

LHSA is Leica Historical Society of America, which is a collector’s association that everybody can be part of, from anywhere in the world.

Leica 50mm Summilux-M ASPH f/1.4 LHSA-edition is a beauty in black paint. Hood is part no 12586.

These limited edition lenses were sold separately, as well as with a special limited edition MP3.

The original 1959-version has yellow feet scale on the black lens, while the LHSA-edition (2005) and Limited Edition Black Chrome (2015) have red feet scale.

Leica focusing scale and colors used

On a silver lens, the Meters are black and the Feet are red. On a black lens, the Meters are white and the Feet are yellow. This is the traditional Leica colors used for feet and meters.
The focusing scale in meters and feet on the 50mm Summilux (1959-design).

Leica 50mm Summilux-M ASPH f/1.4
Lenny Kravitz "Reporter" Limited Edition of 125

In 2015 Leica Camera AG then released a very limited series of this lens in black paint, but intentionally brassed. A set of one black Leica M-P 240 camera and two lenses (35, 50) in a suitcase, designed and named after Lenny Kravitz.

The series of 125 numbered sets then sold out about 9-12 months after its release.

The limited edition 50mm Summilux in the Lenny Kravitz set is pre-brassed.

Lenny Kravitz "Reporter" limited edition of 125 sets in suitcase. Leica M-P 240 with Leica 35mm Summicron-M ASPH f/2.0 Black Paint and Leica 50mm Summilux-M ASPH f/1.4 Black Paint. All brassed and then given a clear lacquer as protection.

Layla Bego. Leica M10-P Safari with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

Leica 50mm Summilux-M ASPH f/1.4 BC (Black Chrome) 2016

Few months after the release of the Lenny Kravitz model, Leica released another series of 500 of the same lens, but in matt black (Black Chrome).

An up-to-date optically designed Leica 50mm Summilux-M ASPH f/1.4 lens, but in old-school 1959's brass design and barrels. Initially the retail price was $3,900 and then rose to $4,350 in autumn 2016 and $5,095 in 2020.

This is the one I got for myself.

Leica 50mm Summilux-M ASPH f/1.4 Black Chrome limited edition in 1959-design (500 released in 2015) on Leica M-D 262. Comes with hood (12586) and metal as well as plastic lens cap. © Thorsten Overgaard.

This is a little bit heavier to use because it's brass. The aperture ring is moving very softly and I like to shoot wide open so I don't want to have the aperture suddenly slide to something else. I thought that maybe I could put some tape on it so it stayed in place, but then I sent it in to Leica in Wetzlar and they actually adjusted it. After that adjustment the aperture ring is stiff and stays at f/1.4 as I want it to.

This is something that is always possible to do with Leica lenses. You can get the aperture ring and focusing ring adjusted to be looser or harder to turn.

Leica M10-P Safari with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

The ventilated shade that falls off

The lens shade is really heavy as it is also made of brass, and it's the clip-on type, made to be like the original ventilated lens shade for the 1959-model.

While the ventilated shade is a piece of beauty, it is also useless as it falls off whenever it gets a chance to do so. I had one of the first days when the shade fell off twice while walking through security in the airport. Off it went, and rolled across the floor. Thankfully I noticed, so I didn't lose it.

I made my own E43 ventilated shade with E46 filter thread

As I make ventilated lens shades for most Leica lenses, I had one made for this lens also, and you can buy it in Black Paint, Silver and RED from my website. This is a screw-on that stays on the lens and protects it from bumps and bangs, and flare as well, of course.

This is my daily ventilated shade that looks beautiful and more compact than the original, and which takes the bumps and beatings of everyday use. The original brass stays home in a box (with a dent from one of the times it flew off).

This one is aluminum, so it's lighter while it still looks the part!

The genius of my ventilated shade is that it has a E46 filter screw on the front so that you can add filters to the lens without taking off the ventilated shade, and without stacking filters that puts the shade further and further out (makes the lens longer).

The E43 ventilated shade I designed for my 50mm Summilux sits on the 43mm filter thread and has an E46 filter thread built-in in the front of the shade. The shade also fits the original 1959-designed 50mm Summilux lenses in black and silver (comes in Black Paint, Silver or RED).

The limited edition is 43mm filter

One thing you also find out when you get this vintage lens is that it's not a 46mm filter as with the traditional 50mm Summilux ASPH. It's got a 43mm filter, like the original 1959's design!

You can still get 43mm filters and they will fit. The only thing is that when you put on the filter you cannot put on that vintage brass lens shade the lens comes with (the design doesn't have space for it inside).

You can get very rare thin filters that fit if you are a collector and don't mind the premium price for getting a rare, original filter. Although, not all new 43mm filters that fit the lens, also fit the shade! There's no space for it sometimes.

Then Leica modified of the lens shade (2018)

Since 2018, Leica offers a free modification of the lens hood so it will screw in instead of clip-on. One has to send the shade to Leica in Wetzlar, and then they return it with the E43 screw mount fitted. They also return the spare part clip-on so it's possible to bring the shade back to the original look if one should want that (as it's meant as a collectors’ item).

A modified brass shade E43 for the 50mm Summilux Black Chrome.

Older limited editions

It might not be pretty, but it's different and rare. A Summilux with gold fittings, selling for about $4,000 in 2020.

Not pretty, but rare.

San Francisco. Leica M10-P with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

How to mount a filter
on the Leica 50mm Summilux-M ASPH f/1.4 Black Chrome
or any other 1959 non-ASPH version

You will notice that whereas the normal 50mm Summilux-M ASPH f/1.4 has a 46mm filter size, the limited editions has a filter size of 43mm. Not a big problem as 43mm ND filters and UV filters are also available. Just a surprise as no other current Leica lenses have a 43mm filter size (but all the 50/1.4 lenses did so in the old days).

But you will see that when the filter is mounted, the classic shade (part no 12586) doesn't fit onto the lens anymore! There exists a vintage UV filter that goes with the lens. I don't use UV-filter, so I haven't tried to get one.

But I do use ND (Neutral Density) filters, so I acquired a 43mm ND filter (3-stop or 0.9ND) and then fumbled with it for a bit.

Step 1		Step 2		Step 3
Put on the lens shade.		Drop the ND filter into the shade.		1) Lock filter first with the bayonet locks. 2) Then press it down with a finger and turn the whole shade with filter until it sits as tight as it can.

In actual fact, if you mount the shade first, and then drop the ND filter down into the bayonet locking mechanism (press the silver buttons to open the "reverse locks" for attaching the shade upside-down when traveling). Then you will see that it almost locks. If you then turn the shade around, the filter will actually screw onto the lens to some degree. Enough to make it stay there.

Obviously, when you want to take off the ND filter, you will have to turn the shade counter-clockwise until the filter screws let go of the screw on the lens.

Ken Rockwell has made this filter overview of 43mm filters for Leica lenses.

Leica M10-P Safari with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

Panasonic Lumix DC S1R with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

My own design, the "Always Wear A Camera" Mini Messenger Camera Bag. Leica M10-P Safari with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

Santana. Leica M10-P Safari with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

Writing notes in the park in Tokyo, Japan. Leica M-D 262 with Leica 50mm Summilux-M ASPH f/1.4 Black Chrome. © Thorsten Overgaard.

State Dining Room, The White House. Leica M10-P with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

Leica M10 with Leica 50mm Summilux-M ASPH f/1.4. © Thorsten Overgaard.

Leica M10-P Safari with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

Panasonic Lumix DC S1R with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

Actor Jason Dohring in Hollywood. Leica M 240 with Leica 50mm Summilux-M ASPH f/1.4 Black Chrome. © Thorsten Overgaard.

Miami Muscle Beach. Leica M 240 with Leica 50mm Summilux-M ASPH f/1.4 Black Chrome. © Thorsten Overgaard.

Leica M10 with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

Leica M10 Monochrom with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

Miami. Leica M 240 with Leica 50mm Summilux-M ASPH f/1.4 Black Chrome. © Thorsten Overgaard.

Leica M10-P with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

Paris Fashion Week. Leica M 240 with Leica 50mm Summilux-M ASPH f/1.4 Black Chrome. © Thorsten Overgaard.

Tokyo street portrait. Leica M 240 with Leica 50mm Summilux-M ASPH f/1.4 Black Chrome. © Thorsten Overgaard.

Moscow, Russia. Leica M 240 with Leica 50mm Summilux-M ASPH f/1.4 Black Chrome. © Thorsten Overgaard.

Beyonce and Jay-Z. Leica M10-P Safari with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

Miami Muscle Beach. Leica M 240 with Leica 50mm Summilux-M ASPH f/1.4 Black Chrome. © Thorsten Overgaard.

Leica M10-P Safari with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

New York. Leica M10 with Leica 50mm Summilux-M ASPH f/1.4. © Thorsten Overgaard.

Shadows and 50mm lenses

Newer Leica lensees, starting with the Leica 50mm Summilux-M ASPH f/1.4 seem to be able to see in the dark. Sahdow details are more crisp and the image seem to open up more. If you compare these next photos, you will easily spot the difference.

Proud owner of a Leica 50mm Summilux-M ASPH f/1.4, Hans van Dijk from Holland. Palermo, Italy. LLeica M9 with 50mm Summicron-M f/2.0 Version II (1956) © Thorsten Overgaard

Street portrait in Soho, London. Leica M10-P with Leica 50mm Summilux-M ASPH f/1.4 BC.(2004). © Thorsten Overgaard.

The Leica M9 and Leica 50mm Summilux-M ASPH f/1.4 in the hands of Birgit Krippner who used to shoot exclusively with this lens. Leica M9 with 50mm Summicron-M f/2.0 Version II (1956) © Thorsten Overgaard

Bob Goldins. Leica M10-P Safari with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

	Peter Karbe at the factory in Solms, with an original notebook of Max Berek from 1930. © Thorsten Overgaard

Peter Karbe, head of Leica optics design, worked on the 50mm Summilux-M ASPH f/1.4 for ten years, and in his spare time.

His masterpieces so far include the Leica 50mm APO-Summicron-M ASPH f/2.0 and the Leica 50mm Noctilux-M ASPH f/0.95. (See my article with interview with Peter Karbe on the Leica 50mm APO-Summicron-M ASPH f/2.0).

Here's an excerpt from a talk that David Farkas of Dale Photography had with Mr. Peter Karbe at Photokina in 2008:

Sitting with Peter you really get the feeling that these lenses are his children. Talk of certain lenses puts a small smile on his face and a glint in his eye. Then, he’ll go on about why it is special and unique. For instance, many know of his many years of work on the 50mm Summilux ASPH.

He is extremely proud of this lens, pointing to the MTF-chart and exclaiming that wide open at f/1.4 it resolves 40lp at above 50%.

He went into how he came up with the modified special double gauss design and how the back half of the lens is identical to the 35mm Summilux-M ASPH f/1.4, while the front half is identical to the Leica 50 Summicron. This was the secret to achieving such performance in a fast 50.

Then, he said that one Saturday morning over his first cup of coffee in his kitchen he thought about Dr. Walter Mandler. Apparently, after Mandler designed the Noctilux, he used the same design to build the 75 Summiux.

And while Peter doesn't like the 75 Lux, he decided that he needed to design a 75 based on the 50 ASPH design.

Shortly thereafter, keeping everything the same, except for removing one lens element in the first doublet behind the central ASPH element used to correct for aberrations caused at 1.4, he minted the design for the Leica 75 APO-Summicron-M ASPH f/2.0.

San Francisco. Leica M10-P Safari with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

Why the Leica 50mm Summilux is an APO lens

I asked if the design was the same why the 75 was an APO lens and the 50 wasn’t. Here is a bit of a shocker… the 50 lux ASPH is an APO lens, containing an APO-correction element. But, he thought the idea of an APO 50 was a bit silly so they never put it on the lens or in any marketing materials.

He really believes in revisiting the past for inspirations on the future. Peter said that he often thinks about what his predecessors from decades ago would do with today’s technology.

This was his inspiration with the Summarits. Classic designs with a modern twist. He studies and claims (who would doubt him) that he is familiar with the designs of almost all of the Leica lenses made to date. He has his favorites as well as examples that were not so successful.

Dave Chen. Leica M10 with Leica 50mm Summilux-M ASPH f/1.4. © 2018 Thorsten Overgaard.

According to Peter, the great leaps in lens design were brought about by technological advances. The first was with new types of glass, then with coatings, followed by computer modeling, and now just recently, advances in mechanical design and manufacturing.

This is why the S lenses and the new 21 Lux are as lightweight as they are. A lot of attention is now being paid by the design team to the manufacturing process. Karbe has organized small design teams in his fast-growing department to be more efficient and productive. An optics designer is paired with a mechanical designer and a production manager to develop the entire product, not just the optical path. Handling, feel, ease of manufacture, and consistency in quality control are equally important to imaging performance.

Rome, Italy. Leica TL2 with Leica 50mm Summilux-M ASPH f/1.4. © Thorsten Overgaard.

Also, by using more shared designs and more common components, more lenses can be brought to market faster. The 35 and 50 Summarit. The 75 and the 90 Summarit. The new 21 Lux and 24 Lux are all examples of this. With the 21 and the 24, one designer did both lenses simultaneously as they are fundamentally the same optical formula.

Another interesting thing I learned was that Leica started using computer-aided modeling back in the 1960’s before anyone else. Since that time, they have had their own proprietary software (kept up to date, of course) based on calculations made at Leica over the last 100 years. He says this is one of Leica’s real advantages that no one can copy.

Thorsten von Overgaard by Oliver von Overgaard. Leica M10-P Safari with Leica 50mm Summilux-M ASPH f/1.4 BC. © Oliver Overgaard.

Geert Remmery in Brussels. Leica M10 with Leica 50mm Summilux-M ASPH f/1.4. © Thorsten Overgaard.

LL Cool J. Leica M10-P Safari with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

The foundation of knowledge and expertise is handed down from each generation of lens designers to the next. The Leitz Glass Works has also been invaluable in learning about new formulations and the handling of exotic glass elements. These latest exotic glasses require a great deal of care in handling. Much like a piece of raw steel, this glass reacts adversely and rapidly with gasses in the air. They use a wet to wet to wet process in Solms, whereby the glass moves through the grinding, polishing and coating steps in one go, not spaced or binned. This is crucial to maintain the performance of these expensive elements which can cost more per ounce than pure silver.

We talked more about how the type of glass for certain lens elements are chosen and how, based on his experience, he just knows what effect this will have on aberrations. We discussed the trade-offs lens designers have to make and how MTF only tells part of the story."

Leica M10-P Safari with Leica 50mm Summilux-M ASPH f/1.4 BC. © Thorsten Overgaard.

Product photo of my "Always Wear A Camera" The Von 24hr Jetsetter Bag. Leica M10 with Leica 50mm Summilux-M ASPH f/1.4. © Thorsten Overgaard.

	1:2/50 the description says. But what does it mean?

1:

Basically means 1 divided with. But why is it on the front of the lens? If you look close, a lens will often say 1:2/50mm on the front, meaning it is a 50mm lens with an f/2.0 apterture. The 1: itself is a ratio, that indicates that the aperture diameter (25mm) is the ratio of 50mm divided with 2.
It's a strange way of writing product information on modern products, but here's how it's right:
a) A lens is called a 50mm lens because there is 50mm from the sensor to the center of focus inside the lens.
b) A lens is f/2.0 when the widest opening is 50mm divided with 2 = The lens opening is 25mm in diameter at it's widest. Had it been an f/2.8 lens (1:2.8/50), the widest aperture opening would be 50mm divided with 2.8 = 17.8mm.

35mm

a) 35mm lens is a lens that has a viewing angle of view is 63°vertically, 54° horizontally and 38° vertically within a 35mm film frame:
b) 35mm film format is a standard film format where the actual widt of the film is 35mm. In photography the frame within the widt of the film is 24mm (on the width) and 36mm (on the lenght of the film roll). 35mm was first used in 1892 by William Dickson and Thomas Edison for moving pictures with frames of 24 x 18mm, using film stock supplied by George Eastman (Kodak), and became the international standard for motion picture negative film in 1909 [later other formats came about such as Academy Ratio (22 x 16 mm), Widescreen (21.95 x 18.6 mm), Super 35 (24.89 x 18.66 mm) and Techiscope (22 x 9.47 mm)].
Oskar Barnack built his prototype Ur-Leica in 1913 as a device to test film stock and/or motion picture lenses and had it patented, but Ernst Leitz did not decide to produce it before 1924.
c) 35mm is often given as a comparison when talking about lenses in small cameras or cameras with other sensor/film format than the 24 x 36mm frame. The camera has a smaller sensor and hence uses a wider lens to capture the same image as a "35mm camera" would. Example: A camera with a 12 x 18 mm sensor has a 14mm lens on it, and even the lens is actually a 14mm, it is specified as a 28mm lens (35mm) which means that the resulting image is equivalent to a 28mm lens on a 35mm camera.

	The Leica 50mm APO-Summicron-M ASPH f/2.0 lens

50mm

a) 50mm lens is a lens that has a viewing angle of view is 47° vertically, 40° horizontally and 27° vertically within a 35mm film frame.
b) 50mm lens is often compared to the human eye. Not because of viewing angle but because of size ratio. The 50mm lens is the lens that comes closest to the size that the human eye see things (whereas the human eye has a much wider angle of view [120-200°] than the 50mm lens [47°], thought a more narrow focus (your eyes may observe very wide but your focus is on a limited view within that angle of view).

AF = Auto Focus. The idea is that the camera does the focusing itself (the word auto comes from Greek "self").

APO corrected basically means that the red, green and blue has been corrected to meet more precisely in the same spot. Clarity of colors and definition of details would be the result.

APO = in lens terminology stands for "apochromatically corrected". In most lenses, optical design concentrates the focus of blue light and green light into a single plane, but red light falls slightly into another plane of focus. In APO lenses, the design and expense has been put in to making red light focus on the same plane as blue and green. Under a microscope you would see that all light subject is now in focus, creating a sharper image overall. Many manufacturers offer APO designs, but in most of these only the very center of the lens is APO corrected. Leica prides itself on making most of the frame APO corrected.
APo-correction has traditionally been used for long tele lenses (and periscopes), but in recent years APO-correction has been applied to 50mm and wide angle lenses as well. One will notice that the colors are really bright and alive, almost more real than to the eye, in lenses like the Leica 90mm APO-Summicron-M ASPH f/2.0 and 50mm APO-Summicron-M ASPH f/2.0.
Apochromat; ORIGIN early 20th century, made of the two words; apo (Greek origin, away from) and chromatic (Latin origin, meaing relating to color).

Aperture = The f/ stop on the camera that regulates how much light passes through the lens by increasing or decreasing the hole through the lens. On a f/2.0 lens the lens is fully open" at f/2.0. At f/2.8 the aperture inside the lens make the hole through the lens smaller so only half the amount of light at f/2.0 passes through. For each f/-stop (4.0 - 5.6 - 8.0 - 11 - 16) you halve the light. The aperture of the lens is basically the focal length divided with the f/-stop = size of the hole (50mm divided with f/2.0 = the hole is 25 mm in diameter).
Besides regulating the amount of light (so as to match the correct exposure), the aperture also affects the dept of field: , which is how deep the sharpness is. To get the sough-after photos with narrow depth of field where the background is blurry, the lens has to be wide open at f/2.0 or so. Stopping the lens down to f/8 or f/16 will result on more depth of field, meaning the background will start becoming in focus. To maintain narrow depth of field, one can use the ISO sensitivity and/or the shutter speed to match the correct exposure (as aperture is only one of three ways to control the exposure; the correct amount of light).
ORIGIN: Late Middle English : from Latin apertura, from apert- ‘opened,’ from aperire ‘to open’.

The aperture blades inside the consist of a number of blades that - as the aperture ring on the lens is rotated - narrow into a smaller and smaller hole. © Thorsten Overgaard.

	spherical (ball)
	a-spherical (non-ball)

ASPH = (Aspherical lens) stands for "aspheric design". Most lenses have a spherical design - that is, the radius of curvature is constant. These are easy to manufacture by grinding while "spinning" the glass. This design however restricts the number of optical corrections that can be made to the design to render the most realistic image possible. ASPH lenses (a-spherical, meaning non-spherical), however, involve usually 1 element that does *not* have a constant radius of curvature. These elements can be made by 1) expensive manual grinding, 2) molded plastic, or 3) Leica's patented "press" process, where the element is pressed into an aspherical ("non-spherical") shape. This design allows Leica to introduce corrections into compact lens designs that weren't possible before. Practically, the lens performs "better" (up to interpretation) due to increased correction of the image, in a package not significantly bigger than the spherical version.

There is another Aspherical lens manufacture technique: an uneven coating layer is applied to a spherical lens. The coating is thicker on the edges (or on the center, depending). Canon "Lens Work II" calls these "simulated" aspherical lenses. Simulated and Glass-Molded (GMo) asphericals show up in non-L Canon lenses, while the L lenses have actual ground aspheric elements.

A- means non, or without. From Latin, ex.
Sphere: ORIGIN Middle English : from Old French espere, from late Latin sphera, earlier sphaera, from Greek sphaira "ball".

Normal spheric lens (grinded)		ASPH (note the shape of the glass as result of pressing rather than grinding)

	Bokeh of a Leica 50mm Noctilux-M ASPH f/0.95. British composer and producer Barrie Gledden. © 2013 Thorsten Overgaard.

	Bokeh of a Leica 50mm Noctilux-M ASPH f/0.95. British composer and producer Barrie Gledden. © 2013 Thorsten Overgaard.

Bokeh = The visual quality of the out-of-focus areas of a photographic image, especially as rendered by a particular lens: It's a matter of taste and usually photographers discuss a 'nice' or 'pleasant' bokeh (the out-of-focus area is always unsharp, which is why the quality discussed is if one likes the way it renders or not by a particular lens). The closer you get to something, the 'more' bokeh' you get (in that the focus becomes less for the background and foreground at close distances than at long distances). ORIGIN from Japanese 'bo-ke' which mean 'fuzzines' or 'blur.'.

Bokeh: The visual quality of the out-of-focus areas of a photographic image. Photo at Bar del Fico in Rome. Leica TL2 with Leica 35mm Summilux-TL ASPH f/1.4. © 2017 Thorsten Overgaard.

Camera - is today’s short name for Camera Obscura (meaning “a dark room”). Camera means Chambre and was used only as a Latin or alien word, actually only for Spanish soldiers’ rooms, until popularized in connection with photography in 1727: “Camera Obscura”. In 1793 the slang term “camera” was used by Sterne Tr. Shandy: “Will make drawings of you in the camera” and by Foster (1878), “The eye is a camera”. Camera Obscura was described by Iraqi scientist Ibn-al-Haytham in his book, “Book of Optics” (1021) and by Leonardo da Vinci in 1500; popularized and made widely known in 1589 by Baptista Porta when he mentioned the principle in his book “Natural Magic”. Johannes Kepler mentions Camera Obscura in 1604.
Camera = chambre (room), Obscura = dark (or cover).

Collapsible - Usually refers to a collapsible lens such as the Leica 50mm Elmarit-M f/2.8 Collapsible, or Leica 90mm Macro Elmar-M f4.0 Collapsible, etc. A collapsible lens is one that can collaps into a compact lens when not in use.

The Leica 50mm Elmar-M f/2.8 Collapsible on a Leica M10-P Safari. Here extruded for use; it can collapse into the camera so as to be more compact when not in use. © Thorsten Overgaard.

Contrast - The degree of difference between tones in a picture. Latin contra- ‘against’ + stare ‘stand.’

Normal to low contrast		High contrast

Depth - Distance between front and back. Distance from viewer and object.

	Lens distortion looks like this. The lines are not straight. Our eye uses distortion correction. Lens designers can design lenses so they have very little distortion, or they can make less complicated lens designs and "fix" the distortion in software.

	Lens distortion looks like this. The lines are not straight. Our eye uses distortion correction. Lens designers can design lenses so they have very little distortion, or they can make less complicated lens designs and "fix" the distortion in software.

Distortion = In photo optics/lenses: When straight lines in a scene don't remain straight because of optical aberration.

Lens designers can correct for distortion to a degree so the whole image field is perfect corrected and all lines remain straight. In modern lens design many designs rely on Software Distortion Correction (SDC).

The eye adjusts for distortion so we always see vertical and horizontal lines straight when we look at things. Even when you get new prescription glasses (if you use such), you will often experience distortion in your new glasses. After a few days they eyes have adjusted for the glasses and the distortion you saw to begin with is now gone. Software Distortion Correction (SDC) is far behind what the human eye can perform of adjustments. (Also see my definition on Perspective for more on the eye and optics)

Narrow Dept Of Field in use: The face is in focus, the hand in front is slightly out of focus, the background is much out of focus and blurry. Leica 50mm Noctilux f/1.0 at f/1.0 and 2.5 meters distance to subject in focus. © Thorsten Overgaard.

50mm f/1.4 lens at f/1.4.		50mm f/1.4 lens at f/5.6

	The lines on this 28mm lens indicates the DOF. Here the focus is on infinity, and if the lens is stopped down to f/1.6, objects from 1.8 meter to ininity will be 'acceptable sharp'.

DOF = Depth of Field (or Depth of Focus), an expression for how deep the focus is, or (more often use to express) how narrow the area of focus is. This is how much of the image, measured in depth or ditance, will be in focus or "acceptable sharp".

The appearance of the DOF is determined by:
1) aperture (the smaller the aperture hole is, the deeper is the depth of field, and opposite, the wider open a lens you se, the more narrow will the DOF be) and
2) distance to the subject (the farther away, the larger area is sharp; the closer the subject in focus is, the more narrow the DOF gets)..
The DOF scale measurement on top of the Leica lenses shows lines for each f-stop that indicates from which distance to which distance the image will be sharp. Shallow DOF is a generally used term in photography that refer to lenses with very narrow focus tolerance, like f/1.4 and f/0.95 lenses, which can be used to do selective focus; making irrelevant subjects in the foreground and background blurry so only the subjects of essence are in focus and catches the viewers eye).
in modern cameras like the Leica SL2, the camera has a DOF scale inside the viewfinder. As DOF is the same for all lens brands and designs, only depending on focal length, distance and aperture f-stop, the camera can calculate it and show a 'digital DOF scale" in the viewfinder.

Depth Of Field scale from Fujifilm, same lens with different aperture settings from f/2.0 to f/8.0.

Depth of Field: Focus is on the flowers and the photograph on the desk and the foreground and background is blurred as the depth of field is narrow. If one stop down the aperture of the lens from f/1.4 to f/5.6, more will be in focus. If one stop down the lens to f/16 even more (if not all) will be in forcus. Another rule: The closer you go to a subject (the less focusing range), the more narrow the Depth of Field will be. © 2017 Thorsten Overgaard.

Dynamic range. The grade of ‘contrast range’ (or number of tones) a film or sensor, or simply a photograph, possess between bright and dark tones. The human eye is said to have a dynamic range of 10-14 ‘stops’ (but because we scan area by area and compile a concept of the overall scene, they eye is often thought to have a much higher dynamic range), Film used to have 7-13 ‘stops’ and some modern sensors have up to 15-17 ‘stops’.E - Diameter in Leica filters and screw diameter, as in E46 which means that the filter diameter is 49mm for this lens. In general language, one would see Ø46 used, as Ø is the general symbol for diameter.

f/ (f-stop, also known as aperture).

f- (focal length). Often given in mm, for example 90mm. In the past they were often given in cm or inch, for example 9.5 cm or 3.2 inch.

f/1.25 is the size of the "hole through" the lens, the aperture. f/1.25 means focal length divided with 1.25. In the Leica 75mm NoctiluxM ASPH f/1.25, the "hole through" the lens at f/1.25 is 60mm in diameter. At f/1.4 the "the hole through" is 53.5mm in diameter. At f/4 the "hole through" is 18.75mm in diameter.
Each step smaller from f/1.4 to f/2.0 to f/2.8 to f/4.0 and son on is a reduction ofthe light to half for each step. The Noctilux f/1.25 therefore lets 50% more light in through the lens than a 75/1.4 Summilux.

f-stop = the ratio of the focal length (for example 50mm) of a camera lens to the diameter of the aperture being used for a particular shot. (E.g., f/8, indicating that the focal length is eight times the diameter of the aperture hole: 50mm/8 = 6,25 mm); or the other way around, the hole is the focal length divided with 8).
ORIGIN early 20th cent.: from f (denoting the focal length) and number.
One f-stop is a doubling or halving of the light going through the lens to the film, by adjusting the aperture riing. Adjusting the f-setting from f 1.4 to f.2.0 is halving the light that goes through the lens. Most Leica lenses has half f-stops to enable the photographer to adjust the light more precicely.

Flare = Burst of light. Internal reflections between (and within) lens elements inside a lens. Mostly, flare has a characteristic "space travel" look to it, making it cool. Particularly in older lenses with less or no coating of the glass surfaces to suppress this, it can be a really cool effect. In newer lens designs, the coatings and overall design try to suppress flare and any reflections to a degree, so that there is seldom any flare to be picked up (moving the lens to pick up a strong sunbeam), but instead a "milking out" (or "ghosting") of a circular area of the frame; meaning simply overexposed without any flare-looking flares.

Sunlight creating (fairly supressed) flare in the bottom right quadrant of the image of a modern lens.		The camera moved slightly to avoid the flare.
Older lenses with less coating, or without coating, are known to create flare that can look like this (Leica 50mm Summicron-M f/2.0 II Rigid model from the 1960's). © Thorsten Overgaard. Lens Flare in Star Trek (2013). JJ Abrams famously said, "I know there's too much lens flare ... I just love it so much. But I think admitting you're an addict is the first step towards recovery (ha ha)"

	A 28 mm lens has a 74° viewing angle

Focal length = Originally focal length referred to the distance from the sensor (or film in older days) to the center of focus inside the lens (28mm, 50mm, 400mm, etc). Today one call it effective focal length (EFL) as a 400mm lens is not nessesarily 400mm long due to optical constructions that can make it shorter. The 35-420mm zoom on the Leica V-Lux 1 is for example only ca. 135 mm long. Nobody uses that measurement, except those who construct lenses! For users of lenses, focal length refers to how wide the lens sees. The viewing angle, which is often given in for example 90° viewing angle for a 21mm lens, 74° viewing angle for a 28mm lens, 6° viewing angle for a 400mm lens, etc.
Each human eye individually has anywhere from a 120° to 200° angle of view, but focus only in the center.

Focus, in - Sharp and clear in appearance. Focus - “The burning point (of a lens or mirror)”. In Latin the word focus meant fireplace or hearth. The word was probably first employed outside of its Latin literal use as “the burning point of a lens or mirror” in optics, and then came to mean any central point. The German astronomer Johannes Kepler first recorded the word in this sense in 1604.

Frame lines = the lines inside a viwfinder that indicates the edger of the frame. In a Leica M, the viewfinder always is as wide view as 24-28mm. A mechanical contach on the lens (triggers the camreas frame selector) so the viewfinder shows the frame line of that lens. In the Leica M, the frame lines comes in sets, so there are alwaus twop sets of frame lines shown at any time (see illustration below).
(This is different than in most cameras where you only see what the lens captures: SLR cameras was the evolution in 1940's where the image from the lens was displayed directly onto a matte screen inside the camera via a mirror. Later mirrorless cameras, the viewfinder shows the exact picture that the sensor sees through the lens).

Frame lines of the Leica M, here showing the set of 35mm and 90mm framelines.

Ghosting = Secondary light or image from internal reflections between (and within) lens elements inside a lens. The reflected light may not always be in focus, so overall it looks like a "milked out" image. A subject in focus has brightened patches in front of it that come from reflections inside the lens. the most elementary look of ghosting is when you look in a rear-view mirror in a car at night and you see doubles of the headlights behind you (a strong one and a weaker one), because the headlights are reflected in a layer of clear glass on top of the mirror glass.

Degrees of ghosting from strong sunlight entering from outside the frame. To the right the outside light has been shielded with a shade.

Leica = A compound word derived from " (Lei)tz" and "(ca)mera". Apparently they were originally going to use "LECA", but another camera company already used a similar name in France, so they inserted the 'i' to prevent any confusion.

The word lens derives from lentil, because of the similar shape.

Lens - A piece of glass or similarly transparent material (like water or plastic). It has a shape so that it can direct light rays. The word “Lens” is used both for single piece of glass as well as a camera lens with several lenses that works together. The word lens if often used to refer to the entire camea lens, which is usually compose of seberal lens elements. From ‘lentil’ because similar in shape.

A camera lens consists of several shaped lens elements of glass. The lenses can also be made of simple cheap plastic as in "kit lenses" (sold with a camera as a kit to make a workable cheap package), but it is mostly very exotic glass (that can be heavy or light in weight, very hard or very soft in surface (esay to scratch or very resistant) with each optical glass recipe made to develop very specific qualities in how the glass and final lens treats light. As a general rule, high quality glass is soft, which is why some lenses has as their front and back element, a non-optical lens element that is there to protect the actual optical glass from scratches. As a side noite, Leica made their own glass laboraty, The Leitz Glass Laboratory, from 1949-1989, which deveopled 35 new glass types and took out more than 2,000 patents of glass recipes from more than 50,000 experimental melts of glass. These designs, or recipes, are still used today by the lens designers to obtain very specific optical results. Other lens manufacturers in the world of course have had their glass laboratories, and today one will find an interchange of glass patents amongst production facilities that service Leica, Nikon,, Fuji and so on with optical lens elements.

Lens hood = (also called a Lens shade or Ventilated Shade). A tube or ring attached to the front of a camera lens to prevent unwanted light from reaching the lens and sensor. In the past where lenses were not coated to prevent internal reflections inside the lens, the lens hood was often essential. These days where lenses are coated, the shade serves just as much as decoration and protection (bumper) as well.
ORIGIN Old English hod; related to Dutch hoed, German Hut 'hat,' also to hat.

Lens hood or Lens shade or ventilated shade. In the picture is a ventilated shade with clip-on mount to a 50mm f/2.0 lens. Ventilated means it has openings that allow for view from the viewfinder.

Lens names of Leica distinguish which widest aperture the lens has:

Light = Tiny particles called photons that behaves like both waves and particles. Light makes objects visible by reflecting off of them, and in photography that reflecting off of subjects is what creates textures, shapes, colors and luminance. Light in its natural form (emanating from the sun) also gives life to plants and living things, and makes (most) people happier. So far, nobody has been able to determine exactly what light is. The word photography means “writing with light” (photo = light, -graphy = writing). Read more about light in my book Finding the Magic of Light.

LMT - Leica Thread-Mount: Also known as M39, is the screw mounted lenses for Leica cameras. It’s a simple as that; you screw on the lens, and back in 1932, the possibility to change the lens was the big news hwen introduced by Leica on the Leica III. The M39 system was updated with the M Bayonet from 1954 for the Leica M3. The M bayonet is a quick way to change lenses and is the current mount for Leica M digital rangefinders.

M (as in "M3", "M6", "M7" etc.)
A) The M originally stands for "Messsucher", which is German "Meßsucher" for "Rangefinder". The "3" in M3 was chosen because of the three bright line finders for the 50, 90 and 135 mm lenses. Later the numbers of the M cameras were more or less chosen to follow each other.
M-body evolution in chronologic order:
M3 - MP - M2 - M1 - MD - MDA - M4 - M5 - CL - MD-2 - M4-2 - M4-P - M6 - M6 TTL - M7 - MP - M8 - M8.2 - M9 - M9-P - MM (black and white sensor) - ME (Type 220) - Leica M (Type 240) - Leica M-P 240 - Leica M 246 Monochrom - Leica M-A (type 127, film camera) - Leica M 262 - Leica M-D 262 (without a screen) - Leica M10 - Leica M10-P.
B) M also refer to M-mount as the M bayonet that couple the Leica M lenses to the Leica M camera. Before the M bayonet the coupling between the camera and lens was screwmount.
C) M nowadays refer to the Leica M line of cameras rather than the "Messsucher".

The Leica M bayonet on the Leica M10.

M-mount: The Leica M-mount is a bayonet that was introduced with the Leica M3 camera in 1954 and has been used on all subsequent Leica M cameras, as well as on the Epson R-D1, Konica Hexar RF, Minolta CLE, Ricoh GXR, Rollei 35RF, Voigtländer Bessa, and Zeiss Ikon cameras (2019).
Compared to the previous screw mount (M39), the M mount requires a quick turn of the lens, and ithe lens is mounted. The patent for the M-bayonet ("Bajonettvorrichtung für die lösbare Verbindung zweier Kamerateile") was registered by Ernst Leitz GmbH 10 February 1950 (patent number DE853384). Hugo Wehrenfennig was credited with the invention.

M9
Leica M9 is a model name for the Leica M9 that was introduced on September 9, 2009 (as the first full-frame digital Leica M). It was the latest model designation using the M and a number. From their next model, Leica Camera AG introduced a new model system so each camera would simply be a Leica M but then with a model designation like Typ 240, Typ 246, Typ M-D 262 and so on. The idea was inspired from Apple who name their computers for example MacBook Pro and then it has a sub- model number designation which model it is (and which would define speed of processor, etc).

Leica M9 digital rangefinder (2009). © Thorsten Overgaard.

Mandler, Dr. Walter (1922 - 2005)
Legendary Leica lens designer and CEO of Ernst Leitz Canada (ELCAN) 1952-1985. Read more in Leica History.

Dr. Walter Mandler (center) at the Ernst Leitz Camera factory.

Megapixel (or MP) - Millions of pixels. See pixel further down. How many units of RGB is recorded by a given sensor by taking height x widt. A Leica M10 delivers a 5952 x 3968 pixel file = 23,617,536 piexls. On a screen the resolution you choose determines the size of the image. Say you have a 5000 pixel wide file and your screen is set for 8000 pixels wide. Then the image will fill only the 5000 pixels fo the 8000 and the rest will be empty, If you then change the screen resolution to 5000 wide, the image would be able to fill out the whole screen.

Meßsucher = (rangefinder or distance finder) = Mess = range, sucher = finder. It is always correctly written with the "ß". There are technically not three "s", rather the "ß" and one "s" because it is a word constructed by the combining of two precise words.

Focal length is determined by the distance from focus inside the lens to sensor surface to, and is given in milliemeters (mm). © Thorsten Overgaard.

mm = millimeter(s), as in a 50mm lens. (Earlier in lens history lenses focal length was given in cm = centimeters; as in a 5 cm lens). For anyone used to centimeters and millimeters, it’s no wonder. But if you grew up with inches, feet and yards, you may have had a hard time grasping what a 50mm lens was. But as lenses were designed first in Europe, the metric system with centimeters and millimeters was used to describe lenses.
(Leica and others made lenses for a while with either meter scale or feet scale; but then eventually started including meter and feet on all the lenses (two scales, usually distinguished with different colors). However, the lens' focal length remained always 50mm, 75mm and so on).
The reason a 50mm lens is a 50mm lens is that there is 50mm from the focus plane (the film or sensor surface) to the center of focus inside the lens. When photography was a young subject, it was engineers who made it all, and the users were expected to understand. The engineers were so into the making of the lenses, that it apparently never dawned upon them that today’s users would think of a 21mm lens as a wide angle lens rather than a lens where there is 21mm from the sensor to the center of focus inside the optics.

ND
Neutral Density filters are grey filters function as 'sunglasses' for lenses. They simply block the light so that a lens can work at for example f/0.95 or f/2.0 in sunshine.
If a camera is set to 200 ISO and the maximum shutter speed is 1/4.000, this will usually result that the lens has to be at f/2.8 or smaller aperture in sunshine. Else the image will over-exposed. So in order til stay within the maximum shutter speed of 1/4.000 and still use a lightstrong lens wide open, one mount a ND-filter that reduce the light with 3 stops (8X) or 6 stops (64x).
For video ND-filters are used quite a lot (as the shutter speed for video is 1/60), and ND-filters are also used to reduce the light for really long multi-exposures at night (stop-motion video and stills).
ND-filters also exist as variable ND-filters so one can adjust the amount of light going through from for example 1 stop (2X) to 6 stops (64X).
ND-filters also exist as graduated ND-filters where the top of the filter is dark and then gradually tone over in no filter (so as to reduce the skylight in a landscape for example).
The ND filters are called Neutral because it is a neutral filter. It doesn't change colors, only the amount of light.

ND-filters / gray-filters.

Noctilux = Also known as "King of the Night" because "Nocti" means Night and "Lux" means Light. The f/1.0 lenes from Leica are named "Noctilux". The first Leica Noctilux lens was the 50mm Noctilux f/1.2 which shortly after it's introduction was improved to the 50mm Noctilux f/1.0. In the current model the f-stop has been improved further to f/0.95.
"Noctilux" refers to the maximum lens aperture - here f1.0 . "Nocti" for nocturnal (occurring or happening at night; ORIGIN late 15th cent.: from late Latin nocturnalis, from Latin nocturnus ‘of the night,’ from nox, noct- ‘night.), "lux" for light. The Leica Noctilux 50mm f1.0 is famous for enabling the photographer to take photos even there is only candleligts to lit the scene. See the article "Noctilux - King of the Night"

The Noctilux "King of the Night" lens. From left the f/0.95 in silver (same on the camera, in black), the f/1.0 in the back and the rare and expensive first model, the f/1.2 in the front.

No.
Number, on this site Leica catalog numbers or order numbers. Some the numbers changed depending on the number of cams in the lens: The Elmarit-R f2.8/135mm started life as No. 11 111, however when fitted with 2 cams for the SL became No. 11 211, yet another No. for the 3 cams lens and a fourth number for 3 cam only at the end of its life. Number changes also applied to M lenses depending on whether they were screw-thread, bayonet or for M3 with “spectacles”. Thus the No. in the Thorsten Overgaard Leica Lens Compendium list is a guideline but not a comlete list of existing catalog numbers.

Optic = Eye or vision. From French optique or medieval Latin opticus, from Greek optikos, from optos ‘seen.’

Perspective = The way objects appear to the eye; their relative position and distance. Also, selective focus (foreground and background out of focus) can change the perception of perspective (also see Three-dimensional). A wide angle "widens" the perspective and makes objects further away appear smaller than they are to the eye; and objects closer, relatively larger than they are to the eye. A tele lens will "flatten" the perspective and often objects further away will appear relatively larger than close objects than they are in real life. A 50mm lens is the one closest to the perspective and enlargement ratio of the human eye.

The word Perspective comes from the latin word for optics (perspicere, per- ‘through’ + specere ‘to look’), and so-called Renaissance painting is simply painting done within the framework of optics and the linear perspective it presents.

Perspective is relative position and distance. The objects nearby are larger than objects far away. This is how the eye and the mind calculate distance. The eye and the camera automatically captures perspective. In darwing and painting one would see "stupid" two-dimensional drawings 500 years B.C where elements were thrown into the mix without considering that a an object far away must be smaller than if close to the viewer. The word "perspective" comes from "to look through (optics)". Pier 7 in San Francisco by Thorsten Overgaard. Leica M11 with Leica 50mm Noctilux-M ASPH f/0.95.

	Vanishing points are the points where lines meet. This is how you make perspective in paintings and drawings (and some times make movie sets or theatre stages appear more three-dimensional than they are)

Painters works with vanishing points, which is where the lines meet, so as to create an illusion of perspective and three-dimensional effect on a two-dimensional painting or drawing.

The human eye corrects for perspective to an extreme degree. We always see vertical lines vertical and horisontal lines horisontal: The eye has a angle of view equivalent to an 8mm wide angle lens, a size ratio equivalent to a 50mm lens and we focus on relatively small area of the viewing field - one at the time. Three things happens that are worth paying attention to:

1) We compile areas of our view that we focus on, to one conceptual image that "we see". Ansel Adams, the great American landscape photographer pointed out that a large camera used for landscape photography capture every detail in focus and sharp so you can view it in detail after; but the eye does not see everything in focus when you try to compose the landscape photography, the eye scans only one part at a time and stitch the idea together. This makes composing or prevision of a landscape photography challenging.

2) We compile areas of our view that we individually adjust the exposure of. A camera adjust the exposure of the whole image frame to one exposure. That's why what looks like a nice picture to the eye of houses in sunshine with a blue sky above, becomes a photograph of darker buildings with a bright white sky: The camera simply can't take one picture that compare to what we "compiled" with our eyes, adjusting for each type of light.

3) Objects (on a table, for example) in the bottom of our viewing field will appear 100% perspective corrected - to a degree that it is impossible to correct in optics, with or without software correction. A wide angle lens, even with little distortion, will exaggerate the proportions of the closet part so it - to the eye - looks wrong.

Perspective distortion: Comparing these two photographs you can see how the cup stretches in the 28mm wide angle photograph compared to the 50mm photograph. Both actually has a little stretch because both the cup is in the edge of the frame in both photographs. © Thorsten Overgaard.

Rigid - Refers usually to the Leica 50mm Summicron-M f/2.0 "Rigid" of 1956.
It is called "Rigid" because, unlike the 50mm Collapsible, this one is not able to be changed.
Rigid means stiff, uable to be forced out of shape. Not able to be changed. From Latin rigere, "be stiff".
The name is a little confusion nowadays as all or most lenses are rigid today, but back in 1925-1956, many lenses were collapsible so the camera was compact when not in use. Just like compact cameras today often has a lens that extrudes when the camera is turned on, and collaps into the camera body when the camera is turned off.

RF
(R)ange (F)inder - the mechano-optical mechanism which allows M Leicas to focus.
Alternative meaning - RF is also shorthand for Hexar RF , Konica's motorised "M-lens-compatible" rangefinder camera released in 2000.

Saturation: How colorful, intense or pure the color is. Less saturation would be less colorful, more saturation would be more colorful. In today’s photography, de-saturating a photo on the computer will gradually make it less and less colorful; and full de-saturation would make it into a black and white photo.

A photo from Verona, Italy de-saturated, normal saturated and over-saturated. © Thorsten Overgaard.

Sharpness - See “Focus”

Summarex
The great thing about being a lens designer is that you get to name the lens. Dr. Max Berek who worked for Leitz from 1912 till his death in 1949 named lenses after his two favorite dogs. One was Sumamrex named after his dog Rex, the other Hektor named after his dog Hektor.

Summarit
Refers to the maximum lens aperture - here f/1.5.

Summicron = Refers to the maximum lens aperture - here f/2.0 . There are many guesses how this name came about, a popular one being that the "summi" came from "summit" (summit means the highest point of a hill or mountain; the highest attainable level of achievement) while the "cron" came from "chroma" (ie. for colour). Not so: The name (Summi)cron was used because the lens used Crown glass for the first time, which Leitz bought from Chance Brothers in England. The first batch of lenses were named Summikron (Crown = Krone in Deutsch). The Summi(cron) is a development from the orignal Summar (the 50mm f2.0 lens anno 1933). Vario-Summicron, Vario-Elmarit is Leica Camera AG's name for zoom lenses, for example the Vario-Summicron f/2.0 as the one that is on the Leica Digilux 2.

Summilux = Refers to the maximum lens aperture - here f/1.4 , "-lux" added for "light" (ie. the enhanced light gathering abilities). In Leica terminology a Summilux is always a f/1.4 lens and a Summicron is a f/2.0 lens.

Three-dimensional = Having the three dimensions of height, width and depth. In photography and lens design, three-dimensional effect is also the perception of even small micro-details; the texture of skin can appear flat and dead or three-dimensional and alive. Also, selective focus (foreground and background out of focus) can change the perception of depth. Also see Perspective.

Three-dimensional = Having the three dimensions of height, width and depth. Melrose Avenue in Los Angeles. Leica TL2 with Leica 35mm Summilux-TL ASPH f/1.4. © 2017 Thorsten Overgaard.

Ventilated shade on a 35mm of Elliott Erwitt's Leica MP camera.

Ventilated Shade - A shade is a hood in front of a lens that provides shade from light going straight onto the lens from outside what you are photographing, which could cause internal reflections like flare, which would make the picture less contrasty.
The ventilated shade has holes so it doesn't obstructs the view from the viewfinder. In many of today’s mirrorless cameras where there is no viewfinder looking ver the lens, so there is no actual need for a ventilated shade; but they are considered classic or vintage looking and are still in high demand. It makes no difference for the purpose of the shade (to create shadow) if it is ventilated or not.

Ventilated Shade for the Leica Q. I make ventilated shades for most lenses and sell them from here.

Viewfinder a device on a camera showing the field of view of the lens. Also known as the German word "Messucher" (or Meßsucher).
1) A built-in viewfinder in a camera that simply show the frame you get when you look through the viewfinder.
2) A rangefinder viewfinder which is also used to focus the lens. In Leica M cameras two pictures has to meet and lay 'on top of each other' for the picture to be in focus.
3) An external viewfinder, usually on top of the camera in the flash shoe, so as to show the field of view of lenses vider than what the built-in viewfinder can show (15mm, 21mm, 24mm, 28mm etc viewfinders exist)
4) Very simple "aiming-devices" on top of a camera that is simply a metal frame without any optics. Just a frame, as for example very old cameras (the original Leica), or when using cameras in diving where you can't look through the camera.
5) A Electronic Viewfinder (EVF) that shows what the sensor sees "live".

Zone System -A system of 11 greytones. Ansel Adams worked out the Zone System in the 1940's with Fred Archer. It may look as simply a grey scale (and it is) but it's the use that has troubled many. If you use a normal external light meter, it will give you the exact amount of light and you can expose your photograph based on that and it will be correct. 

What Ansel Adams basically did was that he studied (by measuring with a spot meter), what the exact grey tones were of the sky, the clouds, the sand, the water, the skin and so on at different times of the day.
You could say that he built up a conceptual understanding of how different materials of different colors and reflective surface would look in black and white at different times of day (or different light conditions). He also realized that a tone changes for the human eye depending on it's size and in which context of other tones it is seen. 

In short, you could say that the Zone System is know how something would look in black and white when looking at a scenery. Some who have struggled with the Zone System have done so because they think it is a rule. It is not.

How Ansel Adams made New Mexico look:		How most people see New Mexico:
The artistic use of the Zone System.

Ansel Adams developed the Zone System to understand light for himself, but also as a fundament for teaching the light, exposure and making the final photograph. How will it look if you do the usual, and what will it look like if you manipulate it. But most interstingly; how do you work with light, cameras and photographic materials to achieve the look you envision. 

The Zone System is meant as a basis on which to create your own aesthetic style and communication.  Photography is painting with light. The greyscale is our palette. Ideally we should have a conceptual understanding of the tones and be able to use them intuitive. That was his vision for us all.

Thorsten Overgaard in New York, explaining the Zone System in his "Street Photography Masterclass".

Ø - Diameter. As in Ø49 for example which means that the filter diameter is 49mm for this lens (or if a filter is Ø49, it is 49mm in diameter and fits that Ø49 lens). Leica uses E to express their filters sizes, as in E49 for a 49mm filter size.

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For help, corrections and information to
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Andre de Winter
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– Thorsten Overgaard
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