ReviewPosted March, 2015

Leica Summicron-C 40/2




The Leica Summicron-C 40/2 is a discontinued normal lens for the Leica M-mount. Produced for the Leica CL – the “Compact Leica” during 1973–76, there are no versions to keep track of. There is a Minolta descendant – the M-Rokkor 40/2 – with improved coatings but otherwise identical optics. It seems closely related to the Summicron 35/2 III, sharing the same number of elements and basic optical design, as well as many imaging characteristics.

It’s a tiny lens, the smallest Leica’s ever produced. The size, fairly fast aperture and very reasonable price on the used market makes it an interesting option.


40mm is a slightly uncommon focal length, but is actually closer to a perfect normal than the traditional 50mm. Being an f/2 lens means that the lens has a 20mm physical aperture. As all M-mount lenses, it’s manual focus only. It’s a classical double-gauss design. All elements are spherical, but the front element is made of glass with a high refractive index. Elements are single coated. The odd thread size makes this lens tricky to use with filters.

Lens-mount Leica M bayonet
Length 23.5 mm
Weight 127g
Diaphragm 10 blades, f/2-f/16, half stops
Elements / groups 6 / 4
MFD 0.8m
Filter thread Series 5.5

Appearance & construction

While built to a price, the Summicron-C doesn’t feel any less well constructed than other Leica lenses from the same time. Build quality is fantastic. The outer housing is completely made from anodised aluminium, very durable but shows scuffing with use. The small focusing handle is the only visible part that’s plastic.

Markings are engraved in DIN and painted white. The imperial scale is painted yellow, retaining good visibility in lower light. The mounting indicator is missing on my copy but looks like plastic.

The internals seem good as well. The focussing helicoid is brass. There’s a beautifully constructed 10 bladed diaphragm, most modern Leica lenses make due with 8.

My copy needs a service, probably the first in its life, the moving parts beginning to become stiff. With proper care I think this will hold up just as well as other Leica lenses, and better than most of the Voigtländer or Zeiss ZM lenses.

The all metal construction makes it feel dense and heavy for its size, but it remains the lightest lens that Leica have produced. It really is tiny too, the just over 2cm long barrel makes it one of the smallest lenses made for the M-mount.

The hood and lens cap are the only parts feeling less nicely made. The collapsible hood is made of rubber and screws in to the filter thread. Attached it extends the lens by just over half a centimetre, folding out to around 2cm with a small tug. It’s actually a rather practical solution. However rubber is not as nice a material when it reaches a certain age. Both practically and aesthetically. There are some ergonomic issues described below. The lens cap fits into the collapsed hood with a friction fit. Unfortunately this means the cap can’t be used without the hood.




Ergonomics are mostly great, if slightly odd. Despite the small size controls are easy to find and manipulate. The focusing handle works well but is not as comfortable or quick to work with as a traditional tab.

The aperture adjusts with a ring that has a gap of around 120°, making it easier to find and adjust than the lever of the Summicron 35 III or the “ears” of e.g. the Voigtländer 40/1.4. The disadvantage is that it’s harder to tell the current aperture by feel.

As mentioned, my copy needs a tune up – the focusing is stiff and the aperture stops feel slightly indistinct. Pretty much as expected of a 40 year old lens that’s never been serviced. Servicing will probably bring it back to smooth and distinct.

There are some minor issues using the lens with the included hood. When collapsed the hood is very close to the aperture ring and is quite a bit wider, interfering with its use. The issue is exasperated by the stickiness of the rubber. Extending the hood eliminates the problem, but the 40 year old material isn’t as flexible as it probably used to be. Folding the hood out takes a slight bit of fiddling, something you don’t always have time with. As a consequence I tend to leave the hood extended or more often – remove it altogether, opting for an aftermarket cap instead.


Image quality

While the Summicron-C doesn’t quite perform on the level of more modern benchmark lenses, the overall image quality and rendering is very pleasant. It’s impressive for its size and specifications and compares well to similar options.

Rendition characteristics similar to contemporary Leica lenses are also clear. The smooth sharpness, good colour separation and pleasant overall character can be recognised from for instance the Summicron 50, but is not at quite the same level of sophistication.

Simple coatings means more issues with loss of contrast and flare. The compact, symmetrical design can be an issue on digital bodies, depending on sensor filter stack (see In Use section).

Resolution & contrast

Resolution is high already wide open. Definition drops slightly towards the edges and is poor in the deep corners. Micro contrast is moderate wide open but improves stopping down. Spherical aberration lowers mid level contrast wide open and gives a gentle glow, especially towards the corners. Global contrast is well balanced with good retention of detail in the mid tones.

Stopping down rapidly improves resolution and contrast uniformly across the frame, f/4 resulting in very good performance in all but the deep corners and f/8 being quite impressive with very even performance across the frame. Not all compact, high speed lenses improve to this level stopping down.

Characteristics are retained at both near and far distances.


Colors are delicate and natural with impressive separation between tones. A very pleasant palette overall.

Bokeh & transitions

While 40/2 does not result in razor thin depth of field, there’s plenty of separation. Bokeh is poor, especially in challenging conditions – wide open it shows high contrast and sharp edged highlights. Stopping down improves smoothness — f/2.8 gives good balance between separation, resolution and bokeh.


There’s almost no distortion – a very slight barrel shaped curvature can be measured but is rarely visible.

The lens is single coated, making it prone to flare issues. In challenging light conditions such as inclined light or high contrast scenes almost every deviation imaginable can be seen in to some extent. Veiling and resulting loss of contrast is common when the sun is in the outer perimeter or just outside the frame, when light hits the front element at an angle. Glare is mostly visible in vicinity to strong light but the opposite side of the frame is sometimes also affected. Ghosting can be seen as well as major streaking. Most of these issues can be reduced slightly by using the hood, but not circumvented completely. I wouldn’t necessarily call it a poor performer since most aberrations are moderate in severity. Due to the diversity and variety of the problems, it’s slightly tricky to learn every pitfall and how to avoid them. Compared to other Leica lenses of the same age, performance is similar. Newer lenses are better. Compared to other older lenses by most manufacturers, the performance is better.

Vignetting is visible but fairly low, as is chromatic aberration. There’s pronounced coma making the lens poor for nightscapes. Sunstars have 10 points stopped down. There’s no focus shift.

Overall rendering

The Summicron-C has a very pleasant signature. The sharp but not clinical wide open characteristics, fantastic performance stopped down and pleasant colour palette results in very covetable output. The susceptibility to flare can be a problem depending on subject and preferences – I generally find that flare can add a bit of character to images, however the diversity of the issues with this lens can make it trickier to use.

Bokeh sample at f/2. Quite messy.


1:1 crop, f/2.8. Note very good definition of detail, as well as improved bokeh.


Many different types of flare can be seen shooting this lens. The worst problems occur when the sun is just outside the frame like in this example. When the sun is actually in the frame the performance is surprisingly fair (see e.g. first and last images on this page).

Specifics in use

I’ve had this lens for several years by now, and have shot it quite a bit on several cameras. Here are some observations from using it.

While an uncommon focal length, 40mm is one of my favourites. To me it feels natural and easy to shoot – balanced perspective, some separation, not feeling overly long or wide. Because of this I’ve been through my fair share of 40mm lenses – the Konica 40/1.8, Panasonic 20/1.7, Voigtländer 40/2 & Voigtländer 40/1.4 have all passed through my hands. In my book the Summicron-C shares the top spot with only the Voigtländer 40/1.4.

An issue with shooting M-mount 40mm lenses is that only the Leica CL and Voigtländer Bessa R3M/A have corresponding framelines. On most M-mount cameras 50mm framelines are brought up instead. While framelines are always an approximation, 35mm would be a closer match. This can be worked around by showing a different set of framelines with the frameline preview lever on most Leicas. Another alternative is to file down the frameline index pin on the rear mount, making the camera recognize the lens as a 35 instead. I’ve left the pin untouched on my lens, instead framing liberally using the 50mm framelines and manually bringing up the 35mm ones at times when I’ve wanted higher accuracy. While fiddly in theory, it generally works well.

The focusing cam of the Summicron-C and Elmarit-C are slightly different than normal M-mount lenses with a sloped profile instead of a perpendicular one. According to Leica this could affect focus accuracy on M cameras. Many speculate that this statement was made to push people towards getting the more expensive lenses instead of the C-variations. I’ve also seen reports that Leica changed the spec on the focus roller on the M6 and newer cameras, ensuring that the roller is always centred and resulting in accurate focus despite the sloped cam. I've not had any accuracy issues on the Leica M9 in any case.

On live view based cameras these issues are of course irrelevant, instead resulting instead in an easy to shoot, small piece of kit. Unfortunately performance suffers slightly due to the compact design and associated ray angle issues.

I bought the lens as a complete package with the Leica CL, the Summicron-C 40, and the Elmar-C 90 at a bargain price. I’ve shot the CL quite a bit with the 40, a very pleasant combination to use despite my preference towards digital.

Leica CL

Fantastic. Good performance wide open, great stopped down. Issues seem slightly less pronounced than on digital. The viewfinder works well with the 40mm lens despite being slightly smaller than on other M-mount cameras, and has correct framelines. It’s clear that the camera and lens were made for each other – they balance very well together. A very compact, capable and pleasant combination to use.

Leica M9

Fantastic. Good performance wide open, great stopped down. Very pleasant colours and overall signature. No blockage of the viewfinder. The lens brings up 50mm framelines which leads to less accurate framing than 35mm frames that can be brought up using preview lever. Selecting the Summicron 35 IV in the correction menu gives good results without colour shifts or vignetting. Almost disappears on the M9, being so small and light. Very pleasant ergonomically. Relatively large aperture and short focal length makes the combination useable in all but the lowest of light.

Sony NEX–7

Average. Balances very well and is ergonomically fantastic on the tiny NEX–7. The resulting 60mm is a surprisingly nice focal lenght to shoot. Struggles slightly at f/2 to render fine detail on the high resolution sensor, f/2.8 gives better performance. Definition drops faster than on Leica bodies towards the edges, especially wide open and close to infinity which gives poor results. Stopping down improves resolution with f/8 giving impressive performance across the frame. Fewer issues at closer distances. Very nice colour output. No significant colour shift.

Sony A7

Poor. Issues at wider apertures due to ray angles. Balances well and is ergonomically great on the A7. Resolution drops far faster than on Leica bodies towards the edges wide open. F/2 is borderline usable. Significant field curvature away from the camera can be seen at closer distances as well as haziness across the frame. Stopping down improves performance. F2.8 and 4 overall performance is fair and useable in most situations, but issues can still be seen in edges and corners. F/8 is needed for good resolution across the frame and f/11 for the deep corners. Pleasant colour output. No significant colour shift.

Alternatives to consider

While uncommon there’s one more excellent 40mm lens in the M-mount. Depending on ones preferences a 35mm or 50mm lens can also be a good alternative. To me 35mm feels close, 50 not so much. These are the most relevant options in my opinion.

Leica Summicron 35/2

This, the slightly wider sibling to the Summicron-C is available in a number of different versions. All of them far more expensive. I’ve yet to shot with any of them. The Summicron-C 40 is optically most similar to the third version. Performance will be comparable regardless of version. The later ASPH version gives higher resolution wide open and in the corners and has less issues with flare, but is far larger and heavier. Ergonomics generally look slightly better on all versions of the 35/2.

Leica Summicron 50/2

While I personally believe that 40mm feels more similar to a 35 than a 50 neither is worlds apart. As such, the Summicron 50, available in a number of versions, is a competent option. Most of them will behave similarly to the Summicron-C 40. My experience is with the still current fifth version which has an overall rendering that's quite comparable. The absolute performance of the Summicron 50 V is slightly higher and more balanced than that of the 40. Ergonomics are worse and it’s a much larger, heavier and expensive lens.

Read the full review of the Summicron 50 V

Voigtländer Nokton 40/1.4

I’ve shot this lens extensively and it’s my other favourite 40. Both the Summicron-C and the Nokton have their respective advantages and disadvantages when compared to each other. The choice between them is not quite clear cut, but a close call between two great lenses. I’ve even put together a separate article comparing the two.

Read my full review of the Nokton 40

Zeiss ZM 35/2

I’ve not shot this slightly wider lens by Zeiss, but have used a few of their other offerings. The ergonomics are comparable, but the lens is bigger and heavier. Resolution is probably similar. The fantastic Zeiss coatings likely results in better transmission of light, better suppression of flare and appealing colour.




Bottom line

The Summicron-C 40/2 is a lens that’s quite a bit better than aspects such as price, size and specifications suggest. While not as even in performance as more modern designs, it delivers where it matters and equals many far more expensive options. It has a beautiful rendering with great colours. Stopping down gives practically perfect results. Additionally it almost disappears in use, thanks to its small size. It has some minor drawbacks, but nothing that really matters a great deal in actual use.



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All photos in this review were taken by me, using Leica CL & M9, Sony NEX-7 & A7. Exif-data is intact. Open any image in a new window for a closer look.