Leica Summicron M 40mm f/2 was a rather short-lived lens. Originally designed for the equally short-lived Leica CL, the lens was manufactured by Leitz from 1972 through 1977. I don't have full details about why this lens was discontinued - some argue that the lens was affecting the sales of more expensive lenses in Leica's lineup, others point to the lower margins that the C lenses carried, making them less profitable for the company. Whatever the reason was, C Summicron is a history now, with no direct descendants, at least from the Leica side. The lens has never been as popular as its 50mm version and up until recently good quality copies could be found for ~US$400.
The optical construction of the lens consists of 6 elements in 4 groups, following conventional symmetric Gauss design. The lens barrel is metal, as are the focusing and aperture rings. The focusing ring is fairly narrow, but has a tab which makes focusing operation somewhat easier. The aperture ring clicks in 1/2 f-stop increments, with f/16 being the min aperture level. The lens is tiny, measuring only 46 x 22mm (1.81 x 0.86in) from the base of the mount.
The lens weighs 125g (4.4oz), making it the lightest among all Leica lenses ever produced. The filter thread is 39mm but has 0.75mm pitch, which means that regular 39mm filters cannot be screwed on all the way in - do that and you risk damaging the threads. Leica's proprietary Series 5.5 filters can be used without any problems. The minimum focusing distance is 80cm (2.6ft).
Within the scope of this review, C Summicron 40mm f/2 was tested on an APS-H type Leica M8. Since the lens was designed for traditional 35mm cameras, its EFOV on M8 is equivalent to 53mm lens. The lens can also be used on Miccro Four Thirds and NEX cameras, with EFOV of 80mm and 60mm respectively.
|Lens Composition||6 elements in 4 groups|
|Angular Field||57 degrees|
|f-stop Scale||f/2-f/16, manual|
|Filter Size||Series 5.5|
|Lens Hood||Rubber (included)
Leica C Summicron 40mm f/2 is somewhat an unusual lens. As mentioned earlier, the lens was originally designed for the entry-level Leica/Minolta CL and carried a much lower price tag compared to other Leica lenses of that time. Two other lenses introduced by Leica for CL series,C Elmar 90mm f/4 and a very short lived C Elmarit 40mm f/2.8, also carried lower price tags, targeting new entrants into the rangefinder world. To avoid brand name and price dilution for the rest of the product line, Leica has been claiming that the lenses developed for the CL camera were not fully compatible with regular M cameras, allegedly because of different coupling cams on the C lenses. Over time this claim was dissolved, thanks to numerous practitioners who have been using C Summicron on their Leica M cameras with great success. As far as I am aware, there are no reported incompatibilities with C Summicron and the lens works perfectly fine with all film as well as digital bodies.
ISO 160, 1/750, f/2, 40mm (Leica M8(
Interestingly, Leica C Summicron, which was manufactured by Leitz in Germany, also had a direct copy-cat version (actually a legally licensed copy) - Rokkor 40mm f/2 CL, manufactured by Minolta in Japan. However, while Leica discontinued C Summicron in 1977, Minolta continued manufacturing Rokkor and even refreshed its 40mm lens version, adding multi-coating (the original C Summicron, as well as Rokkor CL were both single coated).
The lens is fully rangefinder coupled, although with exception of Leica/Minolta CL and Voigtlander Bessa R3, no other M compatible camera has 40mm frame-lines. On M8/M9, C Summicron brings up 50/75 frame-lines. Many dislike this and either machine down the lens mount to force 35mm frame-lines or simply use frameline selector, which is what I used to do until I got tired of constantly pushing the selector up and down. Lately, I just rely on the 50mm frame-line and visually extend it by a millimeter or so to visualize the 40mm frame-line. It's not 100% accurate of course, but is adequate for my personal use.
As all pre M8/M9 era lenses, C Summicron is not digitally coded. While you can use the sharpie marker to code it as a 35mm Summicron or even as a 50mm Summicron, the markings will get smudged over very quickly - C Summicron's mount if flat and does not have a groove like with some Zeiss and Voigtlander lenses which would protect markings from being erased when attaching/detaching the lens. The only option here is to either send the lens to Leica for after-market coding, or replace the mount yourself. I have not tried either of these options and do all artifact corrections in post-processing, using Photoshop, so I can't really comment on how well M8/M9 built-in firmare can correct various artifacts like vignetting or color drift.