This lens has been around for quite some time in one form or another. This particular Version II Pancake was released in 2004 and hasn’t seen a revision since. I think it could do with a facelift, but optically it leaves little to be desired except for a few minor niggles. It's a lens I only came to appreciate once I compared it to newer and more expensive lenses for the Leica M mount, and in essence it has a fantastic performane to value ratio.

The Color-Skopar is tiny! It makes a Leica M body almost a pocketable camera. Personally, it's a little too small for my liking, since designing a lens this small will force a compromised design somewhere; If not optics then in the physical design, or both. For me, this compromise is obvious in the physical design and usability.

Being a pancake design, everything is geared towards being small. The aperture and focus rings are thin and a little fiddly to use. The focus ring is only usable with the finger tab, and the winged aperture ring often leaves the fingers hunting around to find them. In general, I don't like winged aperture rings on a lens since they provide only two positions to grab onto versus a concentric ring which can be grabbed at any position.

Optically, there’s the obvious compromise in that a lens this small isn’t going to be a fast one. But it isn’t very slow either, at only 1/2 stop away from f/2. It’s smaller yet faster than the Zeiss Biogon-C which is a f/2.8 lens. It’s faster and not much larger than a Leica Summaron 35mm f/3.5. Otherwise this lens’ optical attributes are very good and arguably quite underrated. It’s certianly sharp, but that doesn’t count for everything.

Unfortunately the older lens design brings with it some usage caveats. Focus shift needs to be accounted for and also a minor colour shift towards the edges. On the M11, uncoded, it shows a cooler rendering at the edges. This isn’t a strong shading, but it’s enough to notice on more mono-toned subjects and it can add additional steps to post processing. I haven’t found a suitable lens code that reduces or eliminates this. I understand that not everyone is willing or capable of removing the lens shading, which is why I hope Voigtlander can revise this lens’ optics without sacrificing too much of it’s original size and performance.

What makes this lens a little more old-school in rendering, at least compared to modern lenses, is a gradual contrast and sharpness fall off towards the edges. As one stops down, the contrast picks up quickly but overall less so than modern equivalents, like the Voigtlander Ultron 35mm ASPH II. Unfortunately, the Color-Skopar has focus shift, and even as a wide angle, it’s easy to have the subject slightly out of focus at f/5.6. It's annoying and this makes some modern lens designs far more attractive. It was the largest motivator for my purchasing the Voigtlander Ultron 35mm ASPH II. I think many photographers have become accustomed to focus shift, but I think the photographic world would be better without it. 

Another trait to note is that the lens has some moderately strong field curvature.  The image below depicts the field curvature shot at f/4 at a distance of around 5 meters. This makes shooting landscapesor planar objects a little tricky, but the plane of focus becomes even enough by f/5.6 to have relatively even performance across the frame at infinity. It's improtant to be aware of this field curvature, and to work with it for optimum sharpness. Luckily, focus shift generally keeps the centre focus further back (towards infinity) when stopping down, which brings the mid zone closer in line to the point of focus. It balances out so to speak. 

I bought the Voigtlander Ultron 35/2 ASPH II becuase I didn’t want to deal with the Color-Skopar's focus shift. But now that I have both, I’m hard pressed to say which one I prefer. The Ultron has this annoying mid-zone dip up to f/5.6, until which astigmatism makes for a bothersome rendering and crossover from centre to edge. By comparison, the Color-Skopar 35mm has a much less prominent mid-zone dip and its sharpness and contrast improves relatively evenly throughout the frame as one stops down. For me, both the Color-Skopar and the Ultron are both good enough from f/5.6 for Planar subjects. At apertures wider than f/5.6, both seem to have their drawbacks but it’s going to be subjective as to who will prefer what. Either way, at apertures wider than f/5.6 I wouldn’t place the subject too far off centre. I slightly prefer the rendering of the Color-Skopar at wider apertures with its even fall-off of sharpenss and contrast towards the edges. I don’t like the uneven image draw of the Ultron which is sharp at the centre, blurry at the mid zone and then sharp again at the edges. 

Ergonomically I’m drawn the other way again to prefer the Utlron. The Color Skopar embraces it’s pankake design a little too much for my taste and this results in an over-fiddly lens to use. But this is also subjective and not a fair negative aspect, as some would embrace its compactness, and for that it’s excellent.

I mentioned earlier about lens shading. It isn’t very obvious in the above uncorrected images, however in more monochromatic or evenly toned scenes it can be apparent. On the M11, the lens renders a little cooler towards the edges of the frame, even coded in camera as a Summarit-M 35mm f/2.5. For most images I’m not too bothered by it, but there are exceptions and the additional steps to edit it out can be a little annoying. The amount of shading can probably vary depenending on camera model, and it’s likely that earlier cameras like the Leica M9, M10 and M10-R may show stronger shading than the M11 with its BSI sensor. In post processing, a simple radial filter can be used to even out the colour temperature. I would recommend experiementing with different in-camera lens coding to find the best match. I’ve coded the actual lens with a stencil for a Summarit-M 35mm f/2.5, but it doesn’t do much for the cooler edges.

Lastly, the Color-Skopar lens has a low and unobjectionable amount of barrel distortion. It's a hair more than that of the Ultron 35mm ASPH, but still low enough that one probably won’t need to correct for it in most sittuations. Like many M lenses, the Color-Skopar has some strong vignetting that will probably need some form of correcting, either in post or as a form of in-camera lens coding. Uncorrected it’s exceedingly obvious, but not as obnoxious as the Ultron 35 ASPH.  See the image series below. 

In conclusion, the Voigtlander Color-Skopar 35mm f/2.5 PII offers an extrodinary performance to value ratio. Its small, relatively cheap and offers fantastic imaging that rivals and exceeds that of lenses much more expensive. It’s obvious compact design might not be ideal for everyone, but for those on a budget or in need of a compact lens that doesn’t compromise in image quality, this lens is that little hidden gem. I find the focus shift is it’s biggest set back preventing me to recommending it outright. But if you get the chance to try it, do it. I’m sure you’ll like it!