Contax 85mm CA


TPF Noob!
Aug 18, 2014
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I’ve been building a set of Zeiss Contax for filming. I’ve a 21mm 2,8 28mm 2,8 35-70mm and the 80-200mm. they all perform very well but collecting old lenses of E-bay is hit and miss and these are not necessarily the first copy’s I’ve been through. I’ve sent them back with fungus a few times and odd mists but I just received a 85mm 1.4. This lens is in absolute mint condition with all the original packaging, even the packaging is in mint condition. The focus and aperture are super smooth, I thought my other lenses were smooth until I got this one and the glass is without a single detectable blemish. It’s a reasonably late model, serial no 7156019, an MM but made in West Germany, no ninjas.

I do a test shoot for all the new lenses and with this one I was a little surprised. It’s soft WO but that’s to be expected at 1.4 I guess, I’ve never had a lens faster than 2.8 before, but it shows horrible CA all the way up to f2.8 not clearing up till 5.6.




Here is the 21mm at 2.8

And here is the 28mm at 2.8

I'm a little shocked, does anyone know if this is a bad copy? Or am I just missing something? Is it something to do with how I took the pictures? They are all 100% crops from Jpegs. The Jpeg’s are taken from raw files with nothing altered apart from slight exposure adjustments.
Once a person starts looking at 100% crop sections, stuff like simply atrocious CA at f/1.4 and horrible CA at f/2 become part of the pixel-peeping experience. The bright white building and the super-strong geometric lines are perfect subject matter to show this CA. A number of very fine lenses will show color fringing at wide f/stops, especially around the edges of solid white things...105 DC Nikkor and 135 DC Nikkor show super-strong color fringing at their widest two f/stops... f/1.4 is extremely difficult to fully correct for CA.

Did you try running CA removal in your raw converter? It looks like some of that could probably be corrected in software.
Thanks for getting back to me I was unsure if anyone could see the images, I’ve just a little symbol on my screen. I’m shooting here in strong sunlight at f1.4 so it is an extreme situation but I tried some other tests and it showed up anywhere that the image is blown out, reflected sunlight off metal or shiny surfaces especially. I may be able to correct it but for filming I wouldn’t bother it would be too much hassle. The crop is just as an example, at 2.8 and below it’s very clearly obvious in the full image. It’s just that no other Contax lens I’ve owned has done this before so I’m unsure if this is just the nature of the 85mm lens or if there is a problem? Do some older lenses of the same type show more CA than other or is this not a fault that can happen, are all examples of the same model equal in their CA?
I'm going to say that yes, pretty much all models of that lens will have very similar, almost identical CA profiles. The longer a lens's focal length, the more likely that it will be unable to precisely focus all wavelengths of light to the same *exact* point of focus. The longer the focal length of a lens, the more magnified its images, and the larger picture elements tend to be; with a 14mm lens the edges of the white material would be very small, and hard to see. The longer the lens length, the easier it is to see optical issues like fringing on the edges of bigger stuff. An 85mm lens is plenty long enough for CA to be seen in regular, everyday photos; in wide-angle pictures of low magnification, CA tends to look a bit hidden.

Years ago, many people shot 35mm film for small print and color slide projection, but most pictures were seen small; today we can pixel-peep and see segments of photos that are, at 100% pixel size, as big as a common front door. Leica has an expensive 75mm f/2.0 apochromatic that can probably shoot fringe-free. It's $3200 or so. Zeiss makes the new 135mm f/2 APO-Sonnar, which is basically FREE of any color fringing. The Nikkor 200mm f/2 AF-S VR and VR-II lenses are almost totally free of any color fringing,at every aperture; it takes exotic,expensive, difficult-to-manufacture optical designs to eliminate all traces of CA in longer focal length lenses. Canon's expensive 85/1.2-L has a lot of longitudinal CA when shot at wide f/stops. "Regular" 85mm f/1.4 lens designs that are 35 to 20 years old and which sold for normal prices are probably all going to have some CA visible under some picture-taking conditions at wide f/stops.
I’ve owned lenses this long but never this fast before, I guess I just needed someone to tell me I’ve my knickers in a twist. If is the nature of a long prime then I’ll just have to shoot around it. Thanks for taking the time to explain this, N.

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