Sonnar 3,5/135 was my favourite lens on Praktica. It was light, compact, robust and well-executed lens with its wide focusing ring. The built-in lens hood was bit loose, but that hardly mattered. Optically, there was little to complain about. This actual specimen was bought new in East Germany by my father in eighties - it's about twenty years old, still going strong. I bought second hand Contax Sonnar 135 to be able to use this focal lenght without M42-C/Y adapter. The lens is considerably bulkier and heavier than its CZJ counterpart, which is understandable, considering it's f/2,8 maximum aperture. Optically it did not appear to be clearly superior to CZJ.
After going digital with Canon EOS 20D, the CZJ Sonnar saw a lot of use turning out fantastic results, highly detailed with great color rendition. The Kyocera-made Sonnar was not different enough to make it worth the hassle with adapter and was not used all that much.
Focus point is on the curtain, which means it is slightly behind the plane of the window and also behind the bars. The intent is to evaluate center sharpness, though right upper corner provides some detail as well. Self-timer and mirror lock-up was used for stopped-down shots.
Left CZJ, right CZ.
Unfortunately, I underexposed the CZJ shot. Apart from that, both pictures seem to show equal amount of detail.
Left CZJ, right CZ.
At the corner, the faster Sonnar is noticeable better, showing better detail. But also noticeable is some chromatic aberration along the vertical edge of the window.
Left CZJ, right CZ.
CZ lens show quite visible diffuse purple halos about bright objects, while CZJ picture shows hardly any CA.
Left CZJ, right CZ.
These two pictures are very much alike, one would be hard-pressed to tell them apart.
Left CZJ, right CZ.
Resolution-wise these pictures are very similar. Some (fairly minor) red/green fringing can be seen along vertical edge of the window in the CZJ image.
As far as resolution is concerned, the lenses are quite close to each other, with the exception of wide open CZJ being outperformed at corners. CZ Sonnar shows chromatic aberration in the form of purple halos at wide aperture, while red/green fringing of CZJ Sonnar seems to be more apparent while stopped down.