popavvakum
Established
Hello, everyone,
According to the repair manual for Kievs (in Russian, available at ) the working distance in Kiev must be 31.85+-0.02mm; this distance is from inner bayonets of the helicoid to the film plane, i.e. inner rails. I assume that it is from the upper side, towards the lens, of those bayonets. The actual check prescribed by that manual is to verify that the distance to the plate of the back cover, i.e. the outer rails, is 32+-0.03mm. I measured the distance from the upper side of the inner bayonets to the film plate on Kiev-3A made in 1957: 31.86mm, Kiev-4 made in 1965: 31.88mm and Kiev-4A made in 1980: 32.00mm. Precision of these measurements is +-0.01mm. Clearly, the working distance of the last Kiev is too large by 0.15mm while the first two comply with the standard. Hence, my first question: how accurate are the working distances set in Kievs and are there any variations depending on the year? I am curious as to how their accuracy compares to Contax'es?
Rangefinders on these three Kievs are very accurate; the lens they came with, Jupiter-8 (1957) and two Jupiter-8M produce the sharpest image on the matte glass set on the inner rails, i.e. in the film plate, when the camera is focussed with the rangefinder. When the lens from 1980 is moved to another Kiev its sharpest focus position for image at about 1m away from camera does not coincide with the rangefinder focussing at F2.0 but the difference is such that at F2.8 the depth of filed cover it. The same happens if lens from 1965 or 1957 is moved to 1980 Kiev. Curiously enough, the infinity seems fine for any body/lens combination, that is my house-made matte glass and zoom I am using are not good enough to see the difference. Thus I am led to believe that the 1980 lens was shimmed specifically to its out-of-standard camera, rather than setting both to standard distances. The second question - is it common, that is what is the chance that a random Kiev or Contax lens, for example bought from a known bay, would be shimmed to a non-standard working distance? The Soviet instructions usually advise shimming of longer focal lenses to the camera but one may believe that 50 and 35mm lenses should be fine.
Vignetting and edge of frame sharpness are very different if the image in focus is brought to the edge of the frame by turning the camera, so the image plane becomes inclined to the plane of the film or by moving the camera parallel to it. When the image is at an angle to the film plane, both vignetting and sharpness are worse as compared to when it is off-centre but in a parallel plane. The third question - is it a manifestation of the view field curvature effect inherent in Sonnars or I should look at the centering of the lens elements (I had to re-centre the front elements of Jupiter-8 and 1980 Jupiter-8M)?
The same repair manual says that the lens resolving power is determined by photographing GOI patterns set at 1.5m distance, on 32 GOST (17 DIN) film developed in "standard AGFA developer" at 20+-1C for 12 minutes but "accelerated development is acceptable". The photos are to be taken wide-open, but no other details are given, but I would then assume that the resolving power is for the lens plus film combination therefore the lens alone would have a much better resolution. For example, if at 50 lpm the lens give 60% contrast and the film gives 60% contrast, the combination would only give 36% contrast, i.e. its resolving power related to 50% contrast would be less than 50lpm even though both lens and the film have better resolution than that. Hence, what is the resolution of J-8M alone? Rather suprisingly, I could not find any data on the internet other than the Soviet "30/14 lpm"; I am tempted by Helios 103 ("55/28 lpm") which is supposed to have much better sharpness both at the centre and the edge but confused by numerous reports that it is very poor at the edges.
I apologise for this long post, thank you for finding time to read it, and welcome your thoughts,
AB
According to the repair manual for Kievs (in Russian, available at ) the working distance in Kiev must be 31.85+-0.02mm; this distance is from inner bayonets of the helicoid to the film plane, i.e. inner rails. I assume that it is from the upper side, towards the lens, of those bayonets. The actual check prescribed by that manual is to verify that the distance to the plate of the back cover, i.e. the outer rails, is 32+-0.03mm. I measured the distance from the upper side of the inner bayonets to the film plate on Kiev-3A made in 1957: 31.86mm, Kiev-4 made in 1965: 31.88mm and Kiev-4A made in 1980: 32.00mm. Precision of these measurements is +-0.01mm. Clearly, the working distance of the last Kiev is too large by 0.15mm while the first two comply with the standard. Hence, my first question: how accurate are the working distances set in Kievs and are there any variations depending on the year? I am curious as to how their accuracy compares to Contax'es?
Rangefinders on these three Kievs are very accurate; the lens they came with, Jupiter-8 (1957) and two Jupiter-8M produce the sharpest image on the matte glass set on the inner rails, i.e. in the film plate, when the camera is focussed with the rangefinder. When the lens from 1980 is moved to another Kiev its sharpest focus position for image at about 1m away from camera does not coincide with the rangefinder focussing at F2.0 but the difference is such that at F2.8 the depth of filed cover it. The same happens if lens from 1965 or 1957 is moved to 1980 Kiev. Curiously enough, the infinity seems fine for any body/lens combination, that is my house-made matte glass and zoom I am using are not good enough to see the difference. Thus I am led to believe that the 1980 lens was shimmed specifically to its out-of-standard camera, rather than setting both to standard distances. The second question - is it common, that is what is the chance that a random Kiev or Contax lens, for example bought from a known bay, would be shimmed to a non-standard working distance? The Soviet instructions usually advise shimming of longer focal lenses to the camera but one may believe that 50 and 35mm lenses should be fine.
Vignetting and edge of frame sharpness are very different if the image in focus is brought to the edge of the frame by turning the camera, so the image plane becomes inclined to the plane of the film or by moving the camera parallel to it. When the image is at an angle to the film plane, both vignetting and sharpness are worse as compared to when it is off-centre but in a parallel plane. The third question - is it a manifestation of the view field curvature effect inherent in Sonnars or I should look at the centering of the lens elements (I had to re-centre the front elements of Jupiter-8 and 1980 Jupiter-8M)?
The same repair manual says that the lens resolving power is determined by photographing GOI patterns set at 1.5m distance, on 32 GOST (17 DIN) film developed in "standard AGFA developer" at 20+-1C for 12 minutes but "accelerated development is acceptable". The photos are to be taken wide-open, but no other details are given, but I would then assume that the resolving power is for the lens plus film combination therefore the lens alone would have a much better resolution. For example, if at 50 lpm the lens give 60% contrast and the film gives 60% contrast, the combination would only give 36% contrast, i.e. its resolving power related to 50% contrast would be less than 50lpm even though both lens and the film have better resolution than that. Hence, what is the resolution of J-8M alone? Rather suprisingly, I could not find any data on the internet other than the Soviet "30/14 lpm"; I am tempted by Helios 103 ("55/28 lpm") which is supposed to have much better sharpness both at the centre and the edge but confused by numerous reports that it is very poor at the edges.
I apologise for this long post, thank you for finding time to read it, and welcome your thoughts,
AB
