I had a nice find from Russia while looking for some photo equipment: the Photo rangefinder DF (the “DF” probably stands for “Photographic Rangefinder”). It had a good price and it is just the right equipment for my Smena 8M. There was no much information about it except that it seems to be quite rare. According to fotoussr.ru it is a copy of the Smena rangefinder from GOMZ (State Optical and Mechanical Plant) produced at the MMZ (Minsk Mechanical Plant) for probably quite a limited time from 1957-1961.

I got it with a neat little leather case (instead of the usual plastic one), which was typically for the Leningrad Smena. I checked if everything worked and it looked pretty good: the wheel turned smoothly, the distance scale ranged from 1 meter to 10/∞ and was easy to read, and the double image was clearly visible. However, I noticed the calibration was way off. Everything above 5 meters read the same, and the scale between 1m and 2m was always off by about 0.5m. So I figured I’d try to recalibrate the rangefinder.

Boy, was this an adventure… There’s no manual (at least I couldn’t find one), so at first I just tried some trial and error. That only made things worse, and now I had a vertical misalignment too. Great - freshly bought and I’d already managed to break it. Luckily, I found a Russian YouTube tutorial where someone disassembled a Blik rangefinder, and I thought maybe the design wouldn’t be too different. So I disassembled my newly acquired rangefinder, used the distant späti as my ∞ point, and tried my luck with the arrangement of the mirrors. It was still a bit of trial and error, but the video helped me pinpoint the screws I needed to adjust. I put everything back together and replaced a few screws that had seen better days.

The upper right screw is only for vertical alignment but i think it is designed to not really temper with it at all. If the screw is too loose the vertical misalignment will happen more often over the time, although too tight is also not good either. If too tight the measurements from 3m upwards are whacky. It works if the misalignment is really only vertical and light. Only very few gentle screwing is needed (more like a hint of screwing, because slighty changes can bend the metal under the mirror and change the alignment more). When the misalignment is total out of place i got better results with loosen the downer left screw to adjust the mirror directly. However it is very very finicky as you have to also account for the slight alignment change if you tighten the screw back again but i got the best result from it when the misalignment was severe (like from ‘i accidently dropped it’).

The upper right screw is only for vertical alignment but i think it is designed to not really temper with it at all. If the screw is too loose the vertical misalignment will happen more often over the time, although too tight is also not good either. If too tight the measurements from 3m upwards are whacky. It works if the misalignment is really only vertical and light. Only very few gentle screwing is needed (more like a hint of screwing, because slighty changes can bend the metal under the mirror and change the alignment more). When the misalignment is total out of place i got better results with loosen the downer left screw to adjust the mirror directly. However it is very very finicky as you have to also account for the slight alignment change if you tighten the screw back again but i got the best result from it when the misalignment was severe (like from ‘i accidently dropped it’).

I set up a small testing range and checked the settings with my SLR cameras. It seems to be neatly calibrated again and works like a charm. Cheers to Soviet repairability.