There are people who use FSU lenses on Nikons.
The J12 (35mm) does not fit easily on all Kievs (or Contax) this will also apply to Nikons, and some will scratch Nikon facia plates. The fit problems may be alleviated if you are practical with Swiss files and watchmakers screwdrivers set, dont worry it is only the J12 that you file and screw driver. The error (difference) in the focusing cam wont be (much of) a problem. After you finish the fit filing the J12 be easy & it will focus ok with the wheel if you want.
The J12 is a double gauss symmetric lens, and may need a clean, and more black paint (both internally and externally), one needs a small pair of pliers to do this internal paint. It does need great care. Even when clean and painted it can still flare, - pronounced iris images are typical.
The Helous 103 can be used at or near infinity with the rangefinder as it is, or can be easily adjusted to be ok at six or ten foot, (but then out at infinity) only a small screw driver set is required. It is more difficult to replace its spacer to alter its its focal length to the Nikon (Leitz) standard, which would allow rangefinder coupling at all distances on a Nikon, but would disable its similar use on a Kiev or Contax, this wont alter resolution performance too much, as the lens is so symmetrical.
The 103 is a double Gauss like the 2000 f/1.4 Nikon lens. It seems to be a rip off copy of the Mandler designed Summicron, a high refractive glass six element in four groups with two plane (internal plass to glass) surfaces for ease of (cost effective - cheap) manufacture. The Zeiss f/2 lens for G or Z are rather similar. High contrast very well corrected. The 103 (all the copies I've seen) are missing black paint that would have helped in high contrast situations, it can flare, though it is more difficult to provoke this, than with the J12, you get radial lines from light sources, some way separate from the source.
The 103 will give different out of focus effects from the sonnar clones, it will be more like the post 2000 Nikon lens.
If you are in to 'dabbling' or really poor any of these FSU lenses are interesting performers but the pre 103 Kiev lenses are pre WWII (sonnar) designs, - the edge performance is poor at large aperatures. The J8M or J3 (FSU 5cm) are sonnar clones and high contrast, especially if you paint them (internally). They are not as flare free as a Nikon, some of the J8 do come painted at the factory, even the ones that are 'unpainted' will do well 1/3 of s stop from wide open.
If you are just taking snaps and have only paid 30 USD for your Kiev (and lens) they are stellar performers. If it is a present for a seven year old expect real photos... And you will be able to fix other cameras.
I've only troubled to paint one lens internally and that only because it need the fungus removed, and was in small pieces.
Noel
