I have I Pentacon Six wich comes with the Carl Zeiss Jena Biometar 80mm 2.8. The camera has some problems so I don't use it but one day I though "Why don't I get an adapter ring and use on my Nikons (D90 and F65). So I did. Then, a friend lend me a Kiev-60, to shoot a roll, and it came with an ARSAT C 80mm 2.8. Since they both have the same mount (usually called P6, for "Pentacon Six") and therefore fit my adaptor ring, and the ARSAT is supposed to be a copy of the Biometar, I thought it would be cool to compare them.
Obviously this is a very dodgy. To begin with, both lenses are for medium format, so even a full frame camera would not use them fully, so it would not make much sense to compare them. It’s even worse on my D90, because of the crop, because of the small sensor. And when I say “worseâ€, I mean “greatâ€, because I’ll be using the very, very best of the lens. Another reason why this is dodgy, as if the first was not enough, is myself: I don’t have a tripod with me, I am stuck in a small flat near Barcelona, I have to give the ARSAT back tomorrow and I am not really qualified to do this. But, hey, that’s not going to stop me posting some samples.
To begin with, three shots with the Biometar, at f2.8, f5.6 and f16. The focus is intended and therefore supposed to be on the winder, but with manual focus and small viewfinder it’s hard to be sure (the focusing LED from the camera doesn’t seem to be all that reliable).



Now the equivalent by the ARSAT C:



Another thing, in which lenses can differ substantially, in my tiny experience, is in color saturation and so on, so here are two shots at f4 and 160th at ISO 800 (as you can guess, my room has no window):
Biometar:

ARSAT:

I have shot more pictures that these samples, but these drawn to the same conclusion as all the rest: the two lenses, to me, seem to be identical: the contrast, the bokhe, the saturation, the flair, etc. When carefully looking at the pictures I though one may be ever so slightly sharper, but in the end I thought it was a slight difference in exposure (clouds changing lighting or something).
Probably you will have heard about the poor quality control in the USSR, but my ARSAT seems to be perfect and, ironically, it’s my German Biometar that has the DOF preview leaver broken and the focusing ring jams a little bit sometimes because of this.
All in all, the Ukrainians did an excellent job with the ARSAT C (can’t you tell I am Ukrainian myself?). The only noticeable difference I see (apart from the looks), is that while the ARSAT focuses from 0.6 and beyond, the Biometar does not focus closer than a meter, which can make a difference:


So if I had to choose, I’d take the ARSAT because of the focusing. This may not be a big deal when shooting it as I medium format lens that it is, but remember that on my DSLR it’s like an 120mm lens, a good portrait lens, and when shooting, say a portrait, one meter can be borderline if you like getting close. But since the ARSAT is not mine, I’ll have to stick to my Biometar.
Anyway, this is my opinion on these particular lenses that I have.
Take care.