The huge price difference between Zeiss lenses and Kiev, Jupiter and other Russian made lenses with Contax lens mounts makes them appear to be an appealing alternative to expensive Zeiss lenses.
Optically the Russian lenses can be fantastically superb, but then they can also be very bad. There is a great variation in optical quality. This is why they are so cheap. Luckily the lenses are cheap enough so that one can afford to buy four or five of them in order to get one that is optically extremely fine. But then you can also be very unlucky and get five really bad ones in a row. This is also possible. The Kiev Camera Company used to run an advertisement in Shutterbug magazine that read, "Did you loose at Russian Roulette?" to describe the quality range of cameras and lenses imported directly from Russia.
Mechanically the Russian lenses are of very primitive design and the quality of the components is very low. The lenses are usually fabricated of the softest grade of aluminum instead of brass. The lubricant used is a form of wax and while it does not deteriorate because it is a wax instead of a grease, it also doesn't lubricate very well and gives the focusing a rotten stiff feel.
The main problem with the mechanical components is that they appear to have been fabricated by people who really did not care about what the outcome of job was. Many parts that require a very fine finish in order to slide easily are finished roughly. It is possible to improve the parts, but the amount of elbow grease and just plain hard detail work it takes to do this is very large, and in the end the cost would probably wind up being greater than it would be to just go ahead and purchase a Zeiss lens anyway.
Many lenses are not set properly and do not focus at infinity. You can count on one thing for sure with a Russian lens and this is if you do not have a very lucky purchase you will definitely have the nagging thought the lens needs a good servicing.
When you are thinking of purchasing that extra lens keep one thing in mind. The exterior cosmetics are insignificant if the front and rear lens elements are clean and are not scratched. You can save a lot of money on a superb Zeiss lens by waiting your time and waiting for a good well used optically perfect Zeiss lens to come along on Ebay. You can save a great deal of money if you are willing to do with less than Mint cosmetics and just focus on the picture taking quality of the lens.
I service Russian lenses.