is the opton made for a nikon or contax mount? There is a slight difference, which doesn't matter much for 35mm and wider, but with 50 and up does make a difference of focus shift.

You can find a full discussion here...http://www.cameraquest.com/NRF-Contax.htm

and keep in mind that the Kiev was made by Ukranians using the Soviet system of "Quality is Job 2!"