Just as a matter of interest, vibration levels with SLRs is a bigger problem than most people realise. I do not use 35s as my main camera, and when I do I use mainly Pentax. I have, however, toyed with numerous Nikons, such as a second-hand FE, F3 and FM, all of which I sold on fairly quickly because of the vibration level. It was only when I bought a new FM2n a few years ago (and the FM3a I have now) that I felt I was getting properly sharp pictures.
Originally Posted by Stephanie Brim
As a general rule, I would say anyone with an SLR more than 10 years would seriously upset themselves if they were to shoot a series of pictures of the same subject with the same effective exposure, changing the shutter speed from 1/500 one step at a time down to 1/30. It is more than likely they would see sharpness decreasing from 1/250 downwards.
Rangefinders like your Fed are of course unaffected by mirror vibration, as they don't have mirrors, and most of the shutter vibration seems to be generated as the shutter stops after the exposure. Engineering to Leica standard can take vibration levels down very low with rangefinder cameras, although I feel that only a leaf shutter can have zero vibration (because all its moving parts are concentrically balanced).