Basic Camera Repair Information
Lens-to-film distance critical for sharp pictures

   Lens-to-film distance is critical on any 35mm camera. If the distance is off even 1/10th millimeter it can affect picture sharpness. If you shoot all your photos at small f-stops with wide angle or normal lenses, you you may not notice if the camera is slightly out of adjustment. But sharpness quickly falls off at larger apertures and with longer lenses that have less depth of field.
  Don't assume the LTF distance on any old Soviet camera is correct. Some cameras apparently came from the factory set incorrectly.
   On Zorki and FED cameras the lens-to-film distance is 28.8 millimeters. The distance is measured from the top of the lens mount to the film pressure plate. Actually, the distance should be to a piece of film on the pressure plate. On bottom-loading cameras the shutter release must be held down while on the "Z" or "B" setting to access the pressure plate from the front of the mount.

  The distance is adjusted by adding or removing thin paper shims between the lens mount and the camera body. The measurments can be made with a caliper or by making a probe of the right length using a camera with at LTF distance that is known to be accurate.
Rangefinder adjustment
 Rangefinders can get out of adjustment both vertically and horizontally (distance). The Zorki 1, C and 2C models have identical adjustments. To set horizontal adjustment set the lens on infinity, look through the rangefinder and use a small screwdriver to adjust the two images so they merge. To get the images in alignment vertically the inside ring of the optical wedge must be used to make the images merge.
This diagram done by Jim Blazik, shows how the shutter curtains, ribbons and drum should be aligned to replace curtains on a Zorki or FED when the originals have become detached, leaving no reference point for the new curtains.
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