A fairly common issue on online forums with the Fed rangefinders seems to be rangefinder accuracy. When I first bought my Fed4, the rangefinder patch did not align accurately either at infinity or at closer distances.
Luckily the rangefinder is fairly easy to adjust – although I could only find guidance for other models, so I thought I’d briefly outline the steps I used to adjust the rangefinder on my Fed4. As with any type of maintenance on old cameras and lenses, you follow these guidelines on your own equipment at your own risk.
First I removed the metal name plate at the top centre of the front of the camera (just above the lens) – which is held in by a couple of clips. To do this, I used the end of a wooden chopstick (whittled down slightly) and carefully inserted it a little into the hole in the front of the name plate. I then moved it slightly to one side so the plate was free of the clips – some people say the clips have a tendency to fall out as well but mine stayed in place.
When I removed the name plate I could see the rangefinder lens surrounded by a brass collar and a hole containing an adjustment screw (flat-headed). Adjusting the rangefinder calibration involves rotating the collar around the rangefinder lens and the adjustment screw.
The collar around the rangefinder lens on my Fed4 was held in place around its edges by some dried up shellac (I think it was shellac). I carefully scraped off the shellac with the end of a small screwdriver.
I then went outside, set the lens to infinity and pointed the camera at a far-away object. Using an old pair of dividers for the adjustment collar and small screwdriver I set the rangefinder patch so it aligned correctly at infinity. Both only required small adjustments.
I then took the camera inside and set the lens at its closest focus distance and used a tape measure to place the camera that distance from a close object. Using the adjustment collar and screw I set the rangefinder patch so it aligned correctly at the closest focusing distance.
I then needed to repeat the process a couple of times, as adjusting the rangefinder at one end of the focus range slightly affected the alignment at the of the rend of the range. However it only took a few iterations to get the rangefinder patch accurately aligned throughout the focusing range.
I did not try to secure the collar around the rangefinder lens with anything to replace the shellac I had scraped off – mainly because I thought it might make it harder to re-adjust the rangefinder if necessary. I then replaced the Fed4 name plate (again using a chopstick in the hole to help). Easy.