Rangefinder/Lens Test Guide?

[nation_of_pomation]

Hey. Does anyone think they could point me to a decent guide to how I can check the rangefinder in my FED-5B and also the I-61 L/D that came with it? One or both of these aspects of my camera seems to be off, my test roll came out with lots of my photos focused too short, when I was very sure the rangefinder was giving me the green light, on photos shot at f5.6 and bigger. If one of those doesn't exist, someone with the know-how should definitely make a sticky out of one, that would be really helpful for ignoramus hobbyists like myself.

 

[wolves3012]

You need to check the RF at infinity and also at 1m to get it right - and that assumes the lens/mount are correctly set up (not guaranteed but they're likely to be close).

Find a very distant object, preferably something like a tree or TV arial on the horizon and make sure the RF says it's at infinity. An excellent target for this is the moon or a star at night but whatever, make sure you use something 500m+ away.

If that's ok, also check the 1m focus. Measure 1m from the film plane (a couple of mm closer than the back of the camera) and place a target there. Focus on it and check the lens scale reads 1m.

If either of the tests above doesn't give the right result, you need to adjust your RF. There's a sticky that tells you how. It's tedious, be warned. Once the RF is known to be correct, any errors in focus will be down to the lens or lens mount not being set to the correct lens-to-film distance or "operator error".

 

[nation_of_pomation]

Thanks! I'll definitely do that. What exactly about the lens mount could be wrong/what would it do to the camera/resulting photographs? Also, I just realized there is a diopter around the VF of the 5B. Could that have been adjusted improperly? I started fiddling with it and it went out, in, and back out of focus as I twisted it. Is that for people who need glasses? I don't, so maybe the last person to own the camera messed with it. Just a thought.

 

[Penny Lane]

The lens mount is shimmed to 28.8mm from the film plane. If this distance is upset by mere fractions of a millimeter, you focus will be off which is especially noticeable at larger apertures.

IIRC, the tolerances at the factory were something like 28.80mm + .02/- .03 or thereabouts... There should be a download for an English version of the Maizenberg book floating around here, that should clear things up a bit.

Edit to add: Found it. 1st post: http://www.flickr.com/groups/ishootfilm/discuss/72157626640046768/

Derk

 

[wolves3012]

The lens mount is set as Penny Lane indicates, at 28.80 +/- 0.02mm. This is achieved with shims under the lens mount itself. In addition, the optics module of the lens also has a shim, to ensure the optics sit at the correct position. Either of these can be off and cause errors. However, there's a reasonable chance this is not so on the FED 5, most are ok.

The diopter adjustment you mention is, indeed, to correct for eyesight. Just turn it until the image appears sharp and leave it alone after that. It has no effect on the RF accuracy, at least within your ability to see the RF patch clearly enough if you mis-adjusted it.