sixteen pads Posted December 22, 2019 Share #1 Posted December 22, 2019 Advertisement (gone after registration) Hello Team, The camera in question is the M4-2. Has anyone dealt with this kind of adjustment in the past ? I know for a fact that my rangefinder is adjusted properly. ( The camera was just CLA'd for that. ) I have done tests with many lenses. Some of which focus perfectly on other bodies. Yet the resulting photos come out soft on this particular M4. I am not sure if the camera is front or back focusing. I guess the next step should be to consider what needs to be done to the flange focal distance ? I would appreciate any info on this. Thank you I hope I am making sense. all the best Quote Link to post Share on other sites More sharing options...
Advertisement Posted December 22, 2019 Posted December 22, 2019 Hi sixteen pads, Take a look here lens flange to focal plane distance adjustment ??. I'm sure you'll find what you were looking for!
Michael Geschlecht Posted December 22, 2019 Share #2 Posted December 22, 2019 (edited) Hello 16, Why don't you begin by placing your camera on a tripod with each of the lenses & focusing on a meterstick/yardstick at 50cm/18inches. With the camera about 3 meters/10 feet away from the line of focus. Since this is a film camera first do photos with the camera set at F5.6 & see where the center of focus is. That is: How much in front of or behind the 50cm/18inch mark the actual focus is. If the rangefinder is accurate then the 50cm/18inches should be the sharpest with a little less sharpness in front of & behind the 50cm/18inches. With a small amount of greater depth of field behind the point of focus than in front of it. Try that first & let us see the results. By the way, the flange to film plane distance for "M" cameras is 27.8mm. Best Regards, Michael Edited December 22, 2019 by Michael Geschlecht Quote Link to post Share on other sites More sharing options...
adan Posted December 23, 2019 Share #3 Posted December 23, 2019 The acid test for lens flange/film-plane correctness is to avoid using the rangefinder at all (remove that variable altogether). Simply set each lens to its infinity mark (as far as the lens can be turned in that direction) and photograph something at least a couple of km/miles away. If things are sharp at infinity (i.e. a very long distance) when the lens is set to infinity (especially across several lens samples) the lens flange-film distance must be correct. Period. Now, if that shows a problem, there is not an "adjustment screw" or some such that a user can adjust themselves - the lens mount is screwed right to the solid one-piece camera shell. But there are some other things a user can check. First, open the camera back and make sure the pressure plate is sufficiently spring-loaded to press the film into the focal plane (onto the film rails). After 40 years, the springs could be weak, leaving the film sloppy and not in the actual focal plane. Then, check the camera's lens flange attachment screws to make sure they are fully tightened. A loose flange will #@#$% the flange-film distance as well. A complete and competent CLA should have checked and caught both of those - but you just never know.... A couple of other points: - if you shoot a test at infinity as described above, that should at least clarify if the camera body is causing front-focus or back-focus. If nothing in the pictures is sharp, the flange/film distance is too short, and the lenses are focusing "beyond infinity." If distant objects are fuzzy, but closer things are sharp (front-focusing), then you'll know the flange/film distance is too long. - it is possible that the camera's flange was "shimmed" when originally built, to be in the correct position (ELCAN had some early QC problems as they learned to build M4-2s in the late 1970s). If a service person over the past 40 years accidentally lost - or misreplaced - original factory shims, that could put the camera flange out of position. If you really want to mess with it yourself (preferably without piercing a shutter curtain with a depth-micrometer ) you can take the dimension Michael gave above, put some film in the camera, lock the shutter open with a locking cable release and the shutter set to "B," and measure the actual flange/film distance. If it is not at the correct spec, in theory you could remove the flange and add/remove shims yourself to get it to the correct measurement. Beyond that, I guess there is the remote possibility that the internal shutter/film-gate "core" (see center object in this image: https://petapixel.com/2011/08/22/a-leica-m4-rangefinder-disassembled/ ) - which slides in and out of the camera shell like a hand into a glove - was factory-shimmed into position. And that has gotten out of alignment. But at that point a fix means a complete disassembly and reassembly, possibly with shimming - and really needs to be done by a pro tech with the right equipment to re-test everything afterwards. Quote Link to post Share on other sites More sharing options...
wattsy Posted December 23, 2019 Share #4 Posted December 23, 2019 Some good suggestions from Andy for the OP but I find the original question puzzling – particularly the statement that "I know for a fact that my rangefinder is adjusted properly" but also that "I have done tests with many lenses. Some of which focus perfectly on other bodies". I can't help but feel that a number of assumptions have been made before leaping to the conclusion that the film plane to flange distance is wrong. What method did the tech doing the CLA use to adjust the RF and, if there is a problem with the flange to film distance, why wasn't this picked up during the adjustment procedure? I'm assuming that the tech would have used some kind of visual process (groundglass placed where the film plane is) to adjust the focus? Quote Link to post Share on other sites More sharing options...
250swb Posted December 23, 2019 Share #5 Posted December 23, 2019 Yes it's the "Some of which focus perfectly on other bodies." that is worrying. To remind the OP the lens should be adjusted to its own factory set datum point, and likewise the body should be adjusted to its own factory datum point. But they should never be adjusted together, that is the body/viewfinder is adjusted to work with a specific lens or visa versa because this is what leads to 'some focus perfectly on other bodies'. But many of the things Andy suggested could also be true. The basic infinity test suggested by Michael is the first thing to do, eliminate the obvious before doing anything else. Quote Link to post Share on other sites More sharing options...
sixteen pads Posted December 23, 2019 Author Share #6 Posted December 23, 2019 (edited) Big big thanks to everyone who took the time to respond and who shared their wisdoms. This is very helpful ! I will definitely proceed with the tests you all have outlined and will report back with my findings. Happy Holidays everyone. Edited December 23, 2019 by sixteen pads 1 Quote Link to post Share on other sites More sharing options...
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