john_s Posted May 26, 2008 Share #1 Posted May 26, 2008 Advertisement (gone after registration) I'm wondering if my M6 bodies need adjustment, or perhaps I'm being too fussy. The basic problem is: my old M6 focusses my 50/1.4 ASPH perfectly at infinity and also at 2.5m which is a distance I use a lot. My old Summicron 50/2 and new Summarit 75/2.5 also focus just about perfectly at infinity and 2.5m. My Summicron 35/2 (ver 4) and 35/1.4 ASPH and Zeiss 25/2.8 all focus perfectly at infinity but they all front focus quite a bit at 2.5m. The 35/1.4 ASPH has had a trip to Solms where they did some adjustment (maybe very little) and it still seems the same to me. All lenses were bought new and have had a very gentle life. My tests have been done with tripod, ISO=25 film and cable release. I have repeated them several times consistently. My later M6TTL is very slightly different but basically the same across all lenses. My question is: is my problem that the bodies need adjustment? But I don't want the focussing of my 50/1.4 to alter. Can a body focus 50mm lenses and longer well, but at the same time the shorter focal lengths not at all well? Link to post Share on other sites More sharing options...
Advertisement Posted May 26, 2008 Posted May 26, 2008 Hi john_s, Take a look here Adjusting a rangefinder that's good with some lenses. I'm sure you'll find what you were looking for!
luigi bertolotti Posted May 26, 2008 Share #2 Posted May 26, 2008 Sorry, no advice from me... but I feel relieved that these problems of focusing aren't limited to M8.... Link to post Share on other sites More sharing options...
Dan States Posted May 27, 2008 Share #3 Posted May 27, 2008 John, if your camera focuses correctly with longer lenses it is probably fine and the issue is with the wide lenses. Both your 35 Summicron V4 and Summilux ASPH have a bit of focus shift, so if they focus ok at full aperture I would leave them alone. If they front focus at full aperture they will need adjustment. I'm surprised about the Zeiss. How much is it off at full aperture? Best wishes Dan Link to post Share on other sites More sharing options...
tobey bilek Posted May 27, 2008 Share #4 Posted May 27, 2008 It is impossible to get it all perfect for several reasons. first the camera and lenses are made separately and each has its own tolerences. The tolerences may cancel each other or stack up in one direction or another adversly effecting the focus point or the might both be "perfect.". When I knew a knowlegable Leica rep, he advised sending lenses like the 50 1.0 and 75 1.4 with the mating cameras and have them set to work together to nullify tolerence stack up. After the most critical lenses are set, 35`s and so on should not present a serious problem. One exception, 35 1.4 ASPH have a focus shift as you stop down. Therefore focus will be different at 1.4 and 2.8 and 5 feet. It is impossible to compensate for the shift with a rangefinder. Figure how much shift there is and compensate by moving. There is also field curvature. Focusing in the center and swing the camera to recompose will throw focus off. Even with macro lenses and enlarging lenses, Leica has never tried to optimise field flatness at the expense of other aberations. The sole exception being the Focotar with the large front element having a dead flat field. That was actually a Schneider lens though. Focotar 2 was back to a slightly curved field. Forgot, the 50 1.0 also focus shift as you stop down. Then the problem with film and digital appears. Film is not flat and focus is set to some point towards the center of film channel debth. With digi, there is a flat surface where the pressure plate used to be. Therefore lenses set to film specs will not be perfect for digital. More than you wanted to know. Sorry I might add, the two calibration points for the RF are infinity and 1 meter from the film plane. This is what you should check Link to post Share on other sites More sharing options...
john_s Posted May 28, 2008 Author Share #5 Posted May 28, 2008 John, if your camera focuses correctly with longer lenses it is probably fine and the issue is with the wide lenses. Both your 35 Summicron V4 and Summilux ASPH have a bit of focus shift, so if they focus ok at full aperture I would leave them alone. If they front focus at full aperture they will need adjustment. I'm surprised about the Zeiss. How much is it off at full aperture? Best wishes Dan My tests are all at full aperture for two reasons. Firstly, it is the most revealing test and if it's ok at full aperture it's going to be ok at smaller ones. Secondly, I take a lot of pictures indoors in light that requires full aperture. The Zeiss 25mm, the Summicron 35mm and the Summilux ASPH 35mm all front focus by about the same amount at 2.5m: that is about 350mm. It is most critical with the 1.4 lens, of course. I have just sold the Summilux 35mm (since I've found that I prefer the compactness of the Summicron 35mm and I use it far more). I like the 1.4 aperture of the 50mm a lot, though. I think I'll just learn to focus the remaining two wide angle lenses by remembering what they're actually doing. Having the bodies adjusted might ruin the current perfect focus of the two 50mm and the 75mm lenses. This is the perfect cure for acquiring many lenses that one might not use very much! Link to post Share on other sites More sharing options...
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