goldchen96 Posted June 30, 2013 Share #1 Posted June 30, 2013 Advertisement (gone after registration) I will soon purchase a used but serviced M8 from a Leica Dealer. Trying out the camera in the shop I noticed back-focus with both 35 summilux and 1,0 nocti wide open. M8 and lenses are in Solms now for "calibration". As I do not really understand the technical process, will I face any problems focussing these two lenses correctly on my film M once they have been made to work "correctly" on the digital body? Thanks for any insight on this matter... Link to post Share on other sites More sharing options...
Advertisement Posted June 30, 2013 Posted June 30, 2013 Hi goldchen96, Take a look here Lens calibration/different M-bodies. I'm sure you'll find what you were looking for!
wattsy Posted June 30, 2013 Share #2 Posted June 30, 2013 The short answer is no, Leica are supposed to adjust to a standard independent of any particular body/lens combination. The longer answer is that there shouldn't be a problem but it has been postulated that Leica have revised their thinking in the years since the advent of the M8 about the significance of the flatness of the digital sensor vis-à-vis less flat film (which also has thickness). Link to post Share on other sites More sharing options...
tobey bilek Posted June 30, 2013 Share #3 Posted June 30, 2013 The short answer is no, Leica are supposed to adjust to a standard independent of any particular body/lens combination. The longer answer is that there shouldn't be a problem but it has been postulated that Leica have revised their thinking in the years since the advent of the M8 about the significance of the flatness of the digital sensor vis-à-vis less flat film (which also has thickness). This is more than speculation. Link to post Share on other sites More sharing options...
wattsy Posted June 30, 2013 Share #4 Posted June 30, 2013 This is more than speculation. Well it's either speculation or it's not. I'm not sure how it can be "more than speculation". If you think it's bollocks just say so. Link to post Share on other sites More sharing options...
tobey bilek Posted July 1, 2013 Share #5 Posted July 1, 2013 Unless you have a spy in the factory, you will never be sure. My experience from the 198x time was that focus was not set to register distance, but some space in the depth of the film channel knowing that film has thickness and does not lie flat. Therefore they hit a compromise. So the young M8 engineers not knowing history used the same jigs to set focus and put the flat sensor precisely at the old register distance. Result the lens focuses in front of the sensor. The fix is two calibrations, one for film cameras, one for digi. Not very good. They probably moved the sensor forward shortening the register. I can`t say you are wrong, But I know what I read decades back and put that with some speculation on my part. So it is still more than speculation, but not a fact as I do not have an inside connection. I really have no desire to get into a contest with someone. Link to post Share on other sites More sharing options...
120 Posted July 31, 2013 Share #6 Posted July 31, 2013 ...So the young M8 engineers not knowing history used the same jigs to set focus and put the flat sensor precisely at the old register distance. Result the lens focuses in front of the sensor. The fix is two calibrations, one for film cameras, one for digi. Not very good. They probably moved the sensor forward shortening the register. ... I know you labeled this as speculation, but I don't think there is any source suggesting Leica made any "mistakes," or ever moved the M8 sensor. That is just something made up by the forum. The standard is 27.8mm, and that is the working distance of the lenses. In the film cameras they located the rails at 27.95mm to have the film where they wanted it. In the digital cameras, they would locate the sensor assembly to have the appropriate layer at 27.8mm, where they wanted it. Some people had focus troubles when the M8 arrived, and the same for every previous model of M camera introduced; it should not require any special explanation. Link to post Share on other sites More sharing options...
jaapv Posted August 1, 2013 Share #7 Posted August 1, 2013 Advertisement (gone after registration) Any lens that focusses perfectly on a digital body does so as well on film. The tolerances are wider on film. Link to post Share on other sites More sharing options...
120 Posted August 1, 2013 Share #8 Posted August 1, 2013 Any lens that focusses perfectly on a digital body does so as well on film... Any lens adjusted to the standard will focus just great on an adjusted body--film or digital. ...The tolerances are wider on film. The tolerance for adjusting film bodies through M5 was 27.95 +0.005 mm, -0.01 mm. I would love to know if this tolerance figure has changed for more recent film/digital bodies? Of course that's not what you meant--but do have a go at it, and define "tolerances" and explain why they are wider on film... Link to post Share on other sites More sharing options...
jaapv Posted August 1, 2013 Share #9 Posted August 1, 2013 Yes - Leica narrowed the tolerance in 2007. I do not know the current values. Link to post Share on other sites More sharing options...
Jeff S Posted August 2, 2013 Share #10 Posted August 2, 2013 FWIW, Sherry Krauter works on film Ms, not digital Ms, and she told me that this was primarily due to the prohibitive cost associated with calibration equipment required in the digital realm. Jeff Link to post Share on other sites More sharing options...
120 Posted August 2, 2013 Share #11 Posted August 2, 2013 Yes - Leica narrowed the tolerance in 2007. I do not know the current values. So if I have it right, they allegedly narrowed tolerances in 2007, in 2009 along with a new test rig, and in 2012 along with the new M camera. But no one can provide any references to back this. It all seems a little dubious without a reference. Interestingly, the tolerance for the screwmount cameras in the 1930's ... 28.80 +0.015 mm, - 0.005 mm ... is essentially the same as the values for M cameras given above. In this case the distance is from flange to pressure plate, and apparently no allowance is made for the bowing / thickness of the film. Of course the screwmount standard is 1mm greater than the M standard, but we are only interested in the allowance for film. It looks like some of the forum ideas come from this 2012 posting of two emails from Leica; both have a little bit of gibberish, I think: http://www.l-camera-forum.com/leica-forum/customer-forum/219122-35-summicron-asph-sharpness-issue-continued-3.html#post1962764 Link to post Share on other sites More sharing options...
UliWer Posted August 2, 2013 Share #12 Posted August 2, 2013 Sorry, I don't understand the whole problem. Most lenses I use were made between 1932 and 1999 - i.e to be used with Leica film cameras, screw mount or M. With the exception of two of them, they all focus faultlessly on digital Ms (M8 and M9). So if it was true that the calibration was generally changed for digital bodies and that it generally differs from film bodies, all those lenses must have been out of focus for film bodies. They aren't. I have two exceptions, which don't or did not focus correctly - neither on film nor on a digital body. One has a mechanical defect. The other was "cured" by Leica customer service. They wrote "Calibration for M8/M9" on the bill, which I paid - and it now is faultless both on film and on digtial bodies. But I also have several lenses which are difficult to calibrate exactly - since they show focus shift. When I bought the M8 I had the 35mm Summilux asph coded. Afterwards I felt: something is wrong. Until I learned that this lens has rather strong focus shift. I still believe that they changed the calibration, when the coded it: exact at f/1.4, but off at f/2.8 - before it was the other way round, though I am not really sure about this, as I didn't "test" it before. So it can be that many people think, they change the whole calibration, when they only try to cope with focus shift and calibrate it for the largest aperture. Zeiss openly declares that the 1:1.5/50mm Sonnar, which also shows strong focus shift, was generally calibrated at f/2.8. They change this on demand so that it is exact at f/1.5 - but off at f/2.8. My 1.5/50 Summarit from the 50s is way off at f/1.5 but very exact at f/3.5. During film times, lenses perhaps were used differently, more practical and less to show off with their maxium. With digital usage people expect "more". So calibration, which knows about the odds and ends of the lenses follows these expectations, but it is no completely new calibration which differs from earlier times. Since the digital sensor is much less forgiving than film was, it is just very probable that they narrowed the tolerances for calibration. This cannot and it does not mean, that the focus will be off on film. Link to post Share on other sites More sharing options...
lct Posted August 2, 2013 Share #13 Posted August 2, 2013 ...The other was "cured" by Leica customer service. They wrote "Calibration for M8/M9" on the bill... Got this with an Elmarit 90/2.8 from 2003 as well, which made me wonder if calibration has changed since then. Link to post Share on other sites More sharing options...
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