wlaidlaw Posted September 3, 2007 Share #21 Posted September 3, 2007 Advertisement (gone after registration) Mark,Based on th sensitivity of the roller adjustment, do you have a feeling for the required precision for both the gauge and the micrometer for meaningful results? thanks -bob If we went for a reasonable quality digital gauge (e.g. Bowers Metrology) rather than an older mechanical, they read to 0.001mm i.e. one micron - easily accurate enough. Wilson Link to post Share on other sites More sharing options...
Advertisement Posted September 3, 2007 Posted September 3, 2007 Hi wlaidlaw, Take a look here New JLM jig for focus adjustment. I'm sure you'll find what you were looking for!
marknorton Posted September 3, 2007 Share #22 Posted September 3, 2007 I think it would need to measure no more accurately than the sensor mounting tolerance which is to the nearest 0.01mm. Link to post Share on other sites More sharing options...
1234 Posted September 3, 2007 Share #23 Posted September 3, 2007 If one believes the many assertions in other posts that a difference between 100 meters or a mile and infinity can be detected by the human eye and the M8 viewfinder, and taking into consideration the (extrapolated) slope of the curves above, would not precision much better than one micron be needed? Something doesn't jive here. Link to post Share on other sites More sharing options...
marknorton Posted September 3, 2007 Share #24 Posted September 3, 2007 My model (which I'm happy to explain in more detail) is "calibrated" to use those values of 2.1mm and 6.8mm at 0.7m and infinity. It shows that at 20m, the roller is at 6.660mm behind the lens mount; at 100m, it's at 6.768mm; at 1000 metres, it's at 6.797mm. So, in focussing from 100m to 1000m, the roller moves 0.029mm, so on that basis, I think we would need to be more accurate than +/- 0.005mm. Mitukoyo micrometer heads have an accuracy of 2 um (0.002mm). Keep in mind that 0.001mm is about 1.5 times the wavelength of light... What we don't know is what the spread of real world cameras is, just how accurately does Leica set them up and how much will they be affected by wear and temperature changes. Link to post Share on other sites More sharing options...
jrc Posted September 3, 2007 Share #25 Posted September 3, 2007 As a non-technical guy, I'd like to know why, if John can whip up one of these machines and you guys could ship it around and use it...why Leica can't do it? Why aren't all the cameras adjusted perfectly to one standard? To have each camera and set of lenses adjusted separately seems crazy. If they require you to send them your camera and all your lenses, it seems that is what they are doing... JC Link to post Share on other sites More sharing options...
wlaidlaw Posted September 3, 2007 Share #26 Posted September 3, 2007 As a non-technical guy, I'd like to know why, if John can whip up one of these machines and you guys could ship it around and use it...why Leica can't do it? Why aren't all the cameras adjusted perfectly to one standard? To have each camera and set of lenses adjusted separately seems crazy. If they require you to send them your camera and all your lenses, it seems that is what they are doing... JC Because all of us here are budding Einsteins. Wilson Link to post Share on other sites More sharing options...
Shootist Posted September 3, 2007 Share #27 Posted September 3, 2007 Advertisement (gone after registration) As a non-technical guy, I'd like to know why, if John can whip up one of these machines and you guys could ship it around and use it...why Leica can't do it? Why aren't all the cameras adjusted perfectly to one standard? To have each camera and set of lenses adjusted separately seems crazy. If they require you to send them your camera and all your lenses, it seems that is what they are doing... JC That is something I and many other on and off this forum would like to know. It just seems logical to me to have every RF set to a known standard and the lenses set to that known standard. 1 meter focusing distance is the same whether it is on a 21mm or 135mm lens, same goes for 5-10-100-1000 meters. And the roller/arm moves the same amount for those distances. Link to post Share on other sites More sharing options...
wlaidlaw Posted September 3, 2007 Share #28 Posted September 3, 2007 That is something I and many other on and off this forum would like to know.It just seems logical to me to have every RF set to a known standard and the lenses set to that known standard. 1 meter focusing distance is the same whether it is on a 21mm or 135mm lens, same goes for 5-10-100-1000 meters. And the roller/arm moves the same amount for those distances. Ed, I HOPE that we are being unnecessarily pessimistic and that Leica are not just adjusting a specific lens to an individual M8. I would like to believe that their thinking goes along the following lines: "if the customer is having difficulties with a particular lens, send both to Solms, where we shall adjust both to a standard and then finally check that when married, they still work perfectly. We can then be sure that the customer has a combination that is fully optimised." Oh well - maybe that is how it should happen in a perfect world! Wilson Link to post Share on other sites More sharing options...
colorflow Posted September 4, 2007 Share #29 Posted September 4, 2007 That is something I and many other on and off this forum would like to know.It just seems logical to me to have every RF set to a known standard and the lenses set to that known standard. 1 meter focusing distance is the same whether it is on a 21mm or 135mm lens, same goes for 5-10-100-1000 meters. And the roller/arm moves the same amount for those distances. I have a severely backfocusisng Lux 50 that was sent to NJ and came back to me without any adjustments. Upon further inquiry, NJ's answer was "the lens is within spec - it and my M8 are probably at opposite ends of allowed tolerance, so I should send both back for adjustments." This says they do have standards, but the tolerance is too loose. Leica better revise their tolerance specs! Alan Link to post Share on other sites More sharing options...
wlaidlaw Posted September 4, 2007 Share #30 Posted September 4, 2007 I have a severely backfocusisng Lux 50 that was sent to NJ and came back to me without any adjustments. Upon further inquiry, NJ's answer was "the lens is within spec - it and my M8 are probably at opposite ends of allowed tolerance, so I should send both back for adjustments." This says they do have standards, but the tolerance is too loose. Leica better revise their tolerance specs! Alan Alan, Following the last group visit to Solms, when I think it was Guy who described Leica's lens focus checking methods, projecting crosses onto screens, I thought "that is out of the dark ages". Galileo probably did that for his telescope lenses. Every other serious lens maker in the world uses a computerised high precision optical bench to verify and adjust their lenses. I did wonder, as Zeiss are the people who make these, if there was an element of Not Invented Here coming into the picture but Leica co-developed the new method of pressing asymmetrical lens blanks with Schott Glass, which is part of Zeiss. It may just be that that was good enough for Grandpa and is yet another thing Steven Lee is going to have to shake up. CZ of course use these K8 machines at Nagano for the CZ ZM lenses, which could well be why we see so few duff ones. Wilson Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/32467-new-jlm-jig-for-focus-adjustment/?do=findComment&comment=345519'>More sharing options...
colorflow Posted September 4, 2007 Share #31 Posted September 4, 2007 Alan, Following the last group visit to Solms, when I think it was Guy who described Leica's lens focus checking methods, projecting crosses onto screens, I thought "that is out of the dark ages". Galileo probably did that for his telescope lenses. Every other serious lens maker in the world uses a computerised high precision optical bench to verify and adjust their lenses. I did wonder, as Zeiss are the people who make these, if there was an element of Not Invented Here coming into the picture but Leica co-developed the new method of pressing asymmetrical lens blanks with Schott Glass, which is part of Zeiss. It may just be that that was good enough for Grandpa and is yet another thing Steven Lee is going to have to shake up. CZ of course use these K8 machines at Nagano for the CZ ZM lenses, which could well be why we see so few duff ones. Wilson Wow, I can't believe this. No wonder ... Alan Link to post Share on other sites More sharing options...
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