myshkine Posted July 17, 2011 Share #1 Posted July 17, 2011 Advertisement (gone after registration) Ok, it has been already discussed in other threads. But browsing through Alessandro Pasi's book "Leica, witness to a century", I learned that some old Leicas, notably the IIId and the 250 Reporter, had a diopter adjustment mechanism. The diopter corrections lenses cost a lot. I recently lost mine and I know how easy it is for them to unscrew from the eyepiece. Is anyone aware of technical issues that would make it impossible for Solms to replicate it on current models and have a built-in adjustment in the VF? Cheers. Quote Link to post Share on other sites More sharing options...
Advertisement Posted July 17, 2011 Posted July 17, 2011 Hi myshkine, Take a look here Diopter adjustment in old Leicas. I'm sure you'll find what you were looking for!
StephenPatterson Posted July 17, 2011 Share #2 Posted July 17, 2011 All the screw mount Leica bodies with rangefinders from the III to the IIIG had a diopter adjustment, mainly I believe because the viewfinder was so small as to preclude it's use while wearing glasses. When the M3 was introduced the viewfinder was substantially increased in size to allow for framing and focusing while wearing glasses, and the built in diopter adjustment was discontinued. It's probably not possible to know the reasons why this decision was made in 1952-1953 when the M3 was in development. No doubt cost and size were factors. Quote Link to post Share on other sites More sharing options...
jaapv Posted July 17, 2011 Share #3 Posted July 17, 2011 No - it was not a diopter adjustment. The RF could be focussed from about 1.5 m to infinity, the viewfinder was a fixed telescope. Quote Link to post Share on other sites More sharing options...
StephenPatterson Posted July 17, 2011 Share #4 Posted July 17, 2011 Yes, Jaap is correct that the diopter adjustment was only used to correct for individual user's vision on the rangefinder window of screw mount Leica cameras. The viewfinder has never had diopter correction built into the camera body. 1 Quote Link to post Share on other sites More sharing options...
jaapv Posted July 17, 2011 Share #5 Posted July 17, 2011 It is not for vision - it is for distance. There is even an infinity mark engraved on the body. 1 Quote Link to post Share on other sites More sharing options...
myshkine Posted July 17, 2011 Author Share #6 Posted July 17, 2011 Thanks to all. I understand that we are not going to have an M camera with diopter adjustment anytime soon... Quote Link to post Share on other sites More sharing options...
StephenPatterson Posted July 17, 2011 Share #7 Posted July 17, 2011 Advertisement (gone after registration) It is not for vision - it is for distance. There is even an infinity mark engraved on the body. Not sure I agree with you on this one. From my personal experience with my IIIC I set the diopter about in the middle of the scale to adjust for my vision. This works for me at close and very far distances. From Alessandro Pasi's book "Leica, witness to a century", which the OP referenced, on page 49 describing the 250 Reporter, "Diopter adjustment - Near the rear eyepiece of the viewfinder is a lever to adjust the vision for those with vision defects". And from Dennis Laney's "The Leica Collector's Guide, 2nd Edition" on page 70 under Characteristics describing the Leica III, Model F introduced in 1933, "Eyesight diopter correction provided by small lever rotating round the eyepiece". Quote Link to post Share on other sites More sharing options...
jaapv Posted July 17, 2011 Share #8 Posted July 17, 2011 OK. What do you think an arrow and infinity mark mean? 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! Quote 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/157136-diopter-adjustment-in-old-leicas/?do=findComment&comment=1737387'>More sharing options...
StephenPatterson Posted July 17, 2011 Share #9 Posted July 17, 2011 You're probably right Jaap, and I cannot explain Leica's use of the infinity logo, but from my personal experience and the books I have read this adjustment seems to be to correct for differences in vision, and not as a focus mechanism. From my personal experience, having 20/20 vision, I set the lever in the middle and do not change it for viewing, regardless of the distance to the subject. This seems to be to be the very definition of diopter correction, but you could very well be correct. Quote Link to post Share on other sites More sharing options...
jaapv Posted July 17, 2011 Share #10 Posted July 17, 2011 Handbooks are like parrots. Once an assertion is made it will be repeated ad infinitum. Obviously a distance adjustment will, in part, make do as an eyesight correction. But that was imo not the intention of the Leitz designers. I wonder, could an owner of an LTM camera manual have a look what the users instrictions have to say about it? Quote Link to post Share on other sites More sharing options...
luigi bertolotti Posted July 17, 2011 Share #11 Posted July 17, 2011 (edited) Jaap is right : the IIIc manual is very clear about : A) Adjustment of rangefinder telescope : "... by means of the small lever it may be focused on distant objects. The telescope also compensates for slight eyesight defects (from - 2 to +1,5 diopters)" (another page on VF/RF) Important for those with defective eyesight : "correction lenses to suit the user's sight can be fitted to the twin eyepiece....the correction lenses are prepared to the user's optician's prescription". The IIIa manual does not mention correction lenses; the IIIG manual says exactly the A) and points above, but details that the focusing lever compensates for defects from -4 to +2 diopters The correction lenses are regularly listed in many pricelists of LTMs, always detailing to send the prescription with the order of them. Edited July 17, 2011 by luigi bertolotti 2 Quote Link to post Share on other sites More sharing options...
giordano Posted July 17, 2011 Share #12 Posted July 17, 2011 It's just like binoculars, where the focus adjustment depends on both object distance and the user's eyesight. But the magnification is so low that most peoples' eyes have enough accommodation (focusing range) to cope with most focusing distances without noticing, so the lever seems to be simply a dioptre correction. And that's what I thought it was when I got my first Leica in 1969. Nowadays I've learnt better: I need to tweak the little lever between distant and close subjects - or look through a different part of my varifocal glasses. Quote Link to post Share on other sites More sharing options...
pico Posted July 18, 2011 Share #13 Posted July 18, 2011 All the screw mount Leica bodies with rangefinders from the III to the IIIG had a diopter adjustment, mainly I believe because the viewfinder was so small as to preclude it's use while wearing glasses. When the M3 was introduced the viewfinder was substantially increased in size to allow for framing and focusing while wearing glasses, and the built in diopter adjustment was discontinued. It's probably not possible to know the reasons why this decision was made in 1952-1953 when the M3 was in development. No doubt cost and size were factors. Perhaps that was the rationale, but in 2011 many, many of us could use the variable diopter. Leica should bring it back. Heck, cheap digital cameras have it as standard and it is helpful. What makes Leica thinks it is exempt? 1 Quote Link to post Share on other sites More sharing options...
StephenPatterson Posted July 18, 2011 Share #14 Posted July 18, 2011 Jaap, Luigi, Giordano & Pico, thank you for the information. I'm learning every day Stephen Quote Link to post Share on other sites More sharing options...
giordano Posted July 18, 2011 Share #15 Posted July 18, 2011 (edited) When the M3 was introduced the viewfinder was substantially increased in size to allow for framing and focusing while wearing glasses, I'm certain that wasn't the main reason. Rather, increasing the magnification and field of view from c. 0.5 and 50mm equivalent (in the IIIf) to the M3's c. 0.9 and 40mm equivalent made it essential to increase the size of the eyepiece and the eye relief. And the eye relief on the M finders isn't really good enough for spectacle-wearers. There's no sign that Leitz really took that seriously, certainly not the way Zeiss did only a few years later with their -B (for Brillen?) suffixed binoculars. I'm not 100% sure of this next bit, but ISTM that with the extremely low power of the M3 eyepiece lens, providing "dioptric" compensation in the same way as on the IIIf would have involved moving the eyepiece large distances backwards or forwards. Quite apart from any physical physical constraints, this would have altered the field of view through the finder window. I haven't worked out whether it would also affect the relationship between the finder window, the framelines and the rangefinder patch. The same argument would apply, somewhat less strongly to later bodies with magnifications in the 0.58 to 0.85 range. So the only neat way to adjust for eyesight was with the little supplementary lenses we know and loathe. Maybe the M10 will come with a variable-curvature plastic eyepiece lens! Edited July 18, 2011 by giordano Waste clearance Quote Link to post Share on other sites More sharing options...
myshkine Posted July 18, 2011 Author Share #16 Posted July 18, 2011 I certainly do not have the technical expertise of most of the members that have commented here, but as Pico has said, what prevents today Leica from inserting a built in diopter correction? Is there any limitation in the construction of the viewfinder or something else?I used to have a cheap (relatively to my current M6) Olympus E 410, and it had a very effective diopter adjustment knob. Quote Link to post Share on other sites More sharing options...
luigi bertolotti Posted July 18, 2011 Share #17 Posted July 18, 2011 (edited) I certainly do not have the technical expertise of most of the members that have commented here, but as Pico has said, what prevents today Leica from inserting a built in diopter correction? Is there any limitation in the construction of the viewfinder or something else?I used to have a cheap (relatively to my current M6) Olympus E 410, and it had a very effective diopter adjustment knob. Without going too deep, there is much difference when one has to look at an image that "stays" on a ground glass (SLR) from when one looks through a telescope , that is a viewfinder like Leica's one: they are very different optical systems: in the first one, the eye must see at a fixed distance (the optical course through the pentaprism), in the other, the eye must see at very varying distances: is easier to correct a defective sight at a fixed distance. To make a "Leica" example, the vertical finder for the Visoflex has a very simple and effective diopter correction... it is a SLR-type finder. Edited July 18, 2011 by luigi bertolotti Quote Link to post Share on other sites More sharing options...
jc_braconi Posted July 19, 2011 Share #18 Posted July 19, 2011 Diopter adjustment in old Leicas was with the ORTUX and some others code words with correction for near or long sight and also astigmatism, have a look at page 19 of Dennis Laney Accessory booklet. Quote Link to post Share on other sites More sharing options...
Guest Ron (Netherlands) Posted July 21, 2011 Share #19 Posted July 21, 2011 Before introducing the M3 Leitz surely must have examined or at least have known about the Zorki 3 rangefinder camera which was introduced in 1951 and already had a combined range- and viewfinder, a clear VF of c 1.0 combined with diopter correction. What the Zorki lacked were built-in framelines. Leitz clearly choose not to build in a diopter correction, but instead preferred to work with separate screw-in diopters. Quote Link to post Share on other sites More sharing options...
giordano Posted July 21, 2011 Share #20 Posted July 21, 2011 Thanks, Ron. Do you know of a schematic diagram or detailed photographs of the Zorki 3 range/viewfinder anywhere on the internet? Quote Link to post Share on other sites More sharing options...
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