ho_co Posted April 20, 2007 Share #61 Posted April 20, 2007 Advertisement (gone after registration) Tim--No question, you have a problem with the 28; clearly it is too far forward in its mount; and when you can spare it, I would also send the 'tweaked' M8 for rangefinder checkup Jamie--The argument you cite from EP invokes the "film is thicker" condition which you reject--logically, you cannot accept the conclusion of his argument if you reject the premise IMHO you will eventually have to join us in the 'thicker and not plane' brigade Peter--Superb summary Guy--As Tim said, excellent pragmatic solution, avoiding all the theoretical issues and getting down to parameters of use Charles--As Jamie said, a properly adjusted lens will work on both film and digital bodies --your comment "Don Goldberg, who is not a repairman unfamiliar with Leicas (ha!) ..." may aim at something you think I said: I didn't say that no one but Leica should work on a Leica product; I said to be sure that the person who works on your camera or lens knows her/his way about it: My suggestion is to send the lens to Leica and only to Leica. Others would say to send it to a recognized competent lens repair technician, and I won't argue with that so long as the repair agency is familiar with Leica's designs. Point of clarification: 'Optical infinity' is different from rangefinder infinity. A designer computes a lens for "infinity," usually but not always 1000x focal length, because the computations are simpler. Upshot: each different focal length has its own "infinity." The rangefinder mechanism, on the other hand has a single infinity point which doesn't change with different lenses. Therefore comparing performance by testing a 75mm at 75m and a 16mm at 16m on a camera is unnecessary. For all lenses, the rangefinder will show infinity at the same distance. --HC Link to post Share on other sites More sharing options...
Advertisement Posted April 20, 2007 Posted April 20, 2007 Hi ho_co, Take a look here Backfocus and Focus Shift: The Plot Thickens. I'm sure you'll find what you were looking for!
Jamie Roberts Posted April 20, 2007 Share #62 Posted April 20, 2007 {snipped}Jamie--The argument you cite from EP invokes the "film is thicker" condition which you reject--logically, you cannot accept the conclusion of his argument if you reject the premise Eventually you will have to join us in the 'thicker and not plane' brigade {snipped} Howard, Never! What I accept is that the M8 is built to higher tolerances, which is pretty easy to measure. Whether those higher tolerances are necessary because the film emulsion was "thicker" than the sensor, or because film focus wasn't as critical due to its analog nature, or because the sensor and microlens array has special needs for critical focus, or because the moon was full when they designed it, I really have no idea. All I know is that practically there is no difference in shooting. Link to post Share on other sites More sharing options...
newyorkone Posted April 20, 2007 Share #63 Posted April 20, 2007 No, I think they're mostly a red herring. For example, if what Peter says is true, I have 1) A magic camera 2) A magic set of lenses 3) and a very Magic Noctilux, where I shot 4GB of test shots on the M8 with a Noctilux from f1.0 to f5.6 . They were all in focus at the focus point. IOW, the lens did not go "out of focus" by f2. Since I don't believe in magic, but I do believe in internet nonsense, I've made my own conclusions Congrats Jamie. You have quite the luck. Was everything spot on right out of the box or did you send the camera and lenses off to Leica for tweaking? Link to post Share on other sites More sharing options...
charlesphoto99 Posted April 20, 2007 Share #64 Posted April 20, 2007 Hi All, Well, I popped into my dealer and the 28 Summ showed the same behavior on their floor model as on mine. Same as Tim - when nudged to between the infinity marking and the 10M mark it snaps into focus but really blurry racked all the way to infinity. Lens is off to Leica as we speak, and I'll have it coded at same time. Think the body might go off today as well and it's back to the M7 and/or medium format for a bit. Link to post Share on other sites More sharing options...
jonoslack Posted April 20, 2007 Share #65 Posted April 20, 2007 The one thing I would add is that I have bought a lot of brand new glass. I wonder if that is one of the variables to consider?! All the best Tim Hi Tim I've read all this with interest - really! I think that you're right, and these things better be got right with a lens. My 90 f4 macro seemed to backfocus - rather than testing it to distruction I sent it to Leica UK - they confirmed that it was really out - checked stock - found that their one stock lens was also out, and sent it back to Solms - boring, but I wasn't going to sort it out. Maybe the answer to these issues is twofold: 1. Like most manufacturers, Leica's lenses vary a lot 2. If you got a problem - send it back to them (boring though it is). Personally, all the 'film thickness' and other esoteric arguments seem unnecessarily complicated. As far as I can see, with film nobody really noticed these differences, because there was neither instant feedback, nor 100% viewing. Anyway - good luck mate! Link to post Share on other sites More sharing options...
Jamie Roberts Posted April 20, 2007 Share #66 Posted April 20, 2007 Steve-- When my M8 returned from Leica, because it had a broken selector wheel problem, and so they switched out the body entirely. When I got it back, it backfocussed completely consistently, and just the way Brad described it. It was, however, the same across all my lenses--by 2.5 inches. I spent 2 solid days tweaking the infinity adjustment (yes, the hex fix!) to get them to the point where they were sharp wide open and at infinity, through the aperture range. (Jono--thanks for saying what I've been trying to say much more succinctly ) Link to post Share on other sites More sharing options...
tashley Posted April 20, 2007 Author Share #67 Posted April 20, 2007 Advertisement (gone after registration) Thanks Jono! I have to say that there seem to be a number of people posting here who have seen the same behaviour. I would bet the soul of my firstborn that neither of my RF is significantly out. So there are a lot of error prone lenses out there for whatever reason. Bart is giving me an exchange for new on this lens, and if I can't get a good one soon I'll end up getting a 28/35/50 cos I tried yours and I KNOW it focusses! Best as ever T Link to post Share on other sites More sharing options...
ho_co Posted April 20, 2007 Share #68 Posted April 20, 2007 Oh, lord! Just when I thought we were making headway with the "film is thicker than sensors" argument we start getting the "No, really! It *does* backfocus! Leica wil fix it!" argument. Now that's just not fair. Here we are, honing our rhetorical skills, stretching points only slightly, explaining that these are Leica products built to incredibly tight tolerances and that only quantum mechanics can explain what's happening--and suddenly someone says, "Hey, wait a minute! It left the factory that way! And they can fix it!" But I remind you whippersnappers: That covers only a few products. We of warped mind still stand, unimpressed by negligible fact. We defend against all indulgence in over-simplicitude. Send in Occam and we'll chop him down to size with his own shaver (currently a 3-head rotary model if I'm not mistaken)! 'Zounds! Where is Zeno when you need him? Or Procrustes? --HC Link to post Share on other sites More sharing options...
john_nyc Posted April 20, 2007 Share #69 Posted April 20, 2007 It looks like I'm having the same backfocus problem with my new 28 'cron, also. My other lenses seem to be dead-on so I'm reluctant to attempt any adjustment to the M8's RF. Link to post Share on other sites More sharing options...
charlesphoto99 Posted April 20, 2007 Share #70 Posted April 20, 2007 It looks like I'm having the same backfocus problem with my new 28 'cron, also. My other lenses seem to be dead-on so I'm reluctant to attempt any adjustment to the M8's RF. Actually, what Tim and are having is technically more of a "frontfocusing" problem; ie the plane of focus is in front of what it should really be according to the rangefinder. A lens should be spot on at infin ity no matter what the rangefinder patch is telling you. If it isn't, then it's the lens. Just got M8 off to Leica (28 went seperately through my dealer hoping it will be covered by previous repair warranty). I think all new M8's should come with two prepaid Fed Ex vouchers! If you don't use them for the body, you sure as heck will for the lenses (even if to just get coded). Link to post Share on other sites More sharing options...
jonoslack Posted April 20, 2007 Share #71 Posted April 20, 2007 Oh, lord! Send in Occam and we'll chop him down to size with his own shaver (currently a 3-head rotary model if I'm not mistaken)! --HC LOL you must be psychic - I promise you, I was considering mentioning our William, and then thought that it wasn't necessary. Clearly it wasn't, but I'm gratified that I got my point across! Link to post Share on other sites More sharing options...
kaimaui Posted April 20, 2007 Share #72 Posted April 20, 2007 35mm summilux. I am just about to order this lens with my 30% off and am wondering if there is a inherent problem with focus shift at different apertures. Or is it simple a matter of some lenses being off. Of course in practical use not theory. Link to post Share on other sites More sharing options...
jonoslack Posted April 20, 2007 Share #73 Posted April 20, 2007 Thanks Jono! Bart is giving me an exchange for new on this lens, and if I can't get a good one soon I'll end up getting a 28/35/50 cos I tried yours and I KNOW it focusses! Best as ever T But knowing your luck (or is it your dedication) you'd get one which didn't focus! Hope you're well, we're off to Greece on Sunday (so I'm told) Link to post Share on other sites More sharing options...
tashley Posted April 20, 2007 Author Share #74 Posted April 20, 2007 But knowing your luck (or is it your dedication) you'd get one which didn't focus!Hope you're well, we're off to Greece on Sunday (so I'm told) LOL... I've been thinking about this and you know, I think it IS luck in an odd sort of way... it's a long argument but... The M8 can achieve some truly extraordinary stuff and, like all truly fab gear, it is temperamental. So to get the best out of it you have to be really alert and willing to be be precisely critical. You learn to sort the wheat from the chaff, gear wise, and you end up with a killer bag that gives results that technically few people will get, just cos you were nerdy at times. And that slooooowly gives you an advantage. Then you realise that all of that is secondary to the ability to see the world interestingly and that THAT is the thing you should have given more attention to... Back to the drawing board! We march on. Have a great time in Greece, and post lovely blue and white for the rest of us. best t Link to post Share on other sites More sharing options...
AH6061 Posted April 20, 2007 Share #75 Posted April 20, 2007 It is my humble belief that the glass cover on the sensor, which corrects lens distortion, may be at fault. Link to post Share on other sites More sharing options...
newyorkone Posted April 21, 2007 Share #76 Posted April 21, 2007 Steve-- When my M8 returned from Leica, because it had a broken selector wheel problem, and so they switched out the body entirely. When I got it back, it backfocussed completely consistently, and just the way Brad described it. It was, however, the same across all my lenses--by 2.5 inches. I spent 2 solid days tweaking the infinity adjustment (yes, the hex fix!) to get them to the point where they were sharp wide open and at infinity, through the aperture range. Thanks. I would be very grateful for any insight you might have from your 2 days of tweaking. When I tried the "hex" fix, things didn't go as expected at first because from all the threads that I had read, I thought turning clockwise would do the trick for backfocus. I started out making very small adjustments but then the focus got worse and worse. This freaked me out and then I adjusted counter-clockwise and got things to a point where it was better but still not perfect. But the next morning I discovered that the counter-clockwise adjustments had thrown off the infinity focus point. At that point I pretty much gave up and now I just compensate in the RF but it is annoying because my M6 always focused perfectly. I've resigned to the fact that I'm probably going to just have to bite the bullet and cart the whole lot off to Leica NJ. All my lenses backfocused in a predictable way like yours but it was more noticeable with the Noct so I'm hoping that I might be able to duplicate your results and avoid having to be without the M8 which I am finding to be indispensable. Thanks again. Link to post Share on other sites More sharing options...
bradreiman Posted April 21, 2007 Share #77 Posted April 21, 2007 It is my humble belief that the glass cover on the sensor, which corrects lens distortion, may be at fault. welcome to the forum and....HA!! My m8 focusses perfectly on all 8 of my lenses, how might you explain this sir? and i mean razor sharp with a noctilux at f1 from 1 meter to infinity and corresponding view in rangefinder overlapping at all stages.....b Link to post Share on other sites More sharing options...
thpeters Posted April 21, 2007 Share #78 Posted April 21, 2007 HA!! My m8 focusses perfectly on all 8 of my lenses Bradley, It must be that you live downunder, closed to the south pole, stronger magnet field maybe that fix it, the rest in the world people with leica's have problems with back and front focus. LOL. Theo Link to post Share on other sites More sharing options...
tashley Posted April 21, 2007 Author Share #79 Posted April 21, 2007 HA!! My m8 focusses perfectly on all 8 of my lenses, how might you explain this sir? and i mean razor sharp with a noctilux at f1 from 1 meter to infinity and corresponding view in rangefinder overlapping at all stages.....b Oh shush, now you're just taunting us! ;-) t Link to post Share on other sites More sharing options...
AH6061 Posted April 21, 2007 Share #80 Posted April 21, 2007 welcome to the forum and....HA!! My m8 focusses perfectly on all 8 of my lenses, how might you explain this sir? and i mean razor sharp with a noctilux at f1 from 1 meter to infinity and corresponding view in rangefinder overlapping at all stages.....b As per your request: an elaboration. Perhaps one should not describe the [negative] situation as being entirely reliant on one system. Moreover, I believe it is the interaction between this filter and the sensor, possibly when misaligned, that causes the problem. Furthermore, I believe there is some merit to the "Flat-Plane vs Film" theory. I own, as you do, a "perfectly" focusing M8 when used with many if not all lenses. (At least I hope so! ) Do you have a better theory? (I take it not to be so...) The best course of action, as far as I am concerned, is to either reverse engineer the M8 system by system, or somehow retrieve the specifications for the system(s) affected from Leica. With this data, as well as some experimentation, my colleagues and I will most likely be able to isolate the problem and possibly engineer a method of fixing it. Edit: By the way, my colleagues are a myriad of both very happy and very angry Leica owners. Link to post Share on other sites More sharing options...
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