nscali Posted June 5, 2007 Share #1 Posted June 5, 2007 Advertisement (gone after registration) I know this has been done to death but I am just trying to understand characteristics of rangefinders and focus. I seem to have eliminated any back focus issues with all of my lenses wide open by a slight hex adjustment. What I am noticing, however, on the Noctilux and 35 lux is a slight focus shift backwards as I stop down from f2.8 - f4.0 The focus shift seems to disappear at f5.8 onwards. In other words. If a focus on a particular object (in the foreground) like a bottle, wide open, until f2 the main point of focus is where I focused on (say the label). As I stop down the label becomes a little softer (obviously the background gets more in focus). Once I hit f5.6 and onwards, the label sharpens up slightly again. Is this a normal characteristic? Are you supposed to focus slightly in front of the point of focus as you stop down? The shifts are not massive and can really only be seen at 100%. Please excuse my ignorance but I am just trying to learn. Thanks Nicky Link to post Share on other sites More sharing options...
Advertisement Posted June 5, 2007 Posted June 5, 2007 Hi nscali, Take a look here Focus Shift on Some Lenses. I'm sure you'll find what you were looking for!
carstenw Posted June 5, 2007 Share #2 Posted June 5, 2007 There have been several threads on this, and with the Noctilux and the 35 Lux Asph, many people have observed this, including myself (on a store-copy of the 35 Lux Asph). For some of these lenses the focus shift is bad enough to make the results unusable at certain apertures, unless you like guessing focus or bracketing. However, other people have lenses which do not have this problem. There is some suspicion that the chrome 35 Lux Asph may have different tolerances, and no one has had a bad one yet. Here is a link to one of the original threads, as well as the longest thread: http://www.l-camera-forum.com/leica-forum/digital-forum/17132-hair-coming-out-chunks-new-35mm.html http://www.l-camera-forum.com/leica-forum/digital-forum/17699-very-interesting-answer-leica-35mm.html Link to post Share on other sites More sharing options...
nscali Posted June 5, 2007 Author Share #3 Posted June 5, 2007 Thanks Carsten. Would I be correct in assuming that the rangefinder should be adjusted for lenses to focus correctly wide open or on stop down from wide open? I don't seem to have an issue with my 50 lux or 50 cron and and barely noticable with my 35 cron (4th Gen). Nicky Link to post Share on other sites More sharing options...
carstenw Posted June 5, 2007 Share #4 Posted June 5, 2007 The adjustment of the rangefinder is a compromise. Wide open should definitely be in focus, but there is an acceptable zone, and it should be adjusted to give the least problems with the greatest number of lenses and aperture settings, while still being sharp wide open. You could try to tweak the little wheel with a 2mm Allen key. Very small movements may find a better compromise for your 35/2 IV, while still keeping the other lenses happy. It is easy to try. Link to post Share on other sites More sharing options...
tashley Posted June 5, 2007 Share #5 Posted June 5, 2007 The adjustment of the rangefinder is a compromise. Wide open should definitely be in focus, but there is an acceptable zone, and it should be adjusted to give the least problems with the greatest number of lenses and aperture settings, while still being sharp wide open. You could try to tweak the little wheel with a 2mm Allen key. Very small movements may find a better compromise for your 35/2 IV, while still keeping the other lenses happy. It is easy to try. But let's not forget that the degree of focus shift is not even across the field. In my experience we tend to give most attention to viewing the centre portion of an image but if you were to look at your shots really carefully you would probably see that the F2 thru 5.6 images show the point on which you focussed (if in the centre of the field) has gone out of focus but the edges remain sharp. This is related to the fact that the shift is caused by the aspherical construction of the lens. Best Tim Link to post Share on other sites More sharing options...
jonoslack Posted June 5, 2007 Share #6 Posted June 5, 2007 Hi There I hadn't read the suggestion about chrome lenses being different; is this really the case? Personally I've rather fallen in love with the chrome lens on black body look Link to post Share on other sites More sharing options...
tashley Posted June 5, 2007 Share #7 Posted June 5, 2007 Advertisement (gone after registration) Hi There I hadn't read the suggestion about chrome lenses being different; is this really the case? Personally I've rather fallen in love with the chrome lens on black body look It was only an idle suggestion that came up in the early days of the puzzle, because Jamie was the first person to report a 'perfect' 35 lux and his was chrome. But I think there _may_ be more likely an issue with lenses with more recent serial numbers and some have theorised that it is to do with the coded mounts. You were to be the test case... :-( t Link to post Share on other sites More sharing options...
jonoslack Posted June 5, 2007 Share #8 Posted June 5, 2007 It was only an idle suggestion that came up in the early days of the puzzle, because Jamie was the first person to report a 'perfect' 35 lux and his was chrome. But I think there _may_ be more likely an issue with lenses with more recent serial numbers and some have theorised that it is to do with the coded mounts. You were to be the test case... :-( t Of course - it seems to me that if you want an aspherical 35mm leica lens you are doooooomed - there is no escape. Either it's useless, or it's stolen. One thing you can be sure of is that my lens was, in fact, absolutely perfect - maybe the guy from the Isle of Dogs who will get it back posts around here? Then he can be the guinea pig! Link to post Share on other sites More sharing options...
Eoin Posted June 5, 2007 Share #9 Posted June 5, 2007 Jono, It is just an observation that those of us with chrome 35 Summilux Asph lenses (uncoded I might add) seem not to have this reported back focus issue. One must remember that the Chrome 35's were from a different era while most of the backfocus seem to be from current (later stock or lenses which were returned for coding) batch. I can't see why this is the case, other than current lenses may have some issues with QC. Who knows, it's all pure speculation. However my chrome 35 Lux Asph is spot on except for when I make an error. Link to post Share on other sites More sharing options...
jonoslack Posted June 5, 2007 Share #10 Posted June 5, 2007 Jono, It is just an observation that those of us with chrome 35 Summilux Asph lenses (uncoded I might add) seem not to have this reported back focus issue. One must remember that the Chrome 35's were from a different era while most of the backfocus seem to be from current (later stock or lenses which were returned for coding) batch. I can't see why this is the case, other than current lenses may have some issues with QC. Who knows, it's all pure speculation. However my chrome 35 Lux Asph is spot on except for when I make an error. There is a thief about. I'm surprised you even admit having such a thing to me (now a known criminal). Just have a look in your camera bag, and you'll find it's gone (transferred using my new matter transferance device). You don't want to sell it do you? Thanks for your sympathy on the other thread - I did think I was going to answer everyone, but it quickly became impractical! Link to post Share on other sites More sharing options...
Eoin Posted June 5, 2007 Share #11 Posted June 5, 2007 Ah well! brothers in Apertures arms and all that, I didn't feel I would be at risk from your sticky fingers LOL. Funny you should ask about selling it, I'm seriously considering my lens line up. I'm just waiting (2 more weeks) for my Noctilux and then I'll decide if I'll keep my current 21Asph(chrome) 35Asph(chrome) & 75Asph or just bite the bullet and sell all 3 and get a 28 Summicron Asph to go with the Nocti and Summicron 50s. This all depends on the Nocti and how I like it for portrait type stuff. I know you love the 75AA, I just can't get comfortable with it's fingerprint. Fantastic lens and all but, oh! how I miss the fingerprint of my 85L. Link to post Share on other sites More sharing options...
tashley Posted June 5, 2007 Share #12 Posted June 5, 2007 Ah well! brothers in Apertures arms and all that, I didn't feel I would be at risk from your sticky fingers LOL. Funny you should ask about selling it, I'm seriously considering my lens line up. I'm just waiting (2 more weeks) for my Noctilux and then I'll decide if I'll keep my current 21Asph(chrome) 35Asph(chrome) & 75Asph or just bite the bullet and sell all 3 and get a 28 Summicron Asph to go with the Nocti and Summicron 50s. This all depends on the Nocti and how I like it for portrait type stuff. I know you love the 75AA, I just can't get comfortable with it's fingerprint. Fantastic lens and all but, oh! how I miss the fingerprint of my 85L. Buddy, you don't want to hear this but my brand new 28 cron had chronic focus issues, much worse than any of the 35s I had, and has been returned. The replacement is arriving on Friday and I'm getting together with William Laidlaw to try it on his M8 as well as mine. If it too is a loser, then I'll jest have to get the 28 elmarit. My other M8 is in Solms with my 35 Cron at the moment too, they are being slowly reintroduced to each other in the wild to see if they'll get on... Best T Link to post Share on other sites More sharing options...
Eoin Posted June 5, 2007 Share #13 Posted June 5, 2007 Well balls to that!, you've been through the mill on this Tim, I bet your questioning your own eyesight, LOL. Re-introducing the 35 & M8 back in the wilds of solms will I hope result in a within spec offspring and I'm sure we won't get the lowdown on copulation method used. It will be interesting to see how my new Nocti preforms with regard to focus given that I have no real issues with any of my lenses, fingers crossed. Link to post Share on other sites More sharing options...
tashley Posted June 5, 2007 Share #14 Posted June 5, 2007 Well balls to that!, you've been through the mill on this Tim, I bet your questioning your own eyesight, LOL. Re-introducing the 35 & M8 back in the wilds of solms will I hope result in a within spec offspring and I'm sure we won't get the lowdown on copulation method used. It will be interesting to see how my new Nocti preforms with regard to focus given that I have no real issues with any of my lenses, fingers crossed. LOL - I'll spare you the gory details! I tried a friend's nocti in a restaurant for a few shots and it seemed to have absolutely precise focus. But it was uncoded, and WIlliam's was worse after being coded... There is a consistent story here itching to get out, but none of us can quite put our fingers on it. :-( t Link to post Share on other sites More sharing options...
erl Posted June 5, 2007 Share #15 Posted June 5, 2007 To offer a little hope to 'wannabe' Nocti oficianos, mine was terrible on the M8. Never noticed a problem on the M7 though! The Noct went to Solms for checking, and coding and returned perfect as far as I am now aware. I have not done measured tests, but have used it for work under extreme conditions and it passed with flying colours as far as I am concerned. So I say, Trust the Gnomes at Solms!. Link to post Share on other sites More sharing options...
pemayeux Posted June 5, 2007 Share #16 Posted June 5, 2007 I have a black 35/1.4 ASPH and it's focus is absolutely perfect from 1.4 to 8 (the smallest stop I have ever used). Of all my lenses, it is my favorite on both film and digital. I have 28/2.8 ASPH, TriElmar, Nocitlux, 50/1.4 ASPH and 75/1.4. The only lenses that I had focus problems with on the M8 was the 50 and the 75, both of which are in Solms for repair. Both had focus shift problems. The 50 is being fixed under warranty and the 75 needed an adjustment. Link to post Share on other sites More sharing options...
Eoin Posted June 5, 2007 Share #17 Posted June 5, 2007 ...... So I say, Trust the Gnomes at Solms!. I hope so Erl, if my 30% Nocti shows any sign of miss focus I'll be singing Hi ho, hi ho it's back to shagging Solms you go!. Link to post Share on other sites More sharing options...
carstenw Posted June 5, 2007 Share #18 Posted June 5, 2007 I got my 28 Cron yesterday, and tested it right in the store. It is perfectly sharp wide open, ever so slightly less sharp at f/4 and perfect at all other apertures. For my uses, it is well within tolerance, and I was very relieved. Link to post Share on other sites More sharing options...
jsjxyz Posted June 5, 2007 Share #19 Posted June 5, 2007 This might be my WILD guess: Actually the problems are mostly on our lenses not on M8... We never realize the problem with our lenses because when we use film, we never create a big print or use loop to check. Why don't you before sending both the M8 and the lenses, try to fix/calibrate the lenses with local Leica technition, without even think of giving your M8. See the results. It happend with my 75 Lux. Jerry Link to post Share on other sites More sharing options...
jonoslack Posted June 5, 2007 Share #20 Posted June 5, 2007 Jono, It is just an observation that those of us with chrome 35 Summilux Asph lenses (uncoded I might add) seem not to have this reported back focus issue. One must remember that the Chrome 35's were from a different era while most of the backfocus seem to be from current (later stock or lenses which were returned for coding) batch. Well, I will be the proud owner of a Chrome 35 'cron tomorrow - it's 6 bit coded (says so on the box too). I ordered from Robert White as they can get it to me for tomorrow. I must say, I wasn't aware that they were still making them. It's recent stock for them, but has a 39 serial number. It'll be interesting to see how it performs! Link to post Share on other sites More sharing options...
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