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So... about backfocus...


jaa

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I got my M8 last Tuesday. Black, 3195xxx. Being a M7 user, I felt right at home. I don't particularly like the extra thickness and the shutter noise but it's no big deal. Picture quality seems fantastic (I use "seems" only because I'm still experimenting). I was as happy as I could be when I noticed the infamous backfocus (on a series of portraits where the eyes were not sharp but the temples were.

 

I have a 28 Elmarit Asph, a 35 'cron Asph (away for coding), and a 50 'lux Asph. The 50 backfocuses terribly at all distances (at about 5 m it backfocuses at least 30 cm) and it doesn't reach infinity (I assume it focuses on infinity but the focusing ring reaches the end of its curse when focusing on anything maybe 100 m away and the two images in the viewfinder never superimpose completely).

 

The problem seems to be there as well when the lens is on a M7 (which could explain a few things about some of my past photos...) although maybe not on the same scale.

 

Apparently, the 28 Elmarit focus a lot better, even if I'm not sure it's perfect.

 

To illustrate the problem (and we like to see photos, even when they’re nothing special, don’t we?), I include two photos (whole plus 100 % detail). First: 50 ‘lux. Second: 28 Elmarit. Both focused at about 0,8 m, on the word "misleading". I made several attempts and the results were similar.

 

Now for my questions:

 

1. Is this reason to demand a camera replacement and would Leica accept it? (I have no real desire to do it but…)

 

2. As it seems that the majority of the problem lies with the 50 ‘lux and I have yet to send it for coding (I wasn’t really planning to code it but… oh, well), could Leica adjust it without the camera?

 

Any answers / suggestions will be appreciated. Thanks.

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Welcome to the forum. If the lens is a bit off on the M7 it seems to be clear. The M8 shows these faults up mercilessly. You'll have to send it in for shimming...

 

Thanks (for the welcome and the answer). In the meanwhile, I found this thread:

 

http://www.l-camera-forum.com/leica-forum/leica-m8-forum/13933-new-backfocus-thread-solution.html

 

but I'm not going to start playing with a wrench before the lens is adjusted...

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First does the camer focus to infinity with the 28mm? the only real way to check that is to focus on a star at night and the images should line up in the VF. If they don't then you have a infinity focus problem and that can be corrected by adjusting the wheel.

If it does then the problem you are having with the 50mm is the lens NOT the camera.

You say it does the same on your M7. Well then it is the lens that needs adjusting.

 

the only way to check close focus is after you have the RF/VF adjusted properly for the infinty setting WITH a LENS YOU KNOW to be GOOD/CORRECT.

 

I know my 50 Cron is right on because I have used it on 4 different M8 bodies and on 3 of them it was spot on. On the 4th body it backfocused slightly. Checking that body for infinty focus with the 50mm Cron showed the @ infinity setting on the lens the images in the VF where going to far, IE past each other. I made the wheel adjustment and now that camera focuses correctly at closer distances.

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First does the camer focus to infinity with the 28mm? the only real way to check that is to focus on a star at night and the images should line up in the VF.

 

Just to annoy me, the sky has been cloudy around here... and there's even quite a bit of fog. :) But the two viewfinder images seem to superimpose nicely on the 28 with subjects a few hundred metres away, which doesn't happen with the 50 (the lens ring reaches the end of its course way before that).

 

I don't want to send the camera away so I do hope it's (just) the lens. Even when I'm going to miss it as well and wonder every day if it's alright (like I do now with the 35 'cron; I'm way too overprotective with my cameras and lenses...)

 

This isn't the photo forum but here's one of the first photos I took with the M8 and the 50 'lux:

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Infinity focus is never exactly that, of course – not even a star is at literally infinite distance! The universe is not infinite, only pretty big. In optical practice, infinity is reckoned to be at 1000 x the focal length, i.e. 28m for a 28mm lens and 50m for the 50 ... a distant lamppost will be enough.

 

Also, the 50mm Summilux ASPH, because of its floating elements, is not subject to any real amount of aperture error (focus shift on stopping down). So if this too backfocuses, something pretty drastic has to be afoot. And (please do not take this as a slur) not always with the lenses or the body.

 

The old man from the Age of Scale Focusing

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Jose',

 

Wellcome to the forum. I seem to have the same problem as you. My 50 mm 1,0 Noctilux backfocuses with about 10 cm at 2 meters distance. It looks alright - through the viewfinder, at infinity, - and so does all the other lenes I have. None of my other lenses seem to backfocus: A guy here told me that every noctilux have to be adjusted to each and every individual camera. I have had my Noctilux for coding at Solms and hoped that this would help. It did not. It seems to that I have to bring both the camera and the Nochtilux to the Norwegian Leica importer.

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my 50 lux asph also backfocuses, you have to send it back to Solm for adjustment, coding is not necessary for 50mm or above, unless you want to tip them, but I think coding should be thrown in for free, i just guess Leica flopped up when making this their first floating element lens. but this the best of their 50s i have used.

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Thanks (for the welcome and the answer). In the meanwhile, I found this thread:

 

http://www.l-camera-forum.com/leica-forum/leica-m8-forum/13933-new-backfocus-thread-solution.html

 

but I'm not going to start playing with a wrench before the lens is adjusted...

 

My advice is to not do the wrench thing. I did and it appears to have made things WORSE, not better and it threw off infinity which used to be spot on.

 

I am waiting for a time when I feel like I can be without my kit for 2 months (at least) and I will drop it off personally at Leica NJ for a thorough look over.

 

Unless your camera has the SDS, I'd keep it but since you just bought it I guess you could try a few more samples at your dealer but don't be surprised if they all exhibit the same issue - especially since the problem already existed with the M7.

 

Otherwise, compensate in the viewfinder and enjoy the amazing pictures that you will get!

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My advice is to not do the wrench thing. I did and it appears to have made things WORSE, not better and it threw off infinity which used to be spot on.

 

Unless your camera has the SDS, I'd keep it but since you just bought it I guess you could try a few more samples at your dealer but don't be surprised if they all exhibit the same issue - especially since the problem already existed with the M7.

 

Otherwise, compensate in the viewfinder and enjoy the amazing pictures that you will get!

 

And I'm not exactly known for my dexterity...

 

My dealer has no other bodies available at the moment. As far as I know, only one shop around here (El Corte Ingles) has one in display.

 

I will. Well, I'll try...

 

Olsen: I think I'll send the 50 anyway, with an explanation and some samples. If it doesn't get better, I'll have to consider sending the body too (perhaps in January when days are short and rainy).

 

Thanks for the answers everyone. I'll go to the window now to check if I can see the moon or some stars... :)

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Olsen, the Noctilux is a tricky proposition because it naturally shifts focus as it is stopped down. Adjusting it for proper focus at f1 means back focus at smaller stops. Adjusting for F2.8 means front focus at F1. It is more of a problem in the M8 because of the crop factor causing an effective 33% increase in magnification on equal sized prints.

 

Now that we have a generally available camera that can match or beat the resolution of our lenses we are all learning about focus shift! Not as much of a problem in cameras with AA filters and they have a natural level of "blur" regardless of the lens.

 

 

 

Jose',

 

Wellcome to the forum. I seem to have the same problem as you. My 50 mm 1,0 Noctilux backfocuses with about 10 cm at 2 meters distance. It looks alright - through the viewfinder, at infinity, - and so does all the other lenes I have. None of my other lenses seem to backfocus: A guy here told me that every noctilux have to be adjusted to each and every individual camera. I have had my Noctilux for coding at Solms and hoped that this would help. It did not. It seems to that I have to bring both the camera and the Nochtilux to the Norwegian Leica importer.

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My advice is to not do the wrench thing. I did and it appears to have made things WORSE, not better and it threw off infinity which used to be spot on.

 

 

Well of course it will IF the infinty focus was correct to begin with. In that case it is either the near focus adjustment (not recommended to be done by anyone other then a trained Leica service tech WITH PROPER equipment and tools) or the lens is off and need to be adjusted.

 

I suggest you do the adjustment again to get the infinity correct.

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