Confused by back focus

[huwge]

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I am a little confused and having searched the forum am still no closer to a clearer understanding.

 

Is back focus a problem with the M8 body or with the lens?

 

My 50mm asph Summilux back focuses by > 1.5 cm across all apertures, at close range (< 3m). All my other lenses seem fine (24 2.8; 35 2 asph; 50 2 rigid; 75 1.4 and apo 90), with exception of old 35 'lux that is already in Solms.

 

Now 15 mm may not seem a lot and I certainly don't seem to find evidence of problems with my M7, but I have been avoiding using the lens for portraiture because images lacked the sharpness of film. The rigid 'cron and 'lux 75 both perform brilliantly on the M8.

 

Given the limited variance when compared to other forum posters, is this something that would / could be corrected in the QC phase of getting the lens coded or do I need to send it in with the specific requirement for focusing to be corrected? Are there other options?

 

Huw

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[jaapv]

I'm gonna get flamed again:( Before you start blaming the camera and/or lens, have your eyesight checked and hold the correction glasses of the optician between the viewfinder and your eye to see if that improves matters, then, having eliminated that variable, start on the infinity focus of the camera and only after that have the lens adjusted.

[huwge]

Jaap,

I would agree with you, but why is it only this one lens and always at near distance? If I can get it right with 24, 35, 50 cron, 75 and 90 why not the 50 'lux? Also, I did follow some of the guidelines on how to check this - fixed object, tripod etc.

Huw

 

PS - with new glasses and contact lenses, always the 50 lux - never the 75 or 90

[billh]

Jaap,

I would agree with you, but why is it only this one lens and always at near distance? If I can get it right with 24, 35, 50 cron, 75 and 90 why not the 50 'lux? Also, I did follow some of the guidelines on how to check this - fixed object, tripod etc.

Huw

 

PS - with new glasses and contact lenses, always the 50 lux - never the 75 or 90

 

It is probably the lens. It clearly is not an issue with you because your other lenses are fine, but this one is off. I had several lenses that back focused, and currently the 50f1.4 ASPH and the second M8 are at leica to be adjusted to each other. Like you, I quit using the lens, because when I focused on the eyes, the ears were instead in focus. And with glasses I still see at 20 feet what is normally seen at 15 feet, so despite what some say, it is most certainly the equipment and not an issue with my ability to focus the camera. I am worried that if the M8 and 50 mm lens are adjusted correctly, my APO 75 will be out of adjustment when the M8 returns. I was told it will be shipped back on June 25 - whenever it does return I will do the lens focus test (without a tripod this time) and let you know the results. Some people do have cameras that finally focus correctly with all of their lenses (in one case his 4th M8 was the magic one), so apparently this is possible.

 

By the way, for the skeptics, I refocused each lens five times with the 1.25x magnifier and five times without the 1.25x magnifier, and I repeated this test several times, and the results were always the same. I knew the issue before running the tests because I could obviously see the problem in the photos I took, and only did the tests to show Leica the issue.

 

Bill

[huwge]

Bill (or others),

 

if it is the lens, what is the best course of action? Is this something that could be corrected during the callibration of a newly coded lens or is this something that requires more work. It seems to be never less than 1.5 cm and never more than 5 cm, all when wide open. I had not thought to get the 50s coded, but if that is the easiest way to get a fix then so be it. The adjustment of my old 35 lux is costing €440 and I would prefer not to have to pay that over for the 50 if not necessary.

 

I can't believe that on my M8 this lens is absolutely outperformed by a 50 year old 'cron at the same focal length.

 

Huw

[jaapv]

If I were you, I would have it coded forst, mentioning the problem. As they change the mount, it may solve the problem. However, if you don't have it coded ( after all, why should you? The only benefit is having "50" written into your exif.) you would be better off having it checked and adjusted by for instance DAG,or any of the other reputed camera repair shops as that is likely to be faster, less expensive and more certain to solve the problem in one go.

[MP3]

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I got the same issue here, 6 lenses focus perfectly with my M8 while the Noct is obviously back for 1 inch at f1, 1m. I share this currently at another top thread and will get my Noct for adjustment.

[larry]

I haven't had any such focusing problems with my slower "classic" lenses. In browsing similar threads, it seems that only the faster more highly corrected lenses are having these problems -- correct?

 

Larry

[Shootist]

Just to add my $0.02

Last night I did tests with both bodies @ 3' (36") with all the lenses I have on hand, 24 ASPH, 28/2.8 ASPH, 35/2 ASPH, 40/2 Cron-C and new 50 Cron, all my other lenses are in never never land somewhere in NJ. All of them on both bodies acted exactly the same and where dead on at widest apreture and shifted back slightly when stopped down throughout the apreture range. But none of them lost the point of focus at any apreture.

 

Also it is really tough to test focusing on 35mm and below. The gained DOF from the wider lenses makes up for any out of focus adjustment and or focus shift when stopping down. From 28mm down it is almost impossible to tell IF it is actually focusing correctly at your intended point of focus. That is unless your camera or lens is WAY OUT of adjustment.

 

Best think to do is test the camera with at least a 50, 75 or 90mm lens that YOU KNOW is good on another M8 or on film.

[hansg]

Huw, I've got the same problem. It's not you. I tried for months before reaching the inevitable conclusion that the combination of (brand new) 50lux asph and M8 doesn't work. Earlier, I had sent in both camera and lens separately. That didn't solve the problem. After consulting the people in Solms, I recently sent in both. Hopefully they'll solve the problem and I keep my fingers crossed that it will work too with all the other lenses!

 

Hans

[huwge]

Thanks everyone.

 

Must say it is confusing that it is just one lens, that did not misbehave with film and has never been treated badly. Really, a rigid 'cron is just a delight to use with the M8, as are all my other lenses - just a 10 year old 'lux 35 (which in fairness was long due a service) and the 2 1/2 year old 50 'lux. I really don't want to send body and lens to Solms unless I have to.

 

Trying to reach the service department by phone seems to be a labour of love and I do not have the time to constantly hit re-dial. I have sent an e-mail to see what reaction that gets me.

 

Huw