Is it the lens or is it the camera (focus)?

[Peter Wright]

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When I got into the Leica system some months back, I got an 90 Elmarit M, a 50 Summilux M, and an M240.  After taking some portraits at f/2.8 I noticed that the focus point was about 3-4 inches behind the eye I had focused on.  I did some tests on a tripod with a Lens align target at about 8 feet, and confirmed that the lens/camera is focusing 3.5 inches behind the target.  When I attach my 50 and do the same test, but at f/1.4, there is a slight back focus of about 1-2 inches (but difficult to achieve consistently).  With a 35 1.4 attached and at the same distance, I can see no focus issues, but this could be due to the wide angle lens dof.

 

Now I am wondering whether to send off the 90 Elmarit, the M240, or both, or just ignore it as too small to worry about.

 

Any of you long time users got any advice?

 

Thanks in advance.

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[Echo63]

Does the rangefinder properly align at infinity ? (Try focusing on the moon one night)

That was the first clue mine was out.

I did have issues focusing a 50 nokton and 90 summicron in the shop before that though, but my 50 elmarit hid the focusing issue.

 

Chances are its the rangefinder being slightly out.

A good local Leica repairer should be able to fix this for you.

[jaapv]

If it bothers you take the camera and lenses into any competent repair shop that does Leica and have them calibrate the system. You can, of course, send the system in to Leica, but it will take (far) longer and cost (far) more.

[250swb]

Have you confirmed your tripod rangefinder tests by cross checking using Live View to focus?

 

 

Steve

[Peter Wright]

@Echo63:  Everything is fine at infinity.  You are saying that in this case, the lens is fine and it is the camera I need to have adjusted?

 

@jaapv:   I called up a well known Leica repair person in my part of the world (Toronto), who told me that lens adjustment requires particular equipment that he doesn't have, and suggested sending the lens to NJ.  I would like to avoid that if possible: especially if it isn't necessary.

 

@250swb:  Yes.  It is by comparing Live View to the rangefinder (with a 1.4 magnifier) that I do the tests.

 

Peter.

[Echo63]

@Echo63:  Everything is fine at infinity.  You are saying that in this case, the lens is fine and it is the camera I need to have adjusted?

 

@jaapv:   I called up a well known Leica repair person in my part of the world (Toronto), who told me that lens adjustment requires particular equipment that he doesn't have, and suggested sending the lens to NJ.  I would like to avoid that if possible: especially if it isn't necessary.

 

@250swb:  Yes.  It is by comparing Live View to the rangefinder (with a 1.4 magnifier) that I do the tests.

 

Peter.

 

because it is two lenses that are off, in the same direction, I assume that it is the RF calibration that is slightly off (in the camera)

 

here is what happened with my camera.

the camera was pin sharp from the factory (with my 50 summarit f2.5)

after a year or so, it wasn't quite so sharp, but not enough to worry me, i just thought it was sloppy technique.

i tried a few lenses at my local dealer, everything appeared fine, except for a 90 summicron, and a voigtlander 50 f1.1 

both back focused quite badly.

I didn't do anything about it, assuming there was something wrong with both lenses, because my 50 was still Ok.

I got a 90 M Rokkor, the focus was off a bit sometimes but photographing moving kids, i still got the occasional sharp frame, i didn't do any tests, because i figured it was a new lens, and i needed to be more precise in my focusing.

one day i took a photo of some cranes at fremantle port.

when the rangefinder images matched, the pic was blurry, if i racked the lens out to infinity, it was sharp, but the RF split image was off.

it was at this point i realised i had a problem.

I adjusted the infinity adjustment, using directions found here on the forum (i have tried to hunt the link down, but can't find it, i know it is in my history on a PC at work, because i printed the pics from it the other day, so i will dig it up and post it here) and have enjoyed perfect focus on both the M Rokkor and Summarit since - I really should drop back into the Store and try their Nokton again....

 

 

To sum up - i think one of your RF adjustments is off - either the infinity adjustment or the arm length.

i don't recommend poking around inside your camera, instead letting a technician check it for you, and adjust if necessary (they should be able to at least help diagnose where the problem is, either the RF or lenses)

do you have a fellow Leica user close by ? you could try your lenses on their body and your body with their lenses.

 

 

EDIT - found the thread http://www.l-camera-forum.com/topic/118043-m9-coincidence-at-infinity/page-1

should give you a bit of an idea about how the RF works, and what could be wrong.

[jaapv]

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Hmmm.... I'd try another repair person - except for very fiddly lenses like the floating elements ones (like for instance the Summilux 50 asph, ot the 35 Summilux asph FLE) the adjustments are well within the scope of a competent repairer.

Normally one would use an optical bench - but a little trade secret is that the LV on the M240 make life easy.

[tobey bilek]

Do the lenses have a focus shift, i.e. different at 2.8 & 8.  RF can not compensate.

 

My limited experience tells me back focus at close range is common,  75 1.4  75 APO   35 2.0 ASPH   .   These are all recently calibrated lenses & several cameras.   They all work at infinity.

 

I would suggest some test photos full open and F8 at 3 feet.

[Peter Wright]

After some relentless testing, with additional lenses (a 75 f/2.0 as well as the 90 f/2.8, and 50 f1.4) and an M246, I am starting to believe that at least some of the back focus may be my technique  .  The more I tested, the less the problem became!  However, I do believe that there is still a small back focus that is most noticeable when using the 90 Elmarit M and my M240, but not as much as I thought.  I will probably pass this lens/camera combo to a good technician for minor adjustment.

 

Incidentally, in the course of doing all this, I have discovered a new appreciation for my lenses.  Focusing the 90 on a distant building (at "infinity"), the rangefinder window is fully aligned, the lens is at the end stop, aperture is wide open, and I can pick out the details of the bricks in the walls of the building when I magnify to view!  The 75 wide open was almost as sharp, but not quite.

 

Now I want to stop all this testing and take more pictures. 

 

Peter. 

[lct]

[...] Focusing the 90 on a distant building (at "infinity"), the rangefinder window is fully aligned, the lens is at the end stop, aperture is wide open, and I can pick out the details of the bricks in the walls of the building when I magnify to view!  The 75 wide open was almost as sharp, but not quite. [...]

 

Sure if you mean in edges and corners but in the center of the frame the 75/2 is slightly sharper, as far as my copies are concerned at least. My 90/2.8 has been optimized for digital but the 75/2 is really outstanding there. Could be a hint that your RF needs some adjustment. FWIW.