Focus markings say 6ft on my lens when the patches match, but it's really 3ft

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binyamin

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Using my mint CLE, I am focusing with the Rokkor 40mm. I match the images on a scene that's 3ft in front of me, and check the lens focus markings and it's saying 6ft. In another case I was able to match the images at the far end at 15ft, when it was more like 4ft. Is something wrong with the CLE? I haven't got the rolls back yet to check on what I got.
 
Will your subject at three feet distance appear sharp on the film
  1. when the rangefinder patches align, or
  2. when the lens is set to 3 ft via the focusing scale?
 
Before concluding that your RF patch is off do as the others said: Aim the lens and camera at a very far away object. About a kilometer / mile away would be ideal. See if the patch coincides with the lens set to infinity.

If it does, your RF may still be off, but it may not be the overall RF adjustment but the near (gain) setting.

Also n-thing: check the film results also.
 
binyamin said:
Well the. Again why would the lens be off?
Click to expand...

I didn't say that the lens would be off. But it's also a possibility. There are old and used items with an unknown history and it's impossible to retroactively know what was done and what hasn't been done to them.

Regarding the lens: The focus scale could have slipped, this would just be an optical concern and wouldn't affect practical use at all. I've seen a bunch of things that can be wrong with RF lenses: misplaced shims, mistakenly added shims, a filed RF cam, the RF cam screwed into the wrong location, the RF cam shoved in at an angle, etc. etc.

I've repaired dozens of cameras and lenses, and the main thing I learned is that you have to be systematic in your trouble-shooting.

So instead of second guessing the advice offered by me and other RFFers here, how about you go about addressing the problem in a methodical fashion instead throwing out wild theories about this or that being off?

1. Check infinity coincidence of the Rangefinder with the lens in question
2. Check infinity coincidence of the RF with another lens
3. See the results on film with the lens in doubt:
3.1. Focused with the RF
3.2. Focused with the lens focus scale
3.3. Focused at something far away with the hard infinity stop of the lens (regardless of RF reading)
4. See the results on film with another lens:
4.1. Focused with the RF
4.2. Focused with the lens focus scale
4.3. Focused at something far away with the hard infinity stop of the lens (regardless of RF reading)

This will give you a much clearer picture as to the issue VS wild guesswork and insistence that it's this or that.
 
TenEleven said:
I didn't say that the lens would be off. But it's also a possibility. There are old and used items with an unknown history and it's impossible to retroactively know what was done and what hasn't been done to them.

Regarding the lens: The focus scale could have slipped, this would just be an optical concern and wouldn't affect practical use at all. I've seen a bunch of things that can be wrong with RF lenses: misplaced shims, mistakenly added shims, a filed RF cam, the RF cam screwed into the wrong location, the RF cam shoved in at an angle, etc. etc.

I've repaired dozens of cameras and lenses, and the main thing I learned is that you have to be systematic in your trouble-shooting.

So instead of second guessing the advice offered by me and other RFFers here, how about you go about addressing the problem in a methodical fashion instead throwing out wild theories about this or that being off?

1. Check infinity coincidence of the Rangefinder with the lens in question
2. Check infinity coincidence of the RF with another lens
3. See the results on film with the lens in doubt:
3.1. Focused with the RF
3.2. Focused with the lens focus scale
3.3. Focused at something far away with the hard infinity stop of the lens (regardless of RF reading)
4. See the results on film with another lens:
4.1. Focused with the RF
4.2. Focused with the lens focus scale
4.3. Focused at something far away with the hard infinity stop of the lens (regardless of RF reading)

This will give you a much clearer picture as to the issue VS wild guesswork and insistence that it's this or that.
Click to expand...

Appreciate all this and I wasn't second guessing, in fact I'm a total RF noob, I was just curious because the possible reasons for lens error were not easy for me to imagine, so I appreciate the breakdown. I am indeed working through your list and appreciate it greatly.
 
Where are you binyamin? Perhaps someone on rff local to you can check it out. If you were in LA I would just slap that lens on my M240 and immediately could tell you where the problem lies.
 
OK, a little confusion here. Infinity is normally reached by 100'-200', not at a kilometer.

The other thing is that the ONLY way you can ck this for yourself w/o getting too involved w/ lens collimation is: put the camera on a tripod, open the back, put the lens on "B", place a bit of ground glass on the film rails, put the lens on infinity, and see if the image on the ground glass is sharp using a loupe. That's exactly how you focus a LF camera in order to confirm that the image will be sharp on the film.
 
Steve M. said:
OK, a little confusion here. Infinity is normally reached by 100'-200', not at a kilometer.
Click to expand...


For a lens, sure. But not necessarily with the rangefinder itself. I remember being surprised how far away I had to focus with my Zeiss Ikon (modern M mount version) to get the focus patch to line up at infinity. Was easily a kilometer or more.
 
jonmanjiro said:
For a lens, sure. But not necessarily with the rangefinder itself. I remember being surprised how far away I had to focus with my Zeiss Ikon (modern M mount version) to get the focus patch to line up at infinity. Was easily a kilometer or more.
Click to expand...
True, Jon, but for the benefit of those reading who are still feeling their way through these concepts—it may be worth emphasising that, regardless of the actual linear distance at which a longer or shorter lens hits its effective "infinity" focus—lens and patch should, ideally, always be at infinity together when the lens has hit its infinity stop and only then. The cam gain of a particular lens must be machined so that, regardless of its focal length, whatever the lens actual point of focus is, will be replicated by the distance at which the patch is aligned.

Thinking out loud, I suppose we can extrapolate from this that, the shorter the lens, the less pronounced the change in precise focus distance will be as the range is set towards infinity—the rate of change will be very, very gradual, compared to a long focus lens. And this must necessitate higher precision in making the cam of a short lens, if it's going to arrive at infinity precisely with the highly accurate RF that features a long virtual infinity.
Does this make sense to you?
Cheers
Brett
 
My experience with a Leica CL and 40mm Summicron was that I couldn't adjust the rangefinder myself to get it right. I have managed to do this with my Barnack Leicas and my M6, but found the CL too hard. So I would say take the CLE and lens to a competent Leica rangefinder technician and get them adjusted professionally.
John Mc
 
Good advice from TenEleven and several other members.

Trying to rephrase in compact way. Three items related to distance adjustment
1. Rangefinder
2. Lens distance scale
3. Actual film plane sharpness
You report evidence that (1) and (2) disagree. As pointed out by others, this does not prove that (1) is faulty (although it's more likely that the RF is off than the lens distance scale). Agree with Steve M. that a ground glass will be more effective than film for debugging (although final proof is with film). According to the outcme of teh diagnostic, consider the advice of mcfingon.
 
I was just in NYC yesterday and actually only left 2 hours ago. I had a bag of camera gear and a few tools. I could have at least told you if your issue was with your RF or your lens.
Oh well. Ships passing in the night.
There are a lot of Leica shooters in NYC that could help you out but since it is a CL, it may be a little more difficult to adjust than the standard Leica M or Barnack, so it still may need to go to a repairman.
Phil Forrest
 
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