Infinity Focus Issue

S

sepha.kay

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Jul 25, 2018
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I've been really annoyed these past few months. For some odd reason my infinity focus always seems to shift very slightly after hours of use. I always double check my readings before I declare it's finished (Both infinity and 1M) and I feel very confident about it, but it always finds its way slightly off. It's not dramatically off, but enough to say "it needs a small tweak". Could it be because of movement? I have it around my neck and its usually bumping against my stomach most of the time, but from what I know that shouldn't have an affect on the RF.



Any ideas to why this may be happening? Maybe Flange shift? Lens mount/demount?



Would appreciate the help!


EDIT: The camera I am using is a 1953 Zorki 1 C with a Jupiter 8 lens
 
It would probably help if you said which camera and lens you have. It sounds like the rangefinder could be drifting out of calibration, as if an internal adjustment is loose. But are you always using the same target, and/or always selecting a test target far enough away to be at "infinity?" If it happens while you are out walking with the camera, it seems like you might be using a different target, and at a different distance, each time you check. A distance of several miles away is recommended. A radio or TV tower in the distance is good. The moon is better!
 
Rob-F said:
It would probably help if you said which camera and lens you have. It sounds like the rangefinder could be drifting out of calibration, as if an internal adjustment is loose. But are you always using the same target, and/or always selecting a test target far enough away to be at "infinity?" If it happens while you are out walking with the camera, it seems like you might be using a different target, and at a different distance, each time you check. A distance of several miles away is recommended. A radio or TV tower in the distance is good. The moon is better!
Click to expand...


Sorry about that! Forgot to mention the camera. I have a 1953 Zorki 1 C with a Jupiter 8 lens


and yes, I focus far enough for infinity. I even focused on the Moon the other time I fixed the infinity. Happened again...
 
Hi Sepha :D

No solution from me but I had the same issue with a 120 folding camera. Got the rangefinder perfectly aligned, left it overnight and in the morning it was way off again :confused: Goblins.
 
Arbitrarium said:
Hi Sepha :D

No solution from me but I had the same issue with a 120 folding camera. Got the rangefinder perfectly aligned, left it overnight and in the morning it was way off again :confused: Goblins.
Click to expand...

Next time make a note of the frame number last thing at night. As we can't see them the frame may be blank but that's assuming they are taking photo's and haven't RTFMed...

Regards, David
 
sepha.kay said:
I've been really annoyed these past few months. For some odd reason my infinity focus always seems to shift very slightly after hours of use. I always double check my readings before I declare it's finished (Both infinity and 1M) and I feel very confident about it, but it always finds its way slightly off. It's not dramatically off, but enough to say "it needs a small tweak". Could it be because of movement? I have it around my neck and its usually bumping against my stomach most of the time, but from what I know that shouldn't have an affect on the RF.



Any ideas to why this may be happening? Maybe Flange shift? Lens mount/demount?



Would appreciate the help!


EDIT: The camera I am using is a 1953 Zorki 1 C with a Jupiter 8 lens
Click to expand...

Can't offer a definitive answer but there's a factor you may not have accounted for - maybe factorS. First off, the camera is old and isn't as precision-made as something more expensive. Years of wear in the RF mechanics and/or lack of original precision mean there's likely to be a small amount of play and backlash in the mechanism. When you've finished adjusting, try moving the lens end-to-end and back to the starting point (infinity). Does the RF remain in calibration at the time? Repeat the end-to-end before rechecking it again. Let us know what the outcome is but bear in mind you may well have to live with it.
 
wolves3012 said:
When you've finished adjusting, try moving the lens end-to-end and back to the starting point (infinity). Does the RF remain in calibration at the time? Repeat the end-to-end before rechecking it again. Let us know what the outcome is but bear in mind you may well have to live with it.
Click to expand...


I've tested this out. It stays in place, but after a while it just shifts on its own again. Always the same amount of movement as well. Maybe if I adjusted it a tiny bit past the infinity and let it shift on its own, it should sit in place then? maybe I should give that a try.
 
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