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  1. #11
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    Nothing like having a watchmaker among us!

  2. #12

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    As E. von Hoegh said, This is slow curtain travel at the slower speeds, not a problem with the slow shutter speeds. You can see in some of the shots as well that the side in the direction of travel is exposed longer than the upstream side of travel.

  3. #13

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    Quote Originally Posted by Lamar View Post
    As E. von Hoegh said, This is slow curtain travel at the slower speeds, not a problem with the slow shutter speeds. You can see in some of the shots as well that the side in the direction of travel is exposed longer than the upstream side of travel.
    Since I havn't seen the camera, I do not know, but I'm presuming it has dry or thick lubricant on the spindle of the drum. This assembly has a drum for the first/opening curtain, two coaxial - top and bottom - rollers for the tapes of the second/closing curtain, and a floating disc that has a pin which works in slots in the top of the drum and top roller to cap the shutter when you wind it. If the disc is sticky on the spindle it can cause this problem, the wider the curtain opening the closer to a full circle the disc travels.Stiff lube on the spindle elsewhere will cause trouble too. This is pretty similar to the design used on say a Leica III or IIIa; here's a link - http://www.pentax-manuals.com/repairs.htm
    I have an old Canon IIb that had the same issue, 65 year old lubricant gets almost like shellac.

    Edit for clarity
    Last edited by E. von Hoegh; 01-07-2014 at 05:25 PM. Click to view previous post history.

  4. #14
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    How's progress, Lamar?

    Maizenberg is the mandatory book on the subject, I think. Google, download, enjoy, if you haven't yet. I've seen it online in English and Russian.

    I've noticed similar behavior BTW, that is the rear curtain getting slow, while it was getting better and better as the shutter speed went up. It's illogical, I know. And lubrication helped a lot with the issue.

    BTW, Zeiss Ikon filters (~42mm slip-on) fit on lenses with 40,5mm thread (checked with Jupiter 8), and original cap still works, fits well inside the filter.

    Cheers!
    Use the Force, Luke!

  5. #15

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    I have made some progress. I'm learning more than really fixing anything though. I de-tensioned the rear curtain spring by half a turn and that seems to have helped. I can still see one side of the frame is a little under exposed though. I will most likely de-tension the rear curtain spring another half turn and test again. I also think the front curtain has been over tensioned, winding seems a bit stiffer than my others. I read where starting tension on these springs should be 5 turns for the front curtain and three for the rear. I almost want to just release the springs and start from scratch so I know exactly where I am on them. I wish there was an easy way to really test the shutter speed accuracy and timing.

    I haven't committed to a full disassembly and CLA yet but I did put a drop of Break Free CLP oil at a few key points to see if it would help. It did seem to make the slow speeds much more reliable. They work correctly most of the time now. I did not have a single problem with the slow speeds yesterday...... Keeping that broken Zorki-4 was the best $15 I could have spent though. I have been able to learn and test on it before I do anything to my good ones.

  6. #16

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    I found an interesting post over at Rangefinder Forums regarding checking relative shutter curtain speed. Such a simple procedure to a seemingly diffcult problem. It shows how to use a CRT to check/adjust tension on your shutter curtain springs to ensure they travel at the same speed. I have checked mine and the results were consistent with what I was seeing in the pictures from each on my Zorkis. I have now adjusted according to the post. The next roll will tell.....

    http://www.rangefinderforum.com/foru...ad.php?t=30343

  7. #17

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    Quote Originally Posted by Lamar View Post
    I found an interesting post over at Rangefinder Forums regarding checking relative shutter curtain speed. Such a simple procedure to a seemingly diffcult problem. It shows how to use a CRT to check/adjust tension on your shutter curtain springs to ensure they travel at the same speed. I have checked mine and the results were consistent with what I was seeing in the pictures from each on my Zorkis. I have now adjusted according to the post. The next roll will tell.....

    http://www.rangefinderforum.com/foru...ad.php?t=30343
    That post is dated 2006 and is just about certainly based on the frame and scan rates of the no-longer-in-use-for-broadcast NTSC 3.58 system. Unless you used an old TV (CRT not flatscreen) with an NTSC signal, the results won't be accurate for estimating shutter speeds. The new system may still show valid info for relative speeds of the curtains though. Leitz used a similar method before TV - http://www.skgrimes.com/library/old-...shutter-tester

    By "rear curtain" do you mean the first/opening or second/closing curtain? They are not always in the same relative fore-and-aft positions on all cameras.
    If you really want fun get a Kiev - metal slats running up and down!

  8. #18
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    Quote Originally Posted by E. von Hoegh View Post
    That post is dated 2006 and is just about certainly based on the frame and scan rates of the no-longer-in-use-for-broadcast NTSC 3.58 system. Unless you used an old TV (CRT not flatscreen) with an NTSC signal, the results won't be accurate for estimating shutter speeds. The new system may still show valid info for relative speeds of the curtains though. Leitz used a similar method before TV - http://www.skgrimes.com/library/old-...shutter-tester

    By "rear curtain" do you mean the first/opening or second/closing curtain? They are not always in the same relative fore-and-aft positions on all cameras.
    If you really want fun get a Kiev - metal slats running up and down!
    Well I still use an old TV with the digital converter box. Doesn't the box convert the digital signal back to the 525 line, 7875/30 frame system?

  9. #19

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    I threw out most of my CRT based video gear last year during a clean-up but luckily I'm a pack-rat and kept a couple of my small NTSC TV's just in case. Yes, rear curtain is the second/closing, front curtain is the first/opening. That nomenclature was from Nikon manuals regarding flash sync, I'm sure others use the same reference. I never knew if "rear" was referencing physical position when looking down on the body or just the fact that it was triggered last in the sequence, bringing up the rear... :-)

    Quote Originally Posted by E. von Hoegh View Post
    That post is dated 2006 and is just about certainly based on the frame and scan rates of the no-longer-in-use-for-broadcast NTSC 3.58 system. Unless you used an old TV (CRT not flatscreen) with an NTSC signal, the results won't be accurate for estimating shutter speeds. The new system may still show valid info for relative speeds of the curtains though. Leitz used a similar method before TV - http://www.skgrimes.com/library/old-...shutter-tester

    By "rear curtain" do you mean the first/opening or second/closing curtain? They are not always in the same relative fore-and-aft positions on all cameras.
    If you really want fun get a Kiev - metal slats running up and down!

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