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01-05-2016, 09:53 PM   #1
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Two OM-1 bodies, two problems

I picked up two OM-1 bodies today. Both have problems. I think one is shot in that the meter seems wildly inaccurate (off by about five stops, but I haven't tried it outside.) The other has an interesting problem I can't figure out. The shutter speeds seem accurate at 1/125th and faster. Below that, they all fire at 1/125th. I thought the OM-1 was all mechanical, so this problem confounds me. And since it has a working meter, I'm a bit frustrated and hoping there's an easy answer I haven't found online. Does anyone have any experience with this problem?

01-06-2016, 05:39 AM - 1 Like   #2
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That almost sounds like the second curtain on your shutter isn't delaying like it ought to on slower shutter speeds. You may know this, but the focal plane shutters on film cameras change operation slightly right around the flash sync speed. On slow shutter speeds, the first curtain will open, then the second curtain will follow at the appropriate time depending upon what shutter speed you set on the camera. The flash sync speed is usually the fastest shutter speed where the entire film plane is exposed...meaning, the first curtain has cleared the film plane and the second curtain hasn't started across yet. For higher shutter speeds, the second curtain starts before the first curtain has cleared the film plane so essentially the film is exposed by a strip of light moving across the plane (or top to bottom, depending upon what kind of shutter you have). That's why, if we use a shutter speed faster than the given synch speed, we get frames where part of it is exposed right and part have black strips. Since it's your slower shutter speeds that aren't working right, that makes me think it's something with your second curtain. This is a long shot, but sometimes little chips of film can get in the shutter track, impede the motion of the curtains, and cause the timing to be irregular. You might try popping the back open, setting the camera on "B", then open the shutter and see what you can see. That's probably not the issue, but hey...it's free! lol Good luck! I hope you get your cameras working. I'm a long-time Pentax guy, but back in the day when my mom asked what camera she should buy, I had to recommend an OM-1. They're just tremendous little cameras.
01-06-2016, 12:14 PM   #3
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DC, that sounds like my project this evening (thank you for that link, which was very helpful.)

Taomaas, bulb also fires at 1/125th. But I will try and see if there's something jamming up the mechanism, either film or light seal material. It could be a combination of problems with this camera.

With luck, I can get figure it out. I have a beat-up but mechanically functional OM-1 I can compare this new one to if I don't see any obvious issues with the mechanisms.
01-06-2016, 01:38 PM   #4
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QuoteOriginally posted by K David Quote
Taomaas, bulb also fires at 1/125th.
Well, duh! That makes sense if there's a problem with your second curtain. Sorry...I should have thought of that.

01-07-2016, 12:24 AM   #5
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Well, that worked! Took about five minutes. I took the inside bottom off the malfunctioning camera and couldn't tell why it wasn't working. BUt I did notice as soon as I did that that 1/30th and 1/8th came back. Withing about a dozen test fires, I had everything from 1/4 and faster back. I opened up the one with the bad meter and good mechanics and noticed that 1- the faulty shutter sped one had two rusted screw caps inside the shutter box and 2- some lever wasn't engaging when bulb was pressed.

Eventually, just with use, I was able to get all the timed shutter speeds back, but bulb simply was not working. The lever causing the problem is one next to (on the right, facing into the camera) the top of the geared cam that connects to the shutter speed dial. It was pretty stiff, as was the rest of the inner mechanism. So I put some rubbing alcohol on a Q-Tip and dabbed the reachable gears about five times. I ran each shutter speed twice and then tried bulb again. On the third try, bulb worked! I had a bit more work to do, though, because I had to tap the faulty lever with my finger to get bulb to disengage, and that would be inconvenient at best during shooting.

So I put a bit more rubbing alcohol on that lever and tapped it a few times. It seemed that a spring controlling its freedom to move was not cooperating (this spring happens to be around one of the screws with a rusty cap, so there may be a connection.) Forcing the lever to move a bit more than it wanted to (by like 1mm) did the trick and bulb worked as required consistently for about 20 tries. I let it sit while I wrote this, and bulb still works. It looks as though it was a combination of thick lubricant and possibly some glue that had been put in the wrong place (the bottom plate on this camera had two glue spots whereas the other only had one and the different glue spot on the underside of this camera's plate corresponded to one of the inner levers and springs.)

Now to debate whether or not I want to try and diagnose the faulty meter in the other one.

Thank you again, both, for your help.

QuoteOriginally posted by TaoMaas Quote
I should have thought of that.
No need to apologize. I had to go back and check.
01-07-2016, 06:28 AM   #6
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Cool! Glad you got it figured out!
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