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Mdawg12
Tinkerer
Username: Mdawg12
Post Number: 1
Registered: 06-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, June 02, 2010 - 04:48 pm: | 
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Hi, I recently got a roll of slide film back and 30 of my 36 exposures were pure black--not underexposed, but NOT exposed. The other six were normal. I used my Nikon F, which I've only been using for a month but it's been great until now.
I know my exposures were off by like a stop or two at most in either direction (via a sekonic 758cine meter, and I bracketed) so it's an issue with the shutter not working so far as I can tell and the problem is intermittent. I know the mirror raised up while I was shooting because the viewfinder went black and I felt a click--so I was very surprised to find a problem.
My camera has a serial number around 65000, so it has a titanium shutter, which appears to be in great shape. I'm using primarily pre-AI prime lenses and the problem seems to show up on all of them. It's not the aperture incorrectly going to f22--the exposures are completely black, not just egregiously underexposed.
Could I have loaded the film wrong and so the shutter sometimes failed to open? Maybe the back plate was putting pressure on it? When I try the camera out without film the shutter opens normally. Is this a known problem on the F or older cameras in general?
Thanks for the help. |
Milosdevino
Tinkerer
Username: Milosdevino
Post Number: 9
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, June 02, 2010 - 05:05 pm: |
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Which Nikon F model is it? I have had a similar experience with an F4, and it was traced to a faulty shutter, which Nikon replaced under warranty. The way I found the cause of the problem was to take the lens off and fire the shutter whilst looking into the camera through the lens mount hole. If you try this you should see the mirror move up but the shutter stay in place. |
Mdawg12
Tinkerer
Username: Mdawg12
Post Number: 2
Registered: 06-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, June 02, 2010 - 05:22 pm: |
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It's an original Nikon F, circa 1964. I tried the test you described and the shutter fired correctly (from bulb to 1/1000 second).
It seems I may have misaligned the f-stops on the lens with those on the camera body on occasion...but this would seem to cause missed exposures, not shutter problems--unless the shutter release (but not the mirror) is fired contingent on the aperture firing correctly. Thanks for the help, though--that's what I assumed, too, until the test seemed to indicate the shutter was okay (at least without film loaded). |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 1091
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, June 02, 2010 - 08:57 pm: |
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Nothing about loading the film should cause this, and I can't think of anything the lens could do either... in some cameras, a stiff lens can block the shutter from firing, but it typically does so by blocking the mirror from coming up - I can't think of anything that would be undetectable as it happens, as you describe. I can picture this happening in a leaf shutter SLR, or in one with an electronic shutter - but in a Nikon F, it's very odd. I have never disassembled this shutter to the point of understanding how something like this might come about..... |
Edward8
Tinkerer
Username: Edward8
Post Number: 20
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, June 02, 2010 - 10:57 pm: |
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Odd indeed.
Where were the six "normal" frames? At the beginning or end of the roll? Not sure what I'm getting at myself but the answer might shed some light on the problem, so to speak ... |
Mdawg12
Tinkerer
Username: Mdawg12
Post Number: 3
Registered: 06-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, June 02, 2010 - 11:16 pm: |
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I checked four good frames and they read 2, 3, 12, and 14. So I'm thinking the beginning of the roll was fine, then something happened at the fourth shot (which is black)...and it slowly went all bad.
I originally thought the first 12 or so exposures were bad; thinking back, it's likely it was the LAST 12 (well, actually, more like 20). |
M_currie
Tinkerer
Username: M_currie
Post Number: 231
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, June 03, 2010 - 09:57 am: |
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When you test by dry firing with the lens off, it helps to look through it from behind. Any shutter anomaly will show up pretty clearly then. Make sure you try it at different speed settings. It's possible, for instance, that the shutter is operating properly at speeds of 1/60 or less, where the shutter opens fully before the second curtain closes, but that it's not opening the slit on higher speeds (or vice versa). The entire shutter operation changes between 60 and 125. That might make the failure appear random when it is actually consistent. |
Mdawg12
Tinkerer
Username: Mdawg12
Post Number: 4
Registered: 06-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, June 03, 2010 - 12:01 pm: |
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That's the best theory I've heard yet. Currently, looking through the back of the camera, all shutter speeds appear to work okay (at least so far as I can tell; the shutter clearly opens). And my last roll of film, which I just got back today, came out 100% normal.
That said, it seems totally plausible (though still weird) that I loaded the film wrong on the messed up roll and that somehow interfered with shutter speeds of 1/125th of a second and shorter. Thanks for the insight. Fingers crossed for now... |
Edward8
Tinkerer
Username: Edward8
Post Number: 21
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, June 04, 2010 - 05:39 pm: |
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Whew. Had me baffled. Let's know how it goes ... |
Ethostech
Tinkerer
Username: Ethostech
Post Number: 154
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, June 08, 2010 - 09:27 pm: |
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I have had many similar such problems over the years - and with various SLR models. Currently I have it with a Pentax P30T,
The issue is invariably dried out lube within pertinent areas of the mirror-box mechanism by which the shutter is triggered.
Since there is some shutter interface mechanism under the baseplate, then a very light oiling of all pivots and little grease on all visible cams, mostly fixes such shutter intermittency. But not always. If such under baseplate attention and a daily exercise of the shutter through around 20 cycles a day for about a week - does not send the problem away - then I'm afraid you'd be looking at pulling the mirror-box out. (No mean feat unless you are experienced).
That's my take on the subject - for whatever it is worth.
Best. |
