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Mattthegamer463
Tinkerer
Username: Mattthegamer463
Post Number: 1
Registered: 06-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, June 19, 2013 - 09:37 pm: | 
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Hi, new member here!
I recently bought a Canon 7 on eBay and got lucky, everything seemed okay, so I ran a roll through it and some of the images came out with a very odd light leak.
http://img.photobucket.com/albums/v321/mattthegamer463/20130619_230634-2.jpg
Sorry about the picture quality but its hard to shoot a negative with a camera without a light table.
As shown in box 1 there is a repeating trend of half proper/half overexposed frames. The image is still there faintly, not 100% blown out, but the light has also exposed the sprocket area of the film so I am thinking it must be very bright. It happens on shots in the sun but also shots that were indoors, but the camera may have been exposed to sunlight while that frame was behind the shutter. There are also shots in sunlight with no issues at all. The issue was severe for the first half dozen frames, then almost disappears the rest of the roll (or just leaving a vertical stripe overexposed and not half the image) but even on frame 35 there is a tiny indication of this issue.
At first I thought one of the curtains was half closing/opening and majorly affecting the exposure but this problem happens on high and lower (1/30) speeds. I checked for light leaks and couldn't find anything. When looking through the shutter at a bright light at higher speeds I don't see a discernible change in brightness from one side of the frame to the other, although 1/1000 is a little slow.
Basically I'm out of ideas about what it could be. Next thing to do will be a test roll documenting exposure to light/shade and lens cap on/off, etc. But I was hoping someone might have an idea on here.
Thanks for any responses, they are much appreciated.
PS. I can't seem to get the bottom plate off the camera due to the metal ring around the tripod thread, it won't come loose. The repair manual shows it needs to be removed for the plate to come off but my retaining ring pliers pushed right through the aluminum before it would move. Can't figure it out and I'm bummed I scratched up the ring.
Again, thanks for any help. |
Mikeb
Tinkerer
Username: Mikeb
Post Number: 25
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, June 20, 2013 - 09:29 am: |
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Can you open the back, set the shutter to some slow speed, and fire it off a few times while watching the shutter curtains?
I have an old camera that one curtain hangs on, but as it is exercised the curtains "hang time" becomes shorter until it hardly hangs. Then when it sits unused for a while it starts over. Maybe you have a similar situation. |
Mattthegamer463
Tinkerer
Username: Mattthegamer463
Post Number: 2
Registered: 06-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, June 20, 2013 - 03:42 pm: |
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Thanks for the post Mike. I have watched the curtains at all speeds and both the front and the back move very quickly, seemingly just as fast and don't appear to get stuck. I measured the speeds with a device I made and they are nominally accurate at all settings. I am wondering if maybe I had a sticky shutter that now, with exercise, has stopped getting stuck around halfway across the frame, as you say.
This could be possible but I am thinking maybe not since the light in the frame bleeds into the sprocket area of the film, that just seems really strange to me. There is still image visible inside the bad area, if it was so exposed that it was getting around the framing edges then the actual image should be totally whited-out, I would think. |
Fidji
Tinkerer
Username: Fidji
Post Number: 46
Registered: 12-2011
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, June 21, 2013 - 05:06 am: |
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As you say, the light bleeds into the sprocket area and there is an image beneath the dark lines. Looks to me that the image is exposed OK, but when it is wound on to the next frame, the image is exposed to a thin line of light whilst on the rewind reel.
Have you checked the opening catch side for light leaks? Some cameras with chrome catches were fine if used in their leather cases, but leaked light if the catch was distorted once removed from their cases. |
Mattthegamer463
Tinkerer
Username: Mattthegamer463
Post Number: 4
Registered: 06-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, June 21, 2013 - 04:51 pm: |
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I've took a look and I don't see anything wrong but I did notice the foam on the hinge side of the door is totally wrecked, so I've put a piece of craft foam in there for now to test it. I've loaded the camera with a roll and I will do some test shots but the sun has disappeared for now so it will have to wait until tomorrow at least.
I'm going to test shots of bright areas, shots with the sun in the frame, a shot with the lens cap on but with the sun on the camera, and holding the hinge side out to the sun to try to make some sort of effect on the film through there.
Thanks for the tip I'll see what happens. |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 1315
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, June 21, 2013 - 08:55 pm: |
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Here's how I hunt for light leaks - it requires a roll of film:
Load the camera, put a lens cap on it and advance the film several frames in the dark, ending with the shutter cocked. Now take the camera out for a long walk in the sunshine, making sure to expose it to direct sunlight from all angles. Next, take ONE clear picture. DO NOT ADVANCE THE FILM. Return home, go back into the dark and rewind the film and develop it.
After the film is developed, find the one exposed frame on it and cut several inches of film with that frame in the center. Set the film in place in the camera with that exposed negative in the film gate (remember the image is upside down on the film).
Inspect the film carefully for any sign of light leaks. The location of any leak marks you find on the film will exactly correspond to the location of the leak in the camera when the film is in place as noted above.
This may sound a little tedious, but it's a lot quicker than just running film through the camera and not knowing what position the film was in when the light leaks hit it. |
Hollenbj
Tinkerer
Username: Hollenbj
Post Number: 132
Registered: 03-2012
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 22, 2013 - 04:31 pm: |
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Brilliant Rick.
Excellent advice and well described.
I bet you could do some permutation or another of that procedure to include more information... provided you had a specific hypothesis. |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 1317
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, June 23, 2013 - 10:20 am: |
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Just looking at the film images, it looks to me like a hinge leak .... but it's better to locate it precisely than to guess at it. |
Mattthegamer463
Tinkerer
Username: Mattthegamer463
Post Number: 5
Registered: 06-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, June 23, 2013 - 07:18 pm: |
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Hi guys,
I took a look at the camera and the foam near the hinge is pretty dead, and there isn't much metal doing any good light blocking there either, so I cut a piece of craft foam and just wedged it in there and closed the door.
I loaded up some film and went out to shoot a couple shots in the sun, exposing the camera to direct sunlight. I took a couple shots and held the camera in the sun a bunch, focusing on that hinge area. I also held the camera pointed in the direction of the sun with the aperture wide open for about 30 seconds on an unexposed frame.
I brought it home and opened the camera in my light bag, cut out the completed film and developed it. No leaks! There was just a tiny amount of exposure around one of the horizontal edges from the pointing at the sun.
I've never had a camera with a light leak issue (that I've noticed) before so I wasn't sure of the major spots for common leaks, so thanks very much for all the help guys. |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 1319
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, June 23, 2013 - 08:13 pm: |
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Excellent!
You've obviously never owned a Kiev - those are basically a light leak with a wind knob on top. |
Fidji
Tinkerer
Username: Fidji
Post Number: 47
Registered: 12-2011
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, June 24, 2013 - 05:24 am: |
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It's great you solved the problem.
I should have said the hinge side and not the catch side. Of course, the cassette is on the catch side on a Canon 7! Nice camera ! |
Hollenbj
Tinkerer
Username: Hollenbj
Post Number: 133
Registered: 03-2012
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, June 24, 2013 - 01:02 pm: |
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Ah, you have a Kiev Rick? You didn't mention that its usually worth tracking down those leaks. Truth be told, my Kiev 4 had few problems and still doesn't. That shutter will work long after I don't. |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 1320
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, June 24, 2013 - 08:30 pm: |
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Mechanically they've been fine, even the late 4AM (the f/1.8 Helios lens is also terrific), but the light leaks can be frustrating. Generally the light comes in the small RF window and down the sprocket shaft, and it's hard to plug up because of the moving parts along the way. |
