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Help Diagnose a Canon F1n light leak

saambaam

Member
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Jan 2, 2018
Messages
6
Location
Brooklyn
Format
35mm
I'm trying to diagnose some issues with my Canon F1n. There are a couple oddities going on. First - when using my top shutter speed (1/2000) I sometimes get one vertical band of increased density near one edge - must be an issue with the shutter's movement that gets exaggerated on the negative at very high speeds. I had a similar issue about a year ago with half of my frames starting to get dim, and then totally black, but the issue was fixed with a CLA. Given that I'm having another issue with the shutter, should I abandon hope with this body and get another one instead of investing in yet another CLA? I've probably put ~100 rolls of film through the camera since that CLA.

The other is harder for me to wrap my head around. The corners of some frames have increased density. It has occurred with at least two different lenses, and at very different shutter speeds. Here are some examples:

800 speed film, probably ~1/30 or 1/60: https://imgur.com/a/zSKVt
800 speed film, probably ~1/500 or 1/1000: https://imgur.com/a/ndDJU

It's started to get worse - on one frame in a recent roll, almost the entire frame is overexposed, with an emphasis on the bottom right corner. What could cause this?

Thanks for any help.
 
Certainly sounds like shutter drag! You might have something like old foam from a light seal dropping down into the shutter channel. Were the light seals replaced? Is there any sign of deterioration of the light seals?

As for the photos; the 2nd image looks like internal light flare from not having a lens shade, as the sun appears to be coming from the upper left of the image but the first is more mysterious.

Did you use the same lens for both posted photos? You might have some internal contamination of a lens element that only shows up in certain situations...
 
Lens off, back open, shutter locked open on B, inspect the shutter track for debris. Lower right in the photo is top left in the film plane.
Shutter may be sticking open at the top while moving at the bottom for the last 1/4 frame or have a hole at the first to second curtain seal.
 
Probably shutter bounce - a common problem on F1n's. The shutter goes through it's cycle, then the 2nd curtain bounces back open giving a dark edge to the frame. Also happens with FTb's etc. Only fix is to replace the shutter brakes
 
The leak is on the bottom right of the nagative/print, therefore the leak is on the top left of the camera back or top right of the lens [looking at the front].
 
Sirius Glass said:
The leak is on the bottom right of the nagative/print, therefore the leak is on the top left of the camera back or top right of the lens [looking at the front].
Click to expand...
Ooh. I'm wrong. But changing the light seals will probably fix the issue.
 
Thanks for the help, everyone. It's definitely not a camera-back seal - these leaks do not extend to the edge of the negative, just to the edge of the frame. So whatever it is is coming through the mirror box.

I had all the foams replaced a year ago, and the problem is intermittent, so I'd think it's unlikely that the issue is a seal issue, even on the mirror side of things, though I could be wrong on that.

I could have sworn that these two images were taken with different lenses, but I may be mistaken. I'll look through my negatives again and see if the issue might be limited to one lens. The haze hypothesis could be correct here. I welcome any other input!
 
There are two vids over on Youtube showing how to adjust shutter timing for the Canon F1n .I have three F1n s and when i got them all needed the shutter adjustment at top speeds .It is not a bit job but care must be taken .Make a note of where the adjusters are and only make small adjustments at a time .The shutter brakes can also cause this problem but i have never come across it being the brakes
 

Found this video:


But - how will I know if I've done the correct repair (which direction, if I fixed the capping, etc.) if I don't have a method of checking the shutter speed? Will I just need to run a roll through and see if it helps? I imagine this repair could impact other shutter speeds too - any way to make sure I don't make the problem worse?
 
It is anti clock to increase tension /speed up / the shutter speed .The only way to find out if you have fixed the problem is to put a film through. Do not move the adjusters more than 1/4 of a turn at a time .Without the use of expensive shutter speed timers it is just a case of try and see . Adjusting the shutters alters all the speeds IE one of my F1n s wasnt working on the slower speeds i adjusted the shutter for top speed and they started working .
 
Changing the curtain tension is pointless unless the shutter has been cleaned and properly lubricated beforehand. You'll be increasing tension to compensate for dirt and poor lubrication, speeds will not remain stable and wear will accelerate. Have the camera properly overhauled.
 
The guy says he had it CLA just a year ago unless he has been keeping mice or livestock inside the F1 it should still be good
 
colin wells said:
The guy says he had it CLA just a year ago unless he has been keeping mice or livestock inside the F1 it should still be good
Click to expand...

Exactly. Unless the camera tech is a crook.

I wouldn't touch the curtain tension adjustment, ever! I already did on other two cameras and never got to make them work correctly. Also, this is a Canon F-1, a masterpiwce camera! Shutter is indestructible, unless it saw very very harsh use.
 

+1 what he says!!
 
colin wells said:
The guy says he had it CLA just a year ago unless he has been keeping mice or livestock inside the F1 it should still be good
Click to expand...
Exactly. Should.
But I've seen what often passes for "cla", which is why I will not buy a camera advertised as "cla'd".
I did a real cla on my Nikon F in February 1998, it is just now beginning to go sluggish in the cold, below about 20f. I have yet to readjust the curtain tension on it, either.
 
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