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Wiredbarbarian
Tinkerer
Username: Wiredbarbarian
Post Number: 3
Registered: 02-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 08, 2009 - 11:46 pm: | 
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Every time i load a film into my Petri rangefinder, it gets to about 15 exposures when suddenly i start hearing a slight "crunch" sound met with a bit of resistance.. turns out that after about 15 exposures its no longer wrapping the film around the spool but folding it up like an accordion instead. Its tearing up the holes in the film!
Anybody know what I can do to correct this? Someone told me it could just be that the camera is sensitive to cold/hot temperatures and that I shouldnt operate it outside in the cold, or at least wait a while for its temperature to stabilize. Anyone have a clue?
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Glenn
Tinkerer
Username: Glenn
Post Number: 514
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 09, 2009 - 08:58 am: |
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Forget about mythical rubbish such as temperature sensitivity, the problem is with the take-up spool. There are two possibilities - the take-up spool is becoming jammed or it is slipping, from the evidence I would suggest it is slipping. On loading the film the sprockets transport the film into the space around the take-up spool, but because the spool is slipping film will not be wound tightly onto the spool and eventually the free space will be full (at about 15 frames worth of film) The sprockets will still try and push more film into the space - hence the folding and eventual sprocket hole tearing.
You should be able to check if the above is correct fairly easily, if you are prepared to sacrifice a film. Load a cassette of film and instead of closing the camera back, use a finger or thumb in place of the pressure plate to tension the film. Now keep winding on the film and observe what happens at the take-up spool, you will not replicate the exact failure because the film will be able to feed into free air; however, you will see the film start to fill up the space very loosely instead of winding tightly around the spool.
I am unable to give you any details of how to clean or repair your camera, I have never worked on the Petri. |
Wiredbarbarian
Tinkerer
Username: Wiredbarbarian
Post Number: 4
Registered: 02-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 09, 2009 - 12:26 pm: |
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Thanks for the information! I will try doing exactly that as soon as I find an old film or something cheap lying around. Another thing I noticed, when it gets close to around that time, there is a delay in the shutter. The aperature opens alot slower and then closes after a delay...not always though, this behaviour seems to be at random.
When the camera isnt loaded with film, i try playing with different shutter speeds... sometimes the first time speed is fired, there is a delay, and then the other times it is correct.
Could this just be the lube that needs to get flowing after over 30 years of inactivity? (camera is from 1966). The shutter is not coupled to the advance lever. Should I just run it over and over until it starts acting more predictably? |
Glenn
Tinkerer
Username: Glenn
Post Number: 515
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 09, 2009 - 04:26 pm: |
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I am a firm believer that inactivity is a serious problem in all types of old equipment, cameras included. I would always try a bit of sensible exercise in a case like this; however, after 30 years the camera is probably crying out for a CLA, especially if you foresee regular future use. |
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