Canon LTM Canon P questions

Canon M39 M39 screw mount bodies/lenses
ampguy

ampguy

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What's the deal with the wrinkly shutter curtains? Are they an issue? Is a P without wrinkles worth more?

Are the later s/n ones much different? Dante's page indicates later ones were built on their own frames, while earlier s/n ones were built on previous model frames?
 
I absolutely love my two Canon P's. I have heard a couple of different explanations for the wrinkling but both of them sound more like urban legend. I think the only people qualified to give a really good answer are the Canon engineers that designed the thing.

I'm also a metallurgist and my personal theory is this: The shutter curtains on a P are supposed to be made of stainless steel. Most stainless steels have a fairly low yield strength, but they are also capable of deforming a lot and actually get stronger as they are deformed. I think the curtains are simply overstressed, and that the stress causing the dimpling comes from inertial compressive stresses when the shutter stops moving. In a very thin highly stressed foil, high compressive stresses cause buckling (think of what happens when you step on an aluminum pop can). What does this mean for the longevity of your Canon P? My theory is that eventually, afer a very long life of very heavy use, the alternate tension and compressive stresses will cause tiny fatigue cracks around the dimples. I'm not worried though because metal fatigue is normally measured in hundreds of thousands or even millions of stress cycles. I don't think either me or subsequent owners will take that many photos.

Enjoy your Canon P.
 
Thanks all, great info. So do the wrinkles come about from normal use, or is it people sticking their fingers in it?

I'm glad that whether wrinkled or not, they still work well.
 
ampguy said:
Thanks all, great info. So do the wrinkles come about from normal use, or is it people sticking their fingers in it?

I'm glad that whether wrinkled or not, they still work well.
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My repair guy says they come from contact with a finger, film canister, or some-such during film loading or when dusting out the camera or maybe even clumsiness during a CLA. (He then told me about mortal damage he accidentally inflicted on a Nikon titanium foil shutter.)


Steve
 
My repair guy says they come from contact with a finger, film canister, or some-such during film loading or when dusting out the camera or maybe even clumsiness during a CLA.
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Could be, but these wrinkles seem so common with the P, and not with another that I know of, that they could likely have something to do with the design. I have seen a lot of Canon F1 camera over the years, but rarely with a wrinkled shutter curtain.
 
Regarding the camera's chassis, Dechert mentions, in his book, that there were a few tweaks in the Canon VI that eventually made its way into the P (both the VI and P are based on the same chassis).

As for shutter wrinkling, the stainless steel curtains in the P are only 18/1000mm thick so it doesn't take much pressure to dent or wrinkle them. For what it's worth, I have an old Canon 7, with stainless steel curtains, that after 40 years of use, are in perfect shape.

Jim B.
 
I have never touched the shutter curtains of any camera I've owned, other than lightly with a lens brush to remove dust. I could understand a repair person damaging a shutter curtain during a CLA, but by all accounts virtually every Canon P has curtain wrinkling; so damage just doesn't make sense. It has to be something to do with the camera design.
 
hmm, lots of interesting info. From what I understand, there was a body frame change, but I don't know at what s/n change for the P to have it's own frame.

Not all have wrinkles, in fact you can buy one on ebay right now for cheap without wrinkles (but a bunch of small external dents).

I cannot imagine a design where a visible component was designed to be smunched up after normal use, but anything is possible I guess. So would that mean the few ones that *aren't wrinkled* may be defective?? ;)
 
I think it's obviously a design issue. Way too many wrinkled curtains out there to be general clumsiness.

Another "P" Question. I am thinking about picking one of these up.

Many seem to have "squeaky" advance mechanisms, which obviously need some oil. Is that all there is to it, or does it require a more expensive repair? Many of KEH's P's are notated to have the squeaky advance, so this seems to me like part of a good CLA. Am I missing anything here?

Thanks!

-Dan, presently converting from Leica M's to Rangefinder Canons and multiple Sony Nex-3's.
 
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Nokton48 said:
......Another "P" Question. I am thinking about picking one of these up.......
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Not to throw cold water on your quest for a Canon P, but make sure you look through the viewfinder of one before buying. Dechert states that the years haven't been kind to the viewfinder of the P and, in many cases, he's right. One that I bought years ago (sight unseen) was very flary and washed out. I quickly sold it, at a loss.

Jim B.
 
Hey Makinaw,

Thanks for that. So I guess I should inspect any "P" bodies I go for, before I go for them. The best way to be sure.

As I now have a nice VT, nice CLA'ed 7, and now a 7s (coming from KEH, needs overhaul) I am probably set for now, anyway.

-Dan


Mackinaw said:
Not to throw cold water on your quest for a Canon P, but make sure you look through the viewfinder of one before buying. Dechert states that the years haven't been kind to the viewfinder of the P and, in many cases, he's right. One that I bought years ago (sight unseen) was very flary and washed out. I quickly sold it, at a loss.

Jim B.
Click to expand...
 
Mackinaw said:
Not to throw cold water on your quest for a Canon P, but make sure you look through the viewfinder of one before buying. Dechert states that the years haven't been kind to the viewfinder of the P and, in many cases, he's right. One that I bought years ago (sight unseen) was very flary and washed out. I quickly sold it, at a loss.

Jim B.
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Definitely check the gold/ yellow RF patch! Many have faded. If it's faded, it's unusable. The wrinkled curtains are a non-issue to me.
 
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