Canon FD shutters: leave cocked? uncocked? or doesn't matter?

[bsharpe411]

Since my very first SLR back in 1967, I've been told to always leave the shutter uncocked when storing the camera

for more than just a few hours. I've followed through on the rule (or is it old wives' tale?) with my FTb, F-1, A-1, and

EF, but I just realized that the T-90 shutter is always cocked, whether you like it or not. Am I missing something

obvious about how to store it uncocked, or is it just the way things are because of the integral motor drive? Another

thought just crossed my mind..."The dreaded EEEE". I've never experienced it with my T-90, but I understand it has to

do with the shutter locking up after sitting unfired for a long period of time. Is it just a coincidence? Or is there a

connection with the always-cocked shutter?

[richterjw]

Never having heard the rule before, I always leave my shutter cocked with no problems thus far. Maybe I should reconsider. However, with the "EEEEE," I have sometimes gotten that with my SSC breech lock lenses, but I don't think that's related to the shutter, at least in my case. Best, JR

[bsharpe411]

Thanx Jeremy....I've heard that the T-90 is part of the nightly ritual for some guys. (1) brush teeth (2) turn off light (3) kiss the wife and(4) fire the T-90 sitting on the night table. Happy wife...happy T-90

[daniel_kim7]

The rule is for A series canon manual bodies because they have the notorious shutter-squeal problem. As you store the camera with the shutter cocked, the shutter mechanism gets loosened. Therefore it is likely to develop the shutter squeal problem. Leaving it cocked for days is okay, but for months or years, you better release the shutter before you store it.

[User_4136860]

I Think The theory is that leaving the mechanism cocked , keeping the springs in tension weakens them, I try to fire my shutters before putting my cameras away, if I remember.

Daniel, I believe it's the mirror mechanism that squeaks not the shutter.

Bob,If only keeping the wife happy was that simple

[vincent_jan]

The old cameras you mentioned were spring-driven, and the idea was to leave the cameras uncocked in order to keep ensure that the springs were not stored under tension. Beginning with the AE-1, Canon cameras were equipped with magnetic shutters, meaning that spring tension was irrelevant, since there were no springs.

[bsharpe411]

Vincent. I'm certainly not a camera technician, or I'd already have the problem solved. But when you say "Canon cameras were equipped with magnetic shutters" the A-series cameras used magnets to release the shutter, but the magnets didn't actually push/pull the curtains across the frame opening. The power behind the curtain travel was springs. In the a-1 Repair Guide (page 170) there are a total of 7 different springs shown as part of the shutter mechanism.

 

As to why I have a repair guide? Well, every so often I start thinking I might be able to solve a camera-related problem myself. Then I look up the exploded diagrams in the guide and ask myself "What are you gonna do when you take off the cover and all that stuff DOES explode all over the floor?"

[ben_hutcherson]

With the T90, it doesn't make much difference. The springs that operate the shutter are under very little tension anyway, and as long as the shutter is closed at least one will always be under tension. The "lowest stress" position of the T90 shutter is when it's open.

 

Mechanical cameras like the FTb and F-1, however, are under a huge amount of stress when they're cocked, and comparatively little when uncocked. In fact, leaving one cocked for an extended length of time can cause the first curtain spring to weaken, leading to capping(premature closing) of the shutter at high speeds because the second curtain runs faster than the first curtain.

 

The same extends to the A-series cameras, as they use basically the same shutter design. The primary difference in the two is that the A-series cameras use electronics and magnets to hold the shutter open, rather than a clockwork timing mechanism.

[bsharpe411]

Ben H... Thanks for the advice. Each of my all-mechanical FD's have always been stored uncocked, but I wasn't too sure about the A-series and T-series procedure or need.

 

Ben M... I'd have a really happy wife if she saw all my cameras/lenses posted on Ebay. It's ain't gonna happen.