Shutter care

[Nigels]

Two items of good practice. Can anyone confirm that these are good practice and any insight as to why;
1. A shutter should be left uncocked and at its slowest speed or B or T if not in use for any length of time.
2. The shutter speed should not be changed whilst in a cocked state.
Thanks for any advice.

[David A. Goldfarb]

1. Some shutters engage an additional spring at the highest one or two speeds, and that might put some extra stress on the mechanism, so it's probably a good idea not to store a leaf shutter set at the top speed, but other than that I don't see a problem.

2. Some older shutters shouldn't be adjusted when cocked (it's possible to mess up the B & T settings on an Ilex shutter this way, for instance), but this isn't a problem with modern Copal shutters.

[Glenn Thoreson]

Your ideas are good practice. In addition, some old shutters have quirks of their own. Dial set Compurs, for instance, can be damaged by setting to top speed while cocked. I never change speeds while the shutter is cocked, regardless of age or make. Some of the Old Compurs, especially the dial sets, must not be cocked to use B & T. There are others of this nature, too. Many get broken due to ignorance and a ham fist. Treat your shutters like a fine time piece and they will repay you many times over.

[Turner Reich]

The aperature should be stored in the open position or the aperature should be stored stopped down. The blades will be oild free if stored stopped down.

Never coil up a cable release, store/keep them straight.

[Tony Karnezis]

http://www.largeformatphotography.info/forum/showthread.php?t=4657&highlight=lenses+shipped

A previous thread has addressed your first point. To quote two notable contributors:

"Springs used within their design elastic limits do not "know" whether they are stretched, relaxed or compressed. It makes no difference. So, the best option is one in which the iris and shutter blades are opened so as to avoid accidental mechanical damage." -Steve Grimes

"Brand new, factory fresh, lenses from Rodenstock are shipped in a standard unsealed plastic bag with a dessicant pouch in the bag. The Copal shutter is uncocked and set to "T" and the aperture setting is wide open." -Bob Salomon, HP Marketing

As for the "why" part of your question:

"A slight correction to Steve Grimes point about springs. While a shutter spring may be within its 'elastic' limit for both the cocked and un-cocked shutter, it certainly does 'know' whether it is stretched or not. In the stretched case, there is more elastic stress in the spring (that is spring energy), proportional to the square of the difference in the displacements from a fully relaxed spring. More to the point, what Steve is getting at is that within this elastic regime, the 'deformation' of the spring is not significantly different when the shutter is cocked or not." -Richars S. Ross

Others have addressed your second point--it depends on the shutter. As others have stated, some shutters can be damaged in some circumstances. I think I have a shutter that Glenn describes: when getting my 165 Super Angulon in a Compur shutter CLA'd, I was told it would suffer serious damage if set to its top shutter speed while cocked. Good to know...

[GPS]

Not to forget one of the best care - using the shutter from time to time! Makes miracles in the long term.

[Carsten Wolff]

http://www.flutotscamerarepair.com/Tips.htm

basically says it.