Cocked shutter for over 6 hours may throw off calibrations!!??

[Augost]

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I recently read that having the shutter cocked for over 6 hours may throw off calibrations on my precious M?!!??

 

As I have always cocked my shutter right after taking a picture, this troubles me allot!

 

Does anyone know if this is true and what this does to the camera?

 

Also, I am guessing that this also regards other cameras than leicas???

 

Please help!

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[earleygallery]

What you read was rubbish as far as M cameras go. It doesn't really matter if you leave your shutter cocked or uncocked.

[Walt Calahan]

First I've heard of this.

[jaapv]

Where did you read that? Afaik that is nonsense.

[farnz]

If the way you normally shoot is to cock the shutter after taking a shot then it will be cocked when you put the camera away overnight - or longer - so you already know that it's not true because your precious M hasn't gone out of calibration.

 

Pete.

[Messsucherkamera]

I talked with Sherry Krauter about the cocked vs. uncocked shutter issue awhile back.

 

While she didn't say anything about the time a shutter is cocked between shots, she did say that you should always store your camera with the shutter in the uncocked position.

 

When the shutter is cocked, all the springs are under maximum tension. There's no point in putting a camera away in this condition. Leaving a camera cocked for days/weeks/months on end will cause the springs to take a set over time. This will weaken them.

 

Not good.

[skinnfell]

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You do not specify which M you own (presumably not the new M called just M).

However, analog film M cameras have a horisontal-travel shutter designed to be in force at all times. The force just moves from the left to the right curtain.

 

Some older film slrs had shutters that could be worn extra if they were cocked for a long time. (so the long time storage advise would apply)

 

I have alwats been told that it makes no difference at all wether you cock it or not.

 

It seems weird to me that someone like Ms. Krauter would give such an advice. Not that it does any harm to store it uncocked, its just that I have always been told that it does no harm to store it cocked either.

 

(However, a good leica man is always ready for the next decisive moment!)

[stunsworth]

When the shutter is cocked, all the springs are under maximum tension. There's no point in putting a camera away in this condition. Leaving a camera cocked for days/weeks/months on end will cause the springs to take a set over time. This will weaken them.

 

Not good.

 

Perhaps it depends on the camera. There's a quote on the net from the late Sal DiMarco who asked Leica the question in the seventies. Their reply was that uncocked the shutter springs are at 50% tension, cocked they're at 75%. Leica's advice was that it doesn't make any difference is the camera is stored with the shutter cocked or not.

[andybarton]

David Stephens always stores his second hand stock un-cocked, but that's just force of habit, I think.

 

It's not something I worry about. Leica shutters and the springs are designed for a lifetime of use and are more than strong enough not to worry about being cocked or not.

[wattsy]

Their reply was that uncocked the shutter springs are at 50% tension, cocked they're at 75%. Leica's advice was that it doesn't make any difference is the camera is stored with the shutter cocked or not.

 

Yes, I've heard that too. I remember a similar 'debate' when I owned a shotgun – should you dry fire (with snap caps) the gun before putting it away for storage or not. As with the argument here the answer depends upon who you talk to with the consensus (again like here) that, whether you store cocked or uncocked, it doesn't make any practical difference.

[TomB_tx]

Having designed springs for products for many years, an engineer always calculates and considers stress levels in a spring to be sure it doesn't take a set under the maximum operating load. A focal-plane shutter has enough room for a reasonable spring so that there is no reason to load it to high stress levels, and it would normally be designed to have low enough rate that the curtain speed wouldn't change greatly as it travels - so the stress wouldn't change greatly either. The stress levels when cocked should not be high enough to cause a problem in any case.

What I have seen on very old cameras is shutter curtain deterioration on whichever curtain is left "flat" across the film gate when in storage, especially if left on a shelf with that curtain exposed to light. That curtain stiffens more than the "rolled" curtain as the rubber coating ages faster. Usually this is the second curtain, because most cameras are stored un-cocked - but I've seen a couple that were clearly stored cocked. (Springs were fine, but the stiff curtains slow the shutter.)

[adan]

Keep in mind that virtually all cameras today have motorized shutter cocking (except the M7-MP) - so their shutters are ALWAYS cocked except at the moment of firing. If it were an issue, millions of cameras would be failing left and right. Even in the era of the Leica shutter design, motorized Nikon Fs and F2s were also always "cocked" - and were perhaps the most reliable cameras on earth.

 

I think in the old days of Compur or Seiko/Copal leaf shutters, there was some truth to the idea of not leaving those shutters cocked, and even that the shutter speed should only be changed when the shutter was uncocked. But that is a whole different mechanism, with smaller, lighter-built springs to fit inside a lens, and a lot of "gear-shifting" to move between the various shutter speed ranges.

 

And even that may be a myth - at the shop, we have 80-year-old Kodak box cameras with simple, Holga/Diana-type self-cocking spring shutters that are also always "cocked" except at the moment of exposure - and many of those are working as crisply as the day they were made, despite having sat "cocked" for 99.99999% of those 80 years.

[Jeff S]

The OP's initial question concerned "calibrations thrown off after shutter cocked more than 6 hours." Let's at least dismiss that notion.

 

IIRC, the manuals for some of my film Ms (M6 or M7?) recommended cocking the shutter and releasing at all shutter speeds at least every 3 months to keep lubricants from sticking. But that's another issue.

 

Jeff

[earleygallery]

And even that may be a myth - at the shop, we have 80-year-old Kodak box cameras with simple, Holga/Diana-type self-cocking spring shutters that are also always "cocked" except at the moment of exposure - and many of those are working as crisply as the day they were made, despite having sat "cocked" for 99.99999% of those 80 years.

 

Yes, I have some 100+ year old box cameras, I use them and follow the exposure guide of the day, adjusted to whatever ISO film I'm using. Calibration isn't off enough to spoil the images!

[Augost]

You do not specify which M you own (presumably not the new M called just M).

However, analog film M cameras have a horisontal-travel shutter designed to be in force at all times. The force just moves from the left to the right curtain.

 

Some older film slrs had shutters that could be worn extra if they were cocked for a long time. (so the long time storage advise would apply)

 

I have alwats been told that it makes no difference at all wether you cock it or not.

 

It seems weird to me that someone like Ms. Krauter would give such an advice. Not that it does any harm to store it uncocked, its just that I have always been told that it does no harm to store it cocked either.

 

(However, a good leica man is always ready for the next decisive moment!)

 

I have a few M's, all analog.

 

Thank you, this makes perfect sense, as the force always has to be in one of the spring.

 

This is exactly why I am asking, as I like to be prepared and able to capture spontanious shots.

[Augost]

Keep in mind that virtually all cameras today have motorized shutter cocking (except the M7-MP) - so their shutters are ALWAYS cocked except at the moment of firing. If it were an issue, millions of cameras would be failing left and right. Even in the era of the Leica shutter design, motorized Nikon Fs and F2s were also always "cocked" - and were perhaps the most reliable cameras on earth.

 

I think in the old days of Compur or Seiko/Copal leaf shutters, there was some truth to the idea of not leaving those shutters cocked, and even that the shutter speed should only be changed when the shutter was uncocked. But that is a whole different mechanism, with smaller, lighter-built springs to fit inside a lens, and a lot of "gear-shifting" to move between the various shutter speed ranges.

 

And even that may be a myth - at the shop, we have 80-year-old Kodak box cameras with simple, Holga/Diana-type self-cocking spring shutters that are also always "cocked" except at the moment of exposure - and many of those are working as crisply as the day they were made, despite having sat "cocked" for 99.99999% of those 80 years.

 

I do not use cameras with motorized shutter cocking. And stating that "Keep in mind that virtually all cameras today have motorized shutter cocking (except the M7-MP)" is completly wrong, seeing as the M3,M2,M1,M4,M5,CL,M4-2,M4-P,M6 and M6TTL do not have this. And those are just the Leica Ms...

 

Of course these are not new cameras, but the are still relevant, since my question was about Leica Ms.

 

I use an M6 and an M2 mostly.

[stunsworth]

I do not use cameras with motorized shutter cocking. And stating that "Keep in mind that virtually all cameras today have motorized shutter cocking (except the M7-MP)" is completly wrong, seeing as the M3,M2,M1,M4,M5,CL,M4-2,M4-P,M6 and M6TTL do not have this. And those are just the Leica Ms...

 

I assumed the earlier poster was referring to cameras that are available to be bought new. Appologies to them if this is incorrect.

 

Anyhow, you have your answer in the posts above, it doesn't make any difference.

[ho_co]

There's a quote on the net from the late Sal DiMarco who asked Leica the question in the seventies. Their reply was that uncocked the shutter springs are at 50% tension, cocked they're at 75%. Leica's advice was that it doesn't make any difference is the camera is stored with the shutter cocked or not.

 

Steve is right. When I worked for Leica, we were told the same thing but without the numbers: The shutter is never fully tensioned nor ever fully relaxed; the difference in tension between wound and not wound is 25%; it makes no difference whether the camera is stored cocked or not.

 

Or just using general knowledge: Leicas are pretty reliable over time; I've never heard someone say "Oh, this one's shutter isn't working right. It must have been stored cocked [or uncocked--take your pick]."

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Hallo,

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[stonearabiapix]

Just don't go around 1/2 cocked!

[philipus]

Some interesting reading in the M2 service manual, p 23 (troubleshooting) and p 50 onwards (adjusting shutter speeds).