Burned M6 Curtain

D

Dan Chang

Established
Local time
2:07 PM
Joined
Feb 19, 2005
Messages
109
This curtain was burned when the user fit the lens on and look throng the lens for a while under strong sunlight, the curtain is not burned through yet. Every focus plane shutter Rf user should know the rule. Canon User too
 
backalley photo said:
dan, i think my ss curtains are safe.
dontcha think?

joe
Click to expand...

sorta of better than cloth one
the plastic coating still can be burned. you trade durability for noise and age wrinkles....
 
somewhat true, but i don't remember the last time someone looked up or around when my p went click.
and my understanding is that the ss curtains need replacing much less often the most cloth curtains, but that's from reading only.

joe
 
Yes, I used a Nikon S2 once that had sat for quite a while in the camera shop's front window. Had half a dozen or so pinholes burnt right through the shutter.
 
How long does this kind of damage take on a standard issue sunny day? I often think about this when walking around with a 35 & vented hood and no cap that fits the hood. It's too easy to forget to cover up with a hand or the like and I can't stand having the front of the "eveready" case hanging around.

Is stopping down enough protection for most situations? Is there a cover that fits over the round vented hood and stays on in a stiff breeze? (I've lost a couple of elasticized bag covers to the wind.) What do you all do to safeguard the cloth curtain? I've tried dropping it back in the waist bag, but it's hard to be at the ready with your tools in the bag.
 
i would think that stopping down would make it worse. more pinpoint focussing of the lens on cloth.
from what i have read it does not take too long, a nice long car ride with the camera on the seat, in the sun, lens up.

yeah, seems like a design flaw...;)

joe
 
I'd agree with you Joe that this rates a fairly major oops. I suppose I'll just go on with looking for the perfect sock. It doesn't bother me with the 50 because I have the cap hanging there to remind me to cover up, but the 35 is a problem.
 
I followed a suggestion on an other site and use a generic 58mm snap on lens cap on the vented hood of a Summilux 35mm. Maybe you can find one to fit yours also.

Bob
 
I use a generic 58mm Snap On with my 8.5cm F2 Nikkor hood. Works well.

I always stop the lens down when walking around with cameras with cloth curtains. At F16 the lens lets in 1/64th of the light as it does at F2. That is a fairly dim spot. This would be a good experiment using some black fabric in place of the camera.

The cloth curtain Nikon SP is quieter than the Titanium Curtain version. Nikon chose cloth curtains for the SP-2005. The titanium curtains are durable, and do not wrinkle like the Canon plastic-coated steel curtains. However, the wrinkles make no difference in actual operation.
 
According to Roger Hicks, if you close down the lens the risk of burning a hole in the shutter curtains is significantly lower.

Now, if I'm walking around with the camera around my neck and a 35 lens with hood... I simply twist the camera so it points downwards.

In any case, from what I've read, curtain replacement is a $150 job at DAG. Good luck!
 
Also, focussing the lens at close distance will help a bit (since the sun is at infinity...)

Roman
 
This is an interesting topic that comes back often.

How long it takes? if it is well focused on the curtains, in a few seconds you can start melting the material. Black cloth is a very good absorber of light.

I'd agree with Roman, except: The shutter curtains are somewhat in front of the focal plane, obviously they cannot be exactly in the focal plane, that's reserved for something else. Thus if you focus just a bit closer than infinity, you might end up with a better focused little sun on the curtain.
As to stopping down, that will decrease the light that goes through the lens AND increase the focusing accuracy. Two things working against each other. So if the focus setting is as bad as possible, you better stop down since the spot is the smallest anyway. Otherwise, there can be indeed a case when stopping down a bit increases focusing accuracy on the curtains faster than decreasing the light intensity. Without a serious calculus, i couldn't say if this can ever happen or not.
 
After reading this thread (and posting), I fished out an old 58mm lens cap I had laying around (remnant of a Nikon lens sold a while ago).

It fits the lens hood of my Hexanon (which is, apparently, the same size of a Summilux 35/f1.4 even though it's only an f2). Guess where the lens cap is parked now?

As for the distance and focusing... I don't believe just carrying the camera around your neck will burn the curtains. It should be exposed, as joe said above, aiming to the sun, and motionless, like left inside a car, lens up looking at the sun. I walk with my camera and the lens uncapped. Of course, I close the aperture down and point downwards, but for me to damage the curtains I'd have to stand still, point the camera to the sun, and let the light work its power... for a while.

Some time ago, on a nice, sunny summer day, I took out both Leica-mount lenses (it was my 'cron and my Hexanon) and put them on the ground, on a piece of paper. I even aimed them at the sun... and still didn't burn the paper. Not even slightly warm. Mind you, both were wide open. If this happened to me while attempting to use the lens with "evil" purposes... :confused:

I guess it won't take a second to wreck the shutter curtains. :eek:

Life is full of paradoxes... :(
 
Last edited:
Stopping down will definitely help, since that means less light will hit the curtains. If you have a collapsible lense, retracting it will help too.

Best way to see how long, is to take a non-bottom loading LTM, put a piece of black tape across the film guide just as we would when checking infinity focus, set the shutter to bulb, open it up and point it up at the sun. We could even time how long it takes to start smoking, burn thru etc.

Maybe we can trade results... does a J8 burn as nicely as a Summicron :)
 
If you focus sunlight on a piece of paper using a magnifying glass -- to the smallest, most concentrated point possible -- it will burn a hole through the paper in less time than it takes to write this. It seem like the smaller the aperature the more likely you are to suffer damage to a cloth shutter. In any case, it ain;t going to happen unless the les is point almost directly into the sun. It's funny now hearing folks discuss it. There was a time when that was one of the first things a person with a focal plane shutter learned. Protecting the camera and lens from direct sunlight was just second nature.
 
Somewhere or another, relatively recently, I found a whole dissertation on this. Because of course I am paranoid about it - me being me I have to have something to worry about.
I can't find the link (of course) but I'll see if I can find it.
Upshot of it was, this bloke did some serious testing and found that yes, you could very easily burn thru the shutter curtains. BUT......the lens had to be wide open, and the camera had to be still, pointing into bright sun. He tried a lot of other combinations and none of them seemed to cause damage.
So his conclusion - on a bright day you are liable to ahve the lens stopped down anyway. And swinging around on a strap it will never be steady enough. But if you leave the camera facing up on a cafe table or a car seat then you could be in trouble.

It still doesn't stop me from being paranoid.

I'm gonna have to try and find that link now. brb......
 
You must log in or register to reply here.
Back
Top Bottom