The power of the sun...

[wolves3012]

Out of idle curiosity and having a piece of shutter-cloth left over from re-curtaining an RF, I decided on a semi-scientifiic experiment to see how easy it is to burn holes in a shutter curtain. We've many of us heard the stories and wondered if it can happen.

The short answer is YES, it can! Focussing the direct sun onto the cloth, with a 50mm f/2 lens, punched a hole almost instantly! This equates to pointing an RF (with fabric curtains) straight at the sun with the lens on infinity - not hard to do if you're careless.

A little more experimenting showed that at f/4 I was able to scorch the fabric after a few seconds but I couldn't hold the lens focus accurately enough to do more harm. Hold it still for a few seconds and it just might burn through. De-focussing wouldn't burn or scorch even at f/2, nor would a hazy sun.

Moral: use a lens-cap, de-focus the lens or keep it WELL stopped down if there's a chance of direct sun getting in the frame!

 

[newspaperguy]

Wolves - You have sunshine? 😀

 

[ferider]

Actually, de-focus might be worse, since the shutter cloth is in front of the film. Infinity might be safer 🙂

Cheers,

Roland.

 

[furcafe]

It indeed does happen. It should be intuitive to anyone who remembers playing w/a magnifying glass as a child, but I was still a little surprised when it happened to my M7 2 summers ago. I still don't use lens caps, but have learned to de-focus or be more careful of where my lens is pointing when the sun is bright. Or I'll use a camera w/a metal shutter!

Out of idle curiosity and having a piece of shutter-cloth left over from re-curtaining an RF, I decided on a semi-scientifiic experiment to see how easy it is to burn holes in a shutter curtain. We've many of us heard the stories and wondered if it can happen.

The short answer is YES, it can! Focussing the direct sun onto the cloth, with a 50mm f/2 lens, punched a hole almost instantly! This equates to pointing an RF (with fabric curtains) straight at the sun with the lens on infinity - not hard to do if you're careless.

A little more experimenting showed that at f/4 I was able to scorch the fabric after a few seconds but I couldn't hold the lens focus accurately enough to do more harm. Hold it still for a few seconds and it just might burn through. De-focussing wouldn't burn or scorch even at f/2, nor would a hazy sun.

Moral: use a lens-cap, de-focus the lens or keep it WELL stopped down if there's a chance of direct sun getting in the frame!

 

[brachal]

It definitely happens. Happened to my Fed-3 a couple of years ago.

 

[Photon42]

Actually, de-focus might be worse, since the shutter cloth is in front of the film. Infinity might be safer 🙂

Cheers,

Roland.

That was my first thought, too.

 

[uhligfd]

How about metal shutters such as on the Bessas, Contax G etc: any harm from sun focusing on the blades?

Or will it just take longer until the film behind the shutter blades catches fire? And holy smoke goes up?

 

[ItsReallyDarren]

That's gotta be some slow film to use f/2 in sunlight.

But seriously, that's some handy information to know. How about f stops past f/4? Would the aperture be so small, say around f/8 that burning a hole is no longer a concern?

 

[Sam N]

How about metal shutters such as on the Bessas, Contax G etc: any harm from sun focusing on the blades?

Or will it just take longer until the film behind the shutter blades catches fire? And holy smoke goes up?

Modern film isn't flammable like old movie film, and the metal shutter wouldn't heat up enough anyway.

Safest choice : leaf shutters 😛

 

[David Murphy]

The heat can damage you lens and camera too, so I'd not try this on anything that you want to keep. It can probably set the camera on fire if exposed long enough especially if there are plastics or stray lubricants. I know of other optical focusing instruments that suffered this fate due to inadvertant Sun exposure.

 

[Al Kaplan]

I usually carry cameras over my shoulder, not around my neck, and I turn it around so the lens faces my body.

 

[wolves3012]

Wolves - You have sunshine? 😀

Oh yes, been a gorgeous week here!

 

[wolves3012]

Actually, de-focus might be worse, since the shutter cloth is in front of the film. Infinity might be safer 🙂

Cheers,

Roland.

I meant de-focus a LOT, good point though!

 

[wolves3012]

How about metal shutters such as on the Bessas, Contax G etc: any harm from sun focusing on the blades?

Or will it just take longer until the film behind the shutter blades catches fire? And holy smoke goes up?

Eventually things could get hot enough to cause problems elsewhere but (most) metals don't burn and you won't melt them with a camera lens.

 

[wolves3012]

That's gotta be some slow film to use f/2 in sunlight.

But seriously, that's some handy information to know. How about f stops past f/4? Would the aperture be so small, say around f/8 that burning a hole is no longer a concern?

If I couldn't do worse than scorch it at f/4 then f/8 ought to be safe unless you leave it sitting. I don't recommed you try it with a camera though!

 

[mooge]

I was fortunate enough to borrow a friend's M4-P and was deathly afraid of burning the curtain. I'd stop down to f/16 every time the sun was vaguely in the frame, and I'd avoid that at all costs almost. heck, if the lens cap was off (and I left it off- the hood goes on. coolest thing ever, by the way, that summicron 35 and hood...) and the sun was out, I'd leave it at f/16 AND tuck it under my arm with my wrist over the lens. yeah. paranoia. well, the deal was that he would kill me if I broke it!

uh, but what about sunsets/sunrises? I did a few of those with the sun in the frame and didn't get any burns- is it much less risky than the midday sun?

 

[furcafe]

I think it depends on where you are & the time of day; both affect the sun's intensity. When I scorched the curtains on my M7, it was about an hour before sunset on the beach @ Coney Island in NYC & probably took longer than it would have a few hours earlier, but it still happened.

uh, but what about sunsets/sunrises? I did a few of those with the sun in the frame and didn't get any burns- is it much less risky than the midday sun?