Always put lens cap on: Question re: light leak

[Hjortsberg]

M6 developed a light leak. Took it to well known/highly rated Leica repair shop in Los Angeles. Pin spot had developed in film curtain (I think that is the terminology for it)

I was told this will happen if you don't put lens cap on, lens acts as a magnifying glass and makes pin holes in film curtain leading to light leaks.

was told to always put lens cap on in-between pictures to avoid this problem. take lens cap off right before I take photo, I was told.

How do you shoot street photography if you are always to have lens cap on except right before photo?

Am I mis-understanding what the Leica repair guy said?

Thanks in advance,

 

[benmacphoto]

How do you shoot street photography if you are always to have lens cap on except right before photo?

Am I mis-understanding what the Leica repair guy said?

I never have a lens cap on while my camera is out.
I hold the camera so it doesn't face the sun while walking around.

Maybe mis understanding what the repair guy said, or they didn't explain it that well.
Just be mindful of where your camera is pointed.

 

[DNG]

You can also just put the palm of hand over the lens....That is what I do, even though I use an X100T or Nikon SLR.... made a habit a while ago when I did shoot RF's

 

[rick oleson]

It can certainly do that. An f/2 lens is a powerful little solar furnace, and if the lens is aimed at the sun it can burn a hole through the shutter curtain. This is not a theoretical exercise, I have proof:
https://www.flickr.com/photos/26262745@N08/15557039378/in/photolist-pGHTNS
This was an Exakta that I had lying on its back on the passenger seat of my car as I drove home for about 45 minutes. The shutter was released so the mirror was up, and the lens was set at f/2. You could see worm tracks all over the front of the curtain where the beam had moved as the car turned different directions, but it was going in a straight line long enough to burn through the shutter curtain and very nearly melt through the film. I managed to repair this with a little circle of film-changing bag fabric cut out with a paper punch and glued over the hole in the curtain.

With a Leica, if your lens is collapsible you can do that to put the beam out of focus when not in use, or you can stop the lens down, if you don't want to use a lens cap. All of my (cloth shutter) cameras, if they are on a shelf that can be exposed to the sun, now have the lenses stopped down to f/16 at all times when on the shelf.

(PS: this damage is not instantaneous. It happens when the lens is aimed so that the direct rays of the sun focus on the shutter curtain, and it takes a little time for it to damage the curtain. Normally carrying the camera with the lens uncovered as you walk, it is not likely for this to happen... but you don't want to set it down on its back while you have a picnic in the sun.)

 

[Hjortsberg]

Why doesn't the light leak show up in every photo of the 36 exp?

It only shows up in some of them.

 

[ferider]

It happens.

Easy to patch with "liquid rubber".

Hold the camera lens down, or shade it with your hand. Most dangerous when wide open and at closer focus (less risky when lens is at infinity).

Roland.

 

[rick oleson]

It depends on how much light was shining on the hole between exposures. If the hole is in the opening curtain it will leak while the shutter is cocked, if in the closing curtain it will leak when it's released. If you spend a lot of time in the sun between shots it will have a long time to leak light, if you shoot several shots in succession it will leak less because the exposure time is shorter. It will leak more if you carry the camera outdoors between shots than if you shoot the whole roll indoors in one sitting. Many variables, but all come down to that old photography thing - exposure time.

 

[dtcls100]

If you turn the focusing ring away from infinity to a close focus distance, there shouldn't be a need to keep a lens cap on. What you want to avoid is having the sunlight focused on the shutter curtain. Turning the focusing ring to near its minimum focus distance will help make sure that the sun is not focused on your shutter curtain.

 

[Sarcophilus Harrisii]

I use a Contax. No lens cap. No problem!
According to Roger Hicks stopping down one's lens on a Leica should help. In the absence of a cap if I had to use a Leica I'd try this.
Cheers
Brett

 

[jonmanjiro]

Most dangerous when wide open and at closer focus (less risky when lens is at infinity).

If you turn the focusing ring away from infinity to a close focus distance, there shouldn't be a need to keep a lens cap on.

Interesting! Should we set the lens to infinity or a close focus distance guys? 😕

In bright sun, when not shooting I tend to leave the focus distance set to a few meters and the lens stopped down, but naturally I've never actually tested whether or not this reduces the risk of burning a hole in the shutter curtain. Maybe I've been doing it wrong all along and just didn't know it...

 

[jojoman2]

I've never had this problem but I haven't been photographing long.. I'll stop the lens down if it's really bright and I'm not taking pictures and point the camera away from the sun when walking around. I'd sooner pay for new curtains once in a while than leave a cap on between pictures

 

[Robert Lai]

I would think that you need to defocus the sun to minimize the impact of the rays. The defocused rays would spread out over a wider surface area. You achieve this with the minimum focus setting on the lens.

Focusing at infinity would focus the sun's rays into a point onto the curtains. Since the shutter curtains are only a few millimeters away from the film plane, the lens focused at infinity is effectively focused on the shutter curtains too. As the sun is several billion miles away, it is the very definition of a subject at infinity.

You'll easily notice this if you experiment with a magnifying glass and a sheet of paper on a sunny day - just as we used to do in the schoolyard at recess.

I have habitually learned to point the lens down towards the ground if I am walking around uncapped outdoors.

 

[David Hughes]

Hi,

Over time pinholes might develop and the light coming through the lens on to them will fall on the film and you'll get a light blur there.

Keeping the lens cap on stops the light getting there and so on to the film.

The longer the 'exposure' the brighter the blurred spot. So firing several times quickly means no spot due to the short time the film is exposed. A pin hole acts like a f/512 aperture, or some figure and long time exposures are needed for the blob.

Several have mentioned temporary repairs, if you can find the pinhole.

Regards, David

 

[rick oleson]

Interesting! Should we set the lens to infinity or a close focus distance guys? 😕

Infinity (or near infinity) is the WORST CASE. That is where the rays from the sun are focused down to the smallest spot on the film.

Since the curtain is actually a mm or two forward from the film plane, the worst case for the curtain is when the lens is a little forward from the infinity stop (just how much depends on the camera design) ... so setting a closer distance might not help as much as you'd hope. If you rack the lens all the way to the close focus stop it should help. Stopping it down is better still; and if it's a collapsible lens, collapsing it will make it much safer.

Several have mentioned temporary repairs, if you can find the pinhole.

Regards, David

Finding the hole in the shutter should be easy: if it's caused by the sun there should be visible damage around the hole on the front of the curtain. To find a hole that's too small to see, remove the lens, open the back door and go into a dark room with a strobe. Looking in from the back, place the strobe head into the lens opening (make sure none of it is aimed at your eyes around the edge of the camera) and fire it. Any holes in the curtain, however small, will be instantly visible. Do this both with the shutter wound and released to inspect both curtains.

 

[ferider]

If you turn the focusing ring away from infinity to a close focus distance, there shouldn't be a need to keep a lens cap on. What you want to avoid is having the sunlight focused on the shutter curtain. Turning the focusing ring to near its minimum focus distance will help make sure that the sun is not focused on your shutter curtain.

Careful, see below !

Since the curtain is actually a mm or two forward from the film plane, the worst case for the curtain is when the lens is a little forward from the infinity stop (just how much depends on the camera design) ... so setting a closer distance might not help as much as you'd hope. If you rack the lens all the way to the close focus stop it should help.

This depends on the focal length of course. For a 35mm Leica lens, and a curtains to film distance of 1-2mm, anything below 1.3m focus distance is the most dangerous (647 to 1260mm, to be exact).

Having a 35mm or wider lens at infinity, and stopped down to f8 or more, is actually pretty safe. Just don't point it into the sun for too long.

Roland.

 

[David Hughes]

Hi,

Any and all light coming in through the lens, focussed or not and open or shut aperture blades will get to the pin hole and on to the film. Carrying the camera around without a cap on it means the time between shots is the exposure time. And if the camera is moving around when you carry it then the light will be all over the blinds. Imagine a pinhole camera with an exposure time in minutes or hours...

As for sun burnt blinds, they are few and far between. There was a survey some time ago on RFF.

Regards, David

 

[Highway 61]

It also depends on the material of the shutter curtains used on our old mirrorless RF cameras. Of course the Contax brass blades curtains, the Canon steel foil curtains and the late Nikon titanium foil curtains can't get burnt through by the image of the sun focused on them.

Yet it seems, given the very few examples of Nikon RF cloth curtains now wearing some fixed pinholes (while there are lots of Leica bodies wearing shutter curtains patches out there), that Nikon's special "habutae silk" was more resistant to this than the regular Leica fabric covered with a layer of rubber on the curtains backside to make them light tight.

 

[Dwig]

Infinity (or near infinity) is the WORST CASE. That is where the rays from the sun are focused down to the smallest spot on the film.

Since the curtain is actually a mm or two forward from the film plane, the worst case for the curtain is when the lens is a little forward from the infinity stop (just how much depends on the camera design) ... so setting a closer distance might not help as much as you'd hope. ...

Yep. With 50mm lenses and longer, setting the closest distance would be of significant benefit. With wider lenses, focusing closer can help much and may well make matters worse than setting infinity.

One thing that I used to do, back in the day of using RFs with FP shutters, was to carry the camera "backwards". I'd put the strap on my shoulder with the lens facing my body. I usually kept the lens capped, but on occasion I make a few shots without capping the lens.

 

[David Hughes]

Hi,

I am going to try and find some old blind material and see if I can burn it and time it and so on. The only blind I've seen with pin holes looked OK when bought...

Regards, David

 

[AndersG]

With some sun and a bit of time you can get notable results: When "baking"[*] my Jupiter 11 135mm f/4 lens in the autumn sun some years ago I melted a hole in the rear lens cap (a plastic film canister lid) even though it must have been quite far (~10mm?) from the film plane (I don't recall the focus distance set). I won't be doing that again.. 🙂

[*] Supposedly good for killing off fungus, but must be rather hard on the lubricants in the lens, I guess.