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jvuokko
31-Oct-2012, 07:07
Hi,


I did just some last time checks for my 4x5 wooden field camera before going on two month trip.. And noticed that there's some light leaks between the back (GG + film back assembly).
I used very bright flash light inside the camera and looked carefully for light leaks at my darkroom. The light is visible but very dim.

http://jukkavuokko.com/linkatut/lf/_DSC0342_light_leak_web.jpg



I haven't noticed this in negatives, but I guess it's something that must be sealed.


However, this makes me wonder that how light tight should these fittings be? The camera is worn and there's obviously some freeplay...

BrianShaw
31-Oct-2012, 07:22
That kind of gap would make me concerned too. I'm surprised it hasn't been noticable in your negs. Maybe you should look into adding a thin foam material to seal the gap.

Vaughn
31-Oct-2012, 07:31
Did you actually shine a light in the camera to see if light was coming through the gap? (One can check the bellows for pin holes at the same time). Keeping your darkcloth over the camera while the darkslide is pulled will reduce the chance of light striking the film from that area.

I have a light-leak problem in about the same area on my Zone VI 8x10 if the camera back is not lined up exactly centered (on the sides instead of the top). I should add extra baffles inside the camera.

Vaughn

jvuokko
31-Oct-2012, 08:19
I added some baffle, and now there's no light leak...

That's a good thing!


While checking if there's more small gaps where light can be seen, it took also the darkslide out from the film back that I used to block light coming out towards the ground glass.

To my big surprise (or shock), there was quite strong light visible from the dark slide's slot.
I checked some other film backs and every single has more or less similar light leak thru dark slide's slot.

These all film backs have been in my use long time. I have had occasional problems along the years, but nothing that I could trace down. This may be cause.

As I searched the forums, I found out that common solution seems to be simply to not to pull dark slide completely out for exposure, but leave it hanging on the film back.
That does not sound very useful as dark slide acts like a sail and I noticed also that the light leak is strongest when the dark slide is not pulled (fully) out.
During pulling/pushing dark slide to it's place the light may enter most freely to the film :O

John Kasaian
31-Oct-2012, 12:16
I'm in the practice of keeping the dark cloth over the whole thing when I'm shooting. It's cheap insurance.

Kirk Gittings
31-Oct-2012, 12:36
Wooden field cameras always light tight?
preferably.....

Leigh
31-Oct-2012, 14:20
I'm in the practice of keeping the dark cloth over the whole thing when I'm shooting. It's cheap insurance.
I do the same. It saves having to find a place to put the dark cloth where it won't get dirty. :D

- Leigh

jvuokko
31-Oct-2012, 14:56
I checked all my film backs.


12 of them has let more or less light thru the dark slide's slot. These all were film backs that I had tested couple of years ago with a unexposed film and opening the dark slide in bright sunny day and let film back sit on the camera 10-30 minutes. They passed my test successfully.

But not led flash light check :o


Only 9 were completely light tight. I could not see any light coming thru the dark slide slot.


There is not much common between leaky ones. The pile includes all my Linhof backs, several Lisco REGAL and REGAL II backs, some Fidelity Deluxe and Elites...


The light tight backs has more in common: Majority of them are Lisco REGAL II backs. Some are Fidelity Elites.


I haven't never opened any film back, so I don't really know how much there's done for fixing them. Perhaps dark cloth will do the job for those backs with some light leak...

jvuokko
2-Feb-2013, 08:21
I was couple of months trip, using only those 100% light tight film backs.


Now as I am back in home, the film back question is again my current intrest.
Should I open them and do something or just keep dark cloth wrapped around camera?

As so many of my 4x5 film backs let some light thru, this is probably very common issue.
I examined only by watching the dark slide's slot from outside, the back was attached to camera and I held bright against the film back but I assume that if light comes from inside out, it also goes from outside to inside :rolleyes:


I checked some of those film backs with dark slide pulled out but still attached to the back (like some LF photographers does). It was a surprise to see that hanging dark slide let more light come out from the film back's slot than completely removed dark slide.



I checked all my film backs.


12 of them has let more or less light thru the dark slide's slot. These all were film backs that I had tested couple of years ago with a unexposed film and opening the dark slide in bright sunny day and let film back sit on the camera 10-30 minutes. They passed my test successfully.

But not led flash light check :o


Only 9 were completely light tight. I could not see any light coming thru the dark slide slot.


There is not much common between leaky ones. The pile includes all my Linhof backs, several Lisco REGAL and REGAL II backs, some Fidelity Deluxe and Elites...


The light tight backs has more in common: Majority of them are Lisco REGAL II backs. Some are Fidelity Elites.


I haven't never opened any film back, so I don't really know how much there's done for fixing them. Perhaps dark cloth will do the job for those backs with some light leak...

Jac@stafford.net
2-Feb-2013, 09:30
There is a ridge behind that joint that keeps it light proof.

C. D. Keth
2-Feb-2013, 09:37
I checked some of those film backs with dark slide pulled out but still attached to the back (like some LF photographers does). It was a surprise to see that hanging dark slide let more light come out from the film back's slot than completely removed dark slide.

There is a light trap consisting of a spring and some velvet-like material that allows the darkslide to pass but closes behind it when the darkslide is pulled. The spring generally won't wear out but the black material will. I'm not certain of the best replacement but it can be disassembled and the light trap material replaced.

Peter Gomena
2-Feb-2013, 12:08
My whole plate camera's film holders are from the 1920s. I found that keeping the dark cloth over the back of the camera so that no direct light can strike the holders greatly improved my light leak problems. It's there from the time the holder goes into the back until the darkslide is reinserted. It's a bit of a pain, but worth it. I attach my dark cloth to the front part of the camera back with a couple of binder clips so it doesn't slide off.