Film holder light leaks

[michael_veit]

First, thanks to all for their answers to yesterday's "Residual developer" question. The darkening effect of hot water on that negative remains a mystery, but everyone's input was helpful and with some experimentation, maybe I can track the source down.

 

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Secondly, I have another basic question:

 

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When I started LF photography 8 months ago, I used to unload exposed film by completely removing the slide from the holder, removing the film and then storing the slide/holder seperately in dust free containers. About 3 months ago I started to only pull out the slide far enough to remove the film, and then re-seating the slide to store the slide/holders together. Easier, quicker, more elegant (and obvious -- but such discoveries take a while for me). Fine. Except that I shortly afterwards discovered that I was devoloping light leaks, particularly on the corners of negatives, on the side where the slide was removed during exposure. The only thing I can figure is that by storing empty holders with slides in place, the felt (I assume there's something like that) in the slot through which the slide moves is constantly in a compressed state except for the short time it takes to remove the slide and expose the film -- it never has a chance to uncompress and therefore stays compacted when the slide is out, causing light leaks. Is my theory a reasonable possibility? What is the dominant practice of holder/slide storage? Would not completely removing the slide during exposure help? Is there any other reason why I should be getting fogging on that side? All thoughts welcome, as this has become a real issue for me, with many shots ruined.

 

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Thanks,

 

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-Michael

[pete_andrews]

I don't know of anyone who pulls the slide and stores it separately

(well, until now that is).<br>Are the holders new? New filmholders

shouldn't suffer light leaks until they've had many years of use, or

hundreds of sheets of film through them. Some people pull the slide

out completely for exposure, and some leave it just nipped in the

holder. It seems to make very little difference. I doubt that the

filmholders themselves are at fault, especially if this occurs

regularly with a number of different DDs<p>Reasons for light leaks

that I can think of might be:<br>You might inadvertantly be lifting

the holder away from the camera back as you pull the slide or push it

back in.<br>You might have some dirt or grit in the rebate of the

camera back.<br>You might be trapping the film under the flap of the

DD, preventing it from closing properly, but this would give leaks

near the flap, not at the other end of the darkslide.<br>You might

even be flexing the slide as you push it back in, and forcing a gap

open in the light-trap.<br>I'd open and close the slides a lot more

slowly and gently, and see if the problem goes away.

[michael_veit]

Thanks, Pete. The only thing that's changed in my technique that I'm

aware of is the dark slide storage thing, but I'll certainly double

check those things you suggested. The holders are bought off of ebay

and presumably well aged, but worked fine for me to begin with. Very

strange and annoying.

[michael_veit]

I just took an offending holder into a dark room, and checked the

corners with a pen light and the slide removed. Bingo, there was a

pin-prick of light visible from the end. Putting the slide back in

part way seemed to help, although the slide may just have cut off the

correct angle of view for me. I'll definitely shoot with the slide

only partially removed from now on.

[scott_walton2]

Along with all the good tips that Pete stated, check your bellows for

pinholes and ungluing of the sides. It might be that you have a small

enough leeak that only shows up when light is directly on it.

Cheers

[scott_walton2]

Actually Michael, I would just get rid of the holder all together!

[michael_veit]

"I would just get rid of the holder all together!"

 

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If only the crap I produce during the typical shooting session

warranted such drastic measures! Only kidding, I'm slowly improving.

Thanks, I'm seriously considering new holders.

[tony_galt]

I'm new to this, but I've found that removing the slide completely during exposure allows me to you it as a handy lens shade.

[doug_paramore]

Michael: Many photographers drape the dark cloth over the rear of the

camera during exposure to avoid the problem you have. Direct sunlight

should not be allowed to hit the edge of the holder with the slide

removed. Also, try to make the exposure as soon as you can after

removing the slide and re-insert it immediately. If you remove the

slide and wait for that cloud to move to the exact spot you want it,

drape the cloth over the camera. Even new holders can leak if direct

sunlight shines on the end of the holder with the slide removed.

 

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Regards,

[rob_pietri3]

I have had similiar problems on occasion but here is my general

routine. I generally always have my film holders loaded and ready. I

have a small vacume cleaner and a brush attachment used ONLY for

photographic purposes, like cleaning my film holders after each used.

When loading, you have to make sure the film is in the channels and

pushed all the way forward so that it does not rest on that little

lip on the hinge end of the holder.

 

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When pulling and reinserting the slide to make an exposure, always

have your thumb or a finger on the back of the camera to keep the

pressure plate from moving. If your not careful, you can

inadvertently lift that plate and it only takes less then a

millimeter to cause some flare in the corners.

 

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Hope this helps.

[bill_youmans]

I agree with those who advise keeping pressure on the back plate

during slide removal. I used to keep the darkslide just barely

tucked in the holder slot during exposure, until a little bit of

breeze came along and turned the darkslide into a wind flap and,

well, I don't do that anymore.

[aaron2]

Hi Michael,

 

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Any fogging on the printed image or just light leakage on the film

edge? I happen to experience the same problem just now. Thanks,

 

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Aaron

[michael_veit]

Aaron,

 

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The problem is primarily in the corners and does sometimes extend

into the image area. Storing the slides seperately may have been a

crazy practice, but I'm convinced it helped stave off the problem

with these old holders.

[aaron2]

Thanks Michael. Appreciate it. Aaron

[reinhard_schwartz]

As an internet newcomer I was impressed about the variety of themes

in regard of large format photagraphy in this website.

 

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May be I can contribute to this discussion about filmholder light

leaks. I have had simular problems with my High Fidelity 13/18cm film

holders and now they are leakproofed.

 

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When I was reading this problem from Michael I must think about the

problem solving theory from Kepner Tregoe, which helped me a lot

during my professional life as a development engineer.

In short termes: Most important is thorough analysis at the beginning

and not to follow unorganized the first ideas or theories. To prevent

this some basic questions has to be answered. What is the problem and

what not? When it occurs and when not? Who has this problem and who

not? These questions seems to be obvious, but you can come to

conclusions, where you have normally not thought about.

In our case the questions must be:

Have all holders this problem? Shows a specific holder repeatable

leakeffects? Since when you have realized leaks? Have you only one

kind of leaks?......Such a carefull questinnaire helps to look not

only for one effect and then later to find others.

I have had some negatives from impressive motifs from a Iceland trip,

which were nearly waste, which forced me to analize the situation

afterwards (such tests we should make before or after a secondhand

business!).

My analysis guide me to the following leak sources:

 

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1. On used cameras check whether the elastic "light-sealing" of the

camera back (out of poyurethane, soft rubber or black velvet) is

still in good condition or may be is too porous, too much compressed

or shrinked. The problem is, that we normally cannot see these areas.

 

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2. Black areas on right or left bottom side of the negative were

caused in my case by aged platic tape, which is used as hinge for

the bottom lid. This material gets pervious for light by wear (can be

checked by holding agaist a small light source). I have sticked a new

black tape above the old and cut it thoroughly around the shape of

the bottom lid.

 

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3. I have found among my 10 film holders some, where the bottom lid

has shrinked (as it is a normal risk with elastomeres) and this has

caused two thin corner channels for light, if the slider is opened.

This can be reduced by the tape operation from 2. if the tape is

cutted exactly. Otherwise the film holder can only be thrown away.

 

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4. The same cause as in item 3. is the source for leakages right and

left on the top of the negative long side. There happens another

shrinking effect between the welded or glued plastic parts, which can

cause one or two light channels to the negative, if the slider is

opened. These channels (approx. 0.3/0.3 mm )can be closed by some

layers of black yarn and fixed with glue afterwards.

 

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Items 2. to 4. can occur only if the slider is open i.e. during the

exposure time. I have tested my holders although in closed position

with and without the slider and have not found any effect of

additional leaks. Therefore minimum in my case the light sealing of

the slider was not leaking, what is understandable because there is a

bronze double lipseal , which seems to be ok even after a long life.

(But on my Linhof rollfilm back this sealing is made out of rubber

and was after 20 years totally porous and was changed from me against

velvet).

 

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A very important hint was given from Pete Andrews in regard of the

necessity of care during lifting the slider because of the limited

springforce of the screenholder, which is reasonable for the contact

sealing in this area.

 

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So I hope my english is understanable enough to help a little bit in

this annoying theme.

 

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Good success Reinhard