Black spots on 4x5 negatives: darkslide light leaks?

Photopathe

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Hi! I am a beginner with large format (4x5). I have those black spots on a couple of negatives (white on prints and scans). Mostly on one negative and a little bit on a second one. They seem to appear in the same general area in both cases. I developped about 10 negatives before these and it didn't happen before. In one instance (the picture of the plant, included here) I took the same picture twice in the exact same conditions with a flash and without moving the camera. One of the picture has the spots the other doesn't. They have been developped both the same day in a sequence in Xtol 1+1 in open trays in complete darkness and they come from the same film holder (one from each side, so not the same darkslides). Are these light leaks? I checked the darkslides in the dark with a fairly strong flashlight but didn't find any leaks. I could be mistaken I guess. If anyone could advice me it would be greatly appreciated. Just got myself a nice box of Provia but now I am fearfull to use it...
Thanks!
 

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cjbecker

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I second the dust issue. Its a constant battle with sheet film.
 

Hatchetman

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To be honest, I messed with 4x5 for a bit but was always having one problem or another. If I had results like yours I would have been reasonably happy. Easy to touch up in a darkroom print or Photoshop.
 

cjbecker

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Yes. Dust on film, pre exposure. It can be caused by dusty holders, a dusty changing tent, or just a dusty environment. Try cleaning your holders and wiping down your tent/bag, or load holders in your darkroom. Then place clean filled holders in ziplock bags. See if that helps.
 

MattKing

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Why would dust on the film lead to black spots on the negatives, and not clear spots on the negatives?
 

Kilgallb

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Dust on film before exposure makes black spots. (Too much experience on that one point).

Could there be pin hole leaks in the camera bellows? Maybe moisture on the film pre-exposure?
 

MattKing

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Bill Burk

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Dust on film pre-exposure keeps the film from getting exposed. They become difficult to retouch black spots on prints.

These look like light leaks but wow are they wild!
 

Mick Fagan

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To eliminate dust as much as possible, I have a compressor in my darkroom. I blow the double dark slides extensively, prior to loading film. This has been the single biggest method of lowering dust on sheet film before exposure for me.

When loading film, I never let the film touch anything once it is taken out of the box. I keep it away from anything, then slide it into the holder. By placing the film down on a surface after being in contact with your warm hands for some time as you get an individual sheet out, it will often curl slightly. Placing it on a surface may see just the central part of the sheet of film in hard contact with the surface; this is where I've seen dust pickup before. Usually more so in hot and sweaty conditions, which may be possible at the moment as you are in summer up there.

Matt, check out the positive of the man at it's biggest size, then at that enlargement onscreen, you can see hair dust and some other artifacts, which were most likely deposited before exposure. Don't ask how I know.

Mick.
 

awty

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MattKing said:
Why would dust on the film lead to black spots on the negatives, and not clear spots on the negatives?
Click to expand...
Yep thats weird.
Maybe dust after processing adhering to the wet negative.
Could try rewashing the negative and see ifvthat removes the spots.
Does look like very fine light leak from a film holder, but that would be odd.
 

rst

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A spot like light leak on the film holder is indeed weird. To me the second image of the negative looks more like there are fine holes in the plastic bag of the film and someone opened the film box and exposed the plastic bag to light. I would say it is definitely not caused by dust on the film, that would lead to blank spots on the negative and it also does not look like dust spots on the negative during drying. Such kind of dust would not cause that fogging around the spots.

Cheers
Ruediger
 

cjbecker

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My thinking was backwards, I retract the dust idea.
 

awty

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Unless the particles caused a chemical reaction causing some fogging during processing.
Very weird.
Would need to check your dark slides, then make sure your film loading and processing is clean.
 

btaylor

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What type of shutter? A deteriorated cloth shutter (like a Speed Graphic) could do this. It reminds me of the patterns I see from 35mm rangefinder cameras with bad shutter curtains.
 

laser

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Film is very sensitive to chemical materials. It might be a contaminate that rested on the film surface. It probably washed away during processing. I am aware of several instances when a lubricate used in metal "garage door" paper safes deposited on enlarging paper if the the door was opened and closed rapidly. This caused black spots.
 

Donald Qualls

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Same area, but not the same pattern. It almost looks like a static discharge, but it lacks the branching fractal pattern those often create. I have seen static marks on 120 film that lacked that "lightning" look, though. Tray development, however, isn't a ripe situation for static, because humidity work against the charge buildup. You don't use an ion gun to remove dust either while loading or unloading the film holders, do you?
 

tezzasmall

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As the OP does his own film developing, I'd suggest doing some tests with some paper negatives instead. Mostly because it's cheaper and quicker than using film to try out a few things suggested.

Terry S
 
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Photopathe

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Thanks a lot for all the replies. In answer to a few interrogations here:

-I use a Chamonix 45-F2, so no secondary shutter. Just the lens shutter.
-I do not use a ion gun or any other special device to remove dust.
-The film box was always opened in complete darkness (unless my memory is playing tricks). So the plastic bag should not be the problem. I will double check that when it's empty.
-Only these two sheets are showing this problem. None of the 10-12 sheets I developped before had that. They were all very clean.
-Some of the dust artifacts might come from scanning.

I will report back as soon as I develop some more sheets. I have a feeling the next sheets are going to be fine and that we may never have an answer to this. Don't know which is worse. We'll see.
 

Donald Qualls

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Static discharge could also happen within the black plastic bag during film holder loading. The limited area of damage looks a lot like where your thumb might land when handing the bag. Static from the plastic rubbing on the film could discharge when your thumb pulls charge off the outside of the bag.

If this is the case, you may want to install a humidifier...
 

eli griggs

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Photopathe said:
I use a 3 minutes water bath with a bit of agitation before the developer bath. Would that not have removed that dirt?
Click to expand...

Unless you used a wetting agent, and good agitation, tension might allow dirt to stay or bubbles form around these tiny bits.

I'd check my tanks, sheet film holders, etc, and rewash all my reels, etc, just to be sure they do no carry junk into my tank.

Blowing out the bellows might no be a bad idea either.

IMO.

Actual dirt on film
 
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