partially fogged film ?

[ken currie]

i'm hopeing someone here can tell me what my problem is ...... SOME of my negs are coming out fogged a consistent 3 1/4 inches .... i.e. there is a 5 in by 3/4 strip of normally developed film while the rest is VERY noticably fogged. This has happened in tray processing and tube processing to some, but not all negs in a batch??

I am fairly new to LF but have developed 1000's of MF films in the past and believe that I'm consistent with all steps along the way.

Rather than me continueing to scatch my head over this issue , i'm wondering if i'm missing something obvious, such as bad holders or ????? I DON'T KNOW .... help !!

ken

[Darryl Baird]

it's possible you have bad light traps (aka a bad holder)
--run a test with paper loaded and see if you can reproduce the fog without making any exposures... just put the holder into the camera, leave for a few seconds, remove and replace the dark slide, and process

Questions:
Is the fog nearest to the top (where the slide enters the holder)?
Are the holders easy to get into and out of the camera back?
Are all holders the same type... wood, plastic, etc.?

[ken currie]

the holders are all plastic ....fidelity and lisco.....and look to be in very good condition ... all load into the camera about the same ..... the fogging pattern is exactly the same on all bad negs .. looking at the emulsion side in a vertical postion the fog runs right to left...... meaning the fog is coming from the side of the holder not the top ..... which leads me to ask if it is possible that i'm not seating the holder into the back properly .......would that lead to this problem? ken

[Darryl Baird]

RE: "which leads me to ask if it is possible that i'm not seating the holder into the back properly .......would that lead to this problem?"

sure, but the variables of pressure and force used to manually load film in and out tends to make me think that you should at least also consider a bellows leak or a bellows/camera back that isn't fully sealed/connected... due the the consistency of the fog

1) watch how each holder enters the back and see if there is something possibly causing a slight rise to only one side
2) look at the place where the bellows attaches to your back (btw, what camera?)
3) look at the camera's back light traps... are they in good condition, the felt intact, all grooves/slots match up, etc.

[ken currie]

the camera is a shen-ho in mint condition .... i re checked the bellows last nite and everything seems in order ....i cannot see any lite leaks with or without a holder in place ..... i developed 8 negs last nite .... 6 were fogged ...... the day before i developed four exposure test negs .... they were absoluty perfect ??? I normally can trouble shoot things like this myself ... but this one has got me confused to the max .... btw ... i apprieciate your input ... ken

[kev curry]

Ken, sorry I have to ask......... are you Ken Currie of "New Glasgow Boys" fame?

kev

[ken currie]

no .... far from it ...i'm in canada... altho i'm am a fairly well know musician on this side of the pond

[Clay Turtle]

Ruling out the camera & holders & that different film inicating the film wasn't fogged, I would ask are you (the camera) in direct light during these incidents? Are you leaving the dark cloth over the back when you have the slide out making the exposure then returning the slide? I have had problems like this when shooting in direct light (gets pretty warm down here so I generally try to set up in the shade)?
PS As the fog seems to extend across the film plane (assuming horizontal or landscape format) indicates bad seating or light leak in back plate so you might try gluing some black felt to it. That being to the camera side of the frame, not the gg side. Thus you are changing the distance of the gg & the film plane but they remain constant (consistent distance as both are moved slightly)

[ken currie]

these have been shot in full sun ...and no i don't cover the back with a darkcloth when the slide is out ...... i didn't realize that would be and issue ??

[Clay Turtle]

Ah, yes I use a rather large loth I had made up, generally I cover the full length of the camera (from the front standard to the rear standard) as well as keeping it shut (closed) during exposures.

[Clay Turtle]

Ah, yes I use a rather large cloth I had made up, generally I cover the full length of the camera (from the front standard to the rear standard) as well as keeping it shut (closed) during exposures. Sorry about the spelling error (typing) but your response came as I was shutting down.
To an extent there is necessity of leaving the back covered: I would point out that as I intend to build an 8x10, necessary info is the size of the film holder [ => standard, etc] for such a build I bought some online. One thing I did note about these holders is that the greater distance (length of the sides tends to allow more flex) such that when the slide was removed the side wall bowed opening a gap which would allow light to fog the film in the holder. Of course these are used plastic holders of larger format than the 4x5. It convinced me that precautionary leaving the dark cloth in place would best serve as a procedure.
It paid off in short order. I was using the 5x7 which is a build in progress but not have any gg. for it I used an Bender kit camera [that was part of the base unit on which the build was being made] as the film holder / gg section fit nicely into the hole (cross sectional area) in the 5x7 back, the only problem was it didn't extend to the edge which meant , it was secured in place. I had taken one shot [back ground are (upper portion) & turned the camera about 90 degrees to do the second when the sprinkler system came on. A moment of blind panic . . . fight or flight syndrome was over come as I watched & noted that the nearest rainbirds clicking away weren't patterned to water the area where I was set up. As I was already holding the release cable in hand I decided to chance it & took the shot. Now I was still vaguely feeling that flight emotion & was about to remove the dark cloth rather than going under it (after all it was still dark out) to re-insert the slide. But good procedure won over & I only lifted the dark cloth finding that 4x5 bender part was in fact caught in the folds of the cloth as it had fallen away from the back plate. If I had simply removed the dark cloth, holder & all would have fallen exposing (fogging) the slide film.

[Clay Turtle]

One thing I did note about these holders is that the greater distance (length of the sides tends to allow more flex) such that when the slide was removed the side wall bowed opening a gap which would allow light to fog the film in the holder. Of course these are used plastic holders of larger format than the 4x5. It convinced me that precautionary leaving the dark cloth in place would best serve as a procedure. Added tidbit of info. Later you may ask yourself why or what is the difference between plastic & wooden holders? Important aspects swelling vs expansion & contraction vs heat absorbtion & thermal decomposition.

[gbogatko]

I've had a nasty fogging problem with an 8x10 holder -- the whole sheet fogs up on both sides of holder B, no problem with holder A. Holder A used under the sky, holder B in shade. Examination of holder B (the fogging one) shows signs of some kind of repair along both edge seams. I've bit the bullet and ordered 2 new ones.

george