Bromide Drag equivalent in C41?

Discussion in 'Color: Film, Paper, and Chemistry' started by Struan Gray, Feb 15, 2006.

  1. Struan Gray

    Struan Gray Member

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    I send my 4x5 Portra to a lab for developing and am getting a persistent problem that looks like a light leak but doesn't make a lot of sense. I am beginning to wonder if the problem is with the lab.

    I am getting patches of odd colour and/or higher density around the corners of the film, especially on the top edge of the image. I use the Fuji Quickchange cartridges (NB: not Quickload) which other people have found leak prone, so at first I suspected them, but consider the following:

    1. E6 film in the same holders shows no patches.

    2. B+W film in the same holders shows no such patches. I also have B+W and colour neg pairs taken at the same time, in the same light, with the same lens. The colour neg has the patches, the B+W not.

    3. No patches on a sheet that was exposed to the inside of the camera but the shutter left closed. I.E. the sheet was unexposed, but was open to any light leaks.

    4. Patches on a sheet that was exposed to ambient light outside the camera for a couple of minutes. A very dense sheet, but there are still patches of odd-density at the corners.

    5. The patches are clearest on shots with high density near the corners: i.e. skies or snow. Dark areas do not seem to be affected as much.

    6. The odd patches are always 3-4 mm in size and form a lozenge shape around the clip holes from processing.


    I am reluctant to blame my processor for a fault that may be mine, but it is beginning to look to me as if development byproducts are being retained by the clips used to hold the sheet while processing. These are thenaccellerating development.

    Is this a reasonable thing to suspect, and can it happen in a dip-and-dunk C41 processing line? In B+W I would suspect insufficient or too-unidirectional agitation, but I am very much a paint-by-numbers person when it comes to colour processing so before I start complaining to the lab I would appreciate comments from people here.
     
  2. LAMitchell

    LAMitchell Member

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    Definately sounds like cross contamination to me. I get something similar with the Nova sometimes when doing RA4 processing. Its usually caused by a very small ammount of BLIX left on the clip if I havent washed and dried the clip properly. When I clip on some undeveloped paper some contaminates the paper around the clip before it is washed off in the dev. Personally I would be tempted to buy a Jobo and dev the film myself.
     
  3. Struan Gray

    Struan Gray Member

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    Thanks LA. Glad I'm not just clutching at straws.

    I do have a Jobo CPE and am idly following auctions for 4x5 reels on eBay, but it's hard for me to have a darkroom in our home at present.

    The lab is Peak Imaging. They have always done such good work for me with other formats, and with B+W and E6 in 4x5, that I am reluctant to send too hefty a brickbat their way, especially since I'm not 100% sure that the fault is theirs.
     
  4. Kino

    Kino Member

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    Well, if the lab manager has an bit of good sense, they will thank you for bringing it to their attention, PROVIDED you do it with a good attitude and a genuine desire to find and correct the problem regardless of WHOEVER'S (whomever's?) fault it might be.

    Save the brickbat for the eventuality that they do not respond or dismiss your problems out of hand.

    My 2 cents...
     
  5. Struan Gray

    Struan Gray Member

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    Never fear. I'm instinctively a more-in-sorrow-than-in-anger sort of person anyway.
     
  6. Photo Engineer

    Photo Engineer Subscriber

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    Struan;

    C41 films contain high iodide emulsions with DIR couplers. This combination could end up with a film sensitive to a 'bromide drag' effect where the effect is due to iodide and the DIR 'fragment' which inhibits image development and causes edge and interimage effects.

    This would take place with improper agitation, bad replenishment, or mixed Kodak - Fuji products in one process (or mixed products of one mfgr of different types which are highly unbalanced in type).

    It is not unusual to see this. We were very careful at EK to make sure that the cross product 'contaminaton effect' was minimal, as we tried to balance halide and DIR effects across films, but with todays UC and VC films this is probably much more difficult to achieve.

    I would say that you should bring this to the attention of your lab and show them some of your negatives. BTW, E6 is also prone to this type of effect under the right 'wrong' conditions.

    PE
     
  7. Struan Gray

    Struan Gray Member

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    Thank you PE. I'm afraid I don't know what "DIR" stands for: is it the remains of the sensitiser dye, or one of the bits that are left over once the colour dyes have been formed?

    I have read that saturated films can use a trick where development of one colour releases reaction products that suppress development of the other layers. I would be interested to know how much such inter-layer effects are universal in colour films, and how prevelent they are in my preferred low-contrast films. If you're allowed to tell us of course :smile:

    These patches definitely require the area near the clip marks to have been exposed. I have a pair of negatives of the same scene, one taken with a badly adjusted compendium shade, and one with the shade correctly positioned. The vignetting by the shade has supressed the patches, despite the fact that it is not extensive enough to cover the entire patches had there been any.

    I will try and find time to scan one or two negatives so this can sit in the archives. I am also interested in hearing more experiences from anyone who has seen anything similar.
     
  8. Photo Engineer

    Photo Engineer Subscriber

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    Struan;

    DIR = Development Inhibitor Release.

    During development, a very strong inhibitor is released during color dye formation. This DIR fragment inhibits development causing either edge effects or interimage effects. One improves sharpness and the other can improve either grain or color quality.

    Either way, if it is incorrect, it can look like bromide drag of a sort, causing streaks or blemishes in the image as you describe. Very often, the fragment released is similar to pheny mercapto tetrazole (PMT), a common antifoggant.

    PE
     
  9. LAMitchell

    LAMitchell Member

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    Does the DIR get effected by a pre-wash?
     
  10. Photo Engineer

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    DIR couplers are not affected by a prewash in any way.

    PE
     
  11. Struan Gray

    Struan Gray Member

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    Thanks again PE. I appreciate your abilty to simplify just enough, but no more.

    In case anyone else has a similar problem, or like me has gone mad in an orgy of self-doubt when chasing a light leak, I have appended two images showing the effect to this post. The first shows the effect on the pictorial content of the image, the second has has the colours and tonal scale fairly radically munged so you can see the film edge, the clip marks and the extent of the damage all at once.

    Of course, this may still be a light leak. I'll report back on the lab response, if any.
     
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  12. Photo Engineer

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    Struan;

    After seeing the actual pictures, I can say that this does not look like a classic case of 'drag' or bad agitation. It also does not look like contamination, as the usual contamination would darken the image or change its color rather than lighten it in the positive image.

    You see, bleach contamination or fix contamination lowers the amount of silver developed and therefore the positive image is darker.

    Also, the lightening didn't 'bloom' into the dark edge as it would with chemical contamination.

    This looks more like a light leak of some sort than anything else I have ever seen.

    I'm always glad to try to help or try to clarify.

    PE
     
  13. LAMitchell

    LAMitchell Member

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    Definately looks like a light leak, just seems a strange spot for it to apear! Would you expect to see something on the film rebate too?

    I am a bit suprised the Lab hasn't picked this up either, what kind of QA do they use?
     
  14. Struan Gray

    Struan Gray Member

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    Thanks PE and LA - I think :smile:

    I'll do a few more tests in a couple of weeks when I'll have time off in the daytime for fooling around with cameras. I'm pretty sure I have eliminated most of the obvious things, but I want to pin this down before I head to Scotland at Easter.

    The odd thing to me is how the appearance or not of these patches is mostly unrelated to how I have handled the film holder and cartridges. Also that B+W and E6 are unaffected. One option is that the leak is always there, but is only significant when expanding the low on-neg density range of my twilight Portra shots. On more contrasty media the leak may be too subtle to show up.

    Ah well, I appreciate both of you chipping in, and will report back if I get a result. Even if it means tucking in to humble pie.
     
  15. LAMitchell

    LAMitchell Member

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    If you can a control would be to get some film processed at another lab and see if they are the same.

    Scotland is nice, we will be going up there in July for our anual trip to Arran. If you are near London give us a shout. It would be good to meet up with another analogue user :smile:
     
  16. Struan Gray

    Struan Gray Member

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    Small world. Easter will be my first time on Arran - I'm looking forward to finally seeing the place. We are combining it with our usual run to Coigach and visit to granny in the Borders.

    It would be good to meet. I keep promising myself some time in the print room at the V+A, and I have an unused voucher for tea at the Ritz I need to use up. Somehow though I don't see my wife agreeing to substitute tea companions from the APUG chaperone pool :smile:

    Have you seen the UK APUG get-together threads? The visit to Ilford's factory should be a great opportunity. User 'mark' also frequently coordinates informal meets in London itself.

    Of course, you and any APUGers passing through southern Sweden or Copenhagen are welcome to come and visit. There are also rumours of another Nordic LF meet in Stockholm this summer. So many workshops, so little time .....
     
  17. Photo Engineer

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    Struan;

    It would be unusual for hangers to be exchanged between c41 and E6. Therefore it does not surprise me that there might be a difference in 'cleaning' of the hangers of the different processes.

    IDk, but FWIW, looks like a light leak problem.

    PE
     
  18. Struan Gray

    Struan Gray Member

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    An update for the sake of closure.

    I think I have solved the problem. No doubt it will reappear with an Olympian distain for Hubris once I hit the 'Submit Reply' button, but after a spring and summer of testing I am now confidently using my Quickchange system again.

    In short, engaging the Graflok slides after inserting the Quickchange holder has completely eliminated the odd patches, even on colour negative film shot in very flat, low light. The Quickchange holder is quite thick, and more importantly, long. I suspect that in operating the mechanism I was inadvertantly levering the holder away from the back by a tiny amount.

    Thanks again to those who took an interest in my problem.
     
  19. coigach

    coigach Member

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    Hello,

    This is nothing to do with the price of fish (!) and is a year late in any case, but it's nice to see by chance an image taken at my favourite bit of the world.

    Struan, I've taken many pictures by this particular lochan, and would recognise Achnahaird bay and the distant profile of Quinaig anywhere! :D Am heading up there on a photo trip in a couple of weeks time...

    Cheers,
    Gavin
     
  20. Struan Gray

    Struan Gray Member

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    Cheers Gavin. Coigach does tend to get under people's skins. Your handle is a bit of a give-away :smile:

    I used to dash up a hill once the children were asleep and sit on top sky-watching until midnight before yomping down again. Some tops, like this one, I got to the point where I could almost set up the camera using the tripod head's panoramic angle scale and a compass bearing.

    That said, the kids' term times now see us going in July rather than June, and the atmospherics are less delicate and subtle, so I've been spending more time following streams and coastal clifftops. This year's almost total lack of midges meant I covered a lot of sodden ground I usually avoid, although I still haven't dared tackle the boggy patches of huddled woodland on the south side of Loch Osgaig.

    From having been the sort of person who always carries three spare spoons and a backup granite sundial I now personify the middle-aged prat everyone scoffs at in the mountain rescue reports: falling into bogs in jeans and wellies at one o'clock in the morning, with no one to hear my cries, much less lift the rucksack off my head.

    Have fun. When we lived in the UK, late autumn and Easter were our favourite periods to visit.


    Struan

    PS: the light leak hasn't reappeared, so my solution does seem to be the solution.
     
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