development flaws on 8x10 portra

[carleton]

I photograph landscapes in overcast, flat light, using Portra 160. My exposures are dead on. I keep getting problems with flawed development; this shows as faint brown smears in pale areas (eg. grey skies). My film is in perfect condition. I avoid damp, heat etc and am meticulous. I have tried processing in various labs but keep experiencing this problem. I scan my film and produce Lightjet prints; these flaws ruin so many negs. I have been told that one problem is that modern dev tanks are smaller than the very large old ones, and consequently the chemistry does not engage consistently with the 8x10 sheet; it has been suggested that I have a technician develop the film at a lower temp for longer. Does anyone have any experience or thoughts on this problem? I'd be grateful for help.
Thanks
Michael
P.S. example (in exaggerated form to make flaws more visible) attached

[Mark Crabtree]

Do you know what type of processor the various labs used? Continuous processors, dip and dunk, and rotatry processors are so very different from each other that it would be very odd for the same issue to show up with different methods.

At a guess, I would have thought this was a bleach or fix issue, but that coming from more than one source seems odd. I did extremely large negatives by all kind of crazy methods and never recall having that particularly problem. Inadequate agitation would be a possible contributing factor, but not likely from a variety of labs.

Hopefully someone from one of the current labs posting here will have a better idea of what is mostly being done for 8x10 C41 processing today. I'd be tempted to get someone to run some in a Jobo Expert drum.

[Andrew O'Neill]

Where's the example?

[interneg]

Inconsistencies with dip/dunk machines & 8x10 are not unknown - if two were above each other, the lower could be denser than the upper owing to the time taken to submerge & the short developing time. Have you had optical prints made &/ or the negs scanned on different scanners to eliminate the possibility that it came from somewhere else in the imaging chain? Are the flaws observable under direct magnification on the negative?

[Eric Leppanen]

This sounds like the mottling I experienced on my 8x10 negs with some dip-and-dunk labs: faint light blobs, streaks and blotches particularly visible in relatively clear areas of the negative such as open skies. My understanding is that this results from inadequate agitation. My local B&W lab at the time resolved the problem by upgrading the agitation in their Refrema machine. For C-41 I had to switch to another lab. I experienced this problem only with 8x10; all the labs had no problem with 4x5.

My suggestion would be to try finding a lab still running a Refrema (or something similar). Of course very worst case you could ship your negs internationally, I had many of my 8x10 C-41 negs processed at Edgar Praus in Rochester, New York without problem. He runs Refremas and was familiar with the potential problems with processing 8x10.

This mottling I experienced was clearly visible on a light table and was not a scanning artifact.

[Mark Crabtree]

https://www.largeformatphotography.info/forum/showthread.php?136608-Processing-flaws-on-Portra-160-(8x10)

[Wayne]

Where's the example?

Yeah, there's no attachment.

[cdavis324]

Praus has the direct solution. It's the only place I'll have 8x10 developed. You could also use that nyc lab that created the slow processing... If you want to pay double and are fine with their round about solution.

Sent from my LM-V350 using Tapatalk

[interneg]

It would help if the OP told us which labs they have used - the chances of them having really tried all the available labs over here that handle 8x10 is small.

[carleton]

187914
Hi,
Thanks. Apologies for my tardy response - been away. Hopefully my jpeg of a flawed sky is attached for you to see. The flaws are particularly evident on pale neutral areas - and a lot of my exposures are of such subjects.
Thanks for any advice. The response above from Eric Lappanen sounds as though this might be the answer, but I live and work around London and hate the idea (let alone expense) of shipping negs abroad and back.

[carleton]

Eric
Thank you very much for your insightful response to my query. Attached is a sky showing the effect (darkened to make it more visible).187915

[carleton]

Attached is an example:187916187916
Thanks for responding. This flaw is killing my work. Any subject that is primarily light neutrals (which is the character of a series of views overlooking an estuary in overcast light that I want to do) is doomed. It would be enough to make one shoot digital (I'd rather shoot myself).

[carleton]

Hi
Thanks for your helpful response. Please would you tell me which NYC lab does slower processing? If they'd tell me their process, I could ask a lab here (London) to try the same method.
Thanks,
Michael

[interneg]

Hi
Thanks for your helpful response. Please would you tell me which NYC lab does slower processing? If they'd tell me their process, I could ask a lab here (London) to try the same method.
Thanks,
Michael

Have you tried BDI - http://bdimages.co.uk/? They are one of the few remaining specialists in C-41/ RA4 custom optical printing (though they do scanning/ retouching/ C-print too) & are world class - I think they'd be the sort of place willing to try a few work-arounds to sort your problem - for example it was Brian Dowling who largely worked out the classic cross-processed look for Nick Knight & how to print it creatively.

[Chester McCheeserton]

LTI in new york does the slower processing. But you won't want to pay for very many sheets.. it's $$$, I think they just only use the top or bottom rack or something, try talking to them...

Darkening the sky is always going to show imperfections, it's like looking at a darkroom print to decide what to spot with those jewelers googles, at a certain point it's not helpful...you'll never be satisfied...

How was your scan made in the example you provided? for pictures like your example, you're gonna need a wet mounted drum scan and then some serious hours retouching out the imperfections...there will always be some there....whether it's surge marks from the clips or just overexposure or overdevelopment at the edges, the wet mounting helps with capturing the smoothness some.

I worked at lab many years ago who was drum scanning a very well known color landscape photographer's 8x10 negatives with lots of sky - he started returning the scans after darkening them with an adjustment layer, they did look bad when darkened but try it with any neg scan with sky – it will always look bad.

I suggest renting a medium format digital camera like the fuji rangfinder, and shooting the same scene with film + digital...I know that's not what you want to hear but...at a certain point hours spent scanning and fighting the process become...not worth it if the result isn't better.