Unfortunately I can no longer find the page with the examples of "mottling". Not a problem inherent in the film but rather an issue with c-41 and large format film. As a landscape photographer I know exactly what you're talking about. Have your lab turn up the agitation on their bleach bath and see if they'll run your negs on the very bottom of the rack.
Originally Posted by frotog
I think I have an example of this from a colour ad in VC mag somewhere. I will try and find it and scan just for illustration.
Thanks for the feedback...I was starting to think that I had a problem on my side especially when so many Labs in London have shown the same problem. Thanks as well for the heads up on the Lab in NY...I will give them a call this afternoon...I will also see my Fuji test today so I will post this evening with results.
Well it seems that the Fuji film (I have not seen it as yet but have been told by the lab) also has the marks...so it's not film related, nor specific lab related so looks more more like it's a processing problem. From my research it also seems that it's not country specific as I have found a lot of reference to it happening in the US as well...see the links below..my feeling is that emulsions have had changes eg 160nc to 160nc II but the chemistry hasn't so the emulsions and chemistry are no longer in tandem with each other. I did some bespoke scans last week on my Tango drum scanner from a photographer who had shot 160nc ( not the new or newish NC II ) and his skies were clean and even. There are a few labs in NY who suggest that they have solved the problem by adjusting their machines..I would be curious to hear if any of you have had clean/clear results..as I said earlier this problem is at it's worst over areas of flat mid or darker tone. Frotog..I see that you have been posting to other sites with exactly the same question..One theory that I had when discussing this with my lab is that the development seems to be quite aggressive, with the developer possibly being too strong for newer emulsions..so..when the hangers rise from the developer and move towards the wash the developer is still working on the film ..but being a liquid it is being pulled to the edges ..this would have the effect of pushing slightly the outer areas of the film ..maybe only a 1/4 of a stop...the mottling on my film tends to be in the center of the neg..my lab is going to run a sheet with the light on to watch how the liquid travels over the sheet when it exits the dev and then time how long the top sheet ( which is out the longest ) is out of the dev to see if it's possible that it is being pushed...it's just a theory..I will keep you posted
http://www.largeformatphotography.in...ad.php?t=14348
http://www.largeformatphotography.in...ad.php?t=65445
http://www.apug.org/forums/forum40/1...-problems.html
http://www.apug.org/forums/forum140/...abs-nyc-3.html
...just to add...I forgot to say that the scans that I had done of the other photographers 160NC had been shot and processed over 8 years ago....has anyone any recollection of when they first noticed this problem starting??...
Mottling in C41 processing is not unusual and seems to be somewhat lab-dependent, thought I imagine it could change over time at a given lab. It's made me consider switching to E6 on occasion, but I really like the look of negative film.
I started shooting 8x10 in around 2004 and had great results from a lab in NJ (Taylor Photo). When I moved to New York, I started using Duggal and had mottling problems. I tried a few other 'pro' labs with the same problem. I did not know of LTI at the time. Eventually I found a place called PixPoint, and their processing was perfect with no mottling. PixPoint is an amazing lab, they specialize in only C-41 film processing and wet c-prints.
Now I'm shooting 4x5 and I've had no mottling with Samy's or Taylor Photo in NJ (But I use Samys since it is cheaper and mostly because Taylor can't seem to get the clip marks anywhere close to the edge of the film!!!).
LTI claims that their special C-41 line run slower and cooler, which makes sense since presumably increased time in the soup could make the development more even.
I shoot a lot of photos with flat, overcast skies, so the mottling is very obvious and a big problem when it occurs.
The processing at PixPoint was, by far, the best, cleanest processing I've ever had. But it's not cheap, nor is LTI's modified process, which costs more than their standard C41 line.
Yeah...LTI charges 2x their normal c-41 for special processing. It kind of bugs me that you have to go through Lightwhatever to get the kind of attention they used to give to all their orders.
Back when Joel was running Exhibition prints one of the girls told me that the special process was merely a standard refrema process with one rack run at a time, rack halfway up from bottom to top.
Edgar Praus, whose c41 is far superior to anything in nyc these days claims to be cognizant of this problem. He says he fixed it with increased agit. in the bleach.
I haven't noticed anything in my negs from Edgar yet so maybe he's onto something. Definitely seems to be most noticeable in bald blue skies so not so much a problem for those dry kraftwerk landscapists who prefer nothing but overcast.
I am now pretty much convinced that the mottle effect that I am seeing on my sheet film is due to uneven development taking place when the hanger moves from the dev to the bleach. Have you ever seen the halo or glow that sometimes sits around where the clip marks are? I think this happens because gravity pulls the dev down and around the clips where it sits while it is being carried over.Now if you consider that the dev Tim is 3 mins and 15 seconds for a normal development then it only requires 30 more seconds to push the film a half stop. I think that the same thing happens to the rest of the sheet. As the sheet is carried over the dev naturally gathers and runs in 'rivers' off the sheet to the bottom.I think that where there is more dev in the channels or rivers iris having more development. This would be most apparent on the first sheet on the hanger to leave the dev as it is also the last to enter the bleach and the carry over can take quite a few seconds. I tested 5 different labs with the same exposures and they all had the same problem so it must be something pretty uniform in C41 processing that would account for it..that's why I don't think that it happens in the bleach, dev or agitation because they can't all be running a bad process. Consider this..if you do not have an even coverage of developer over the neg when dish developing then uneven development will occur....so.. I was told by a Fuji expert that the carry over time was part of the overall dev time..In that case I think that because the dev will not drain off the neg evenly some pushing takes place in the areas that have more liquid..this pushing may only be about 1 third of a stop but this would be enough to cause the mottle that we have been seeing.
The mottling of large areas of continuous tone is a known problem to photographers who shoot a lot of sky and other subjects where tone doesn't change much. Negs with a lot of detail don't suffer this problem and larger films (8x10) are more effected than smaller ones (4x5).
The only way I've found of avoiding the problem is to process myself in a Jobo drum using Tetenal chemicals.
This is all very interesting - as I've had exactly the same problem. A sort of irregular brown staining.
For me the issue started last December and it was a snow scene. Initially the thought was moisture or condensation - but I am very rigorous regarding this issue. However it has happened repeatedly this winter - my thought was a problem with temperature and humidity as I have been shooting a lot in the snow and close to the cloud base.
I contacted Kodak UK who said it was moisture. As I say I have a rigorous procedure re allowing the film temp to change gradually, using zip lock bags / desicant sachets etc.
The issue has occurred when films were processed by 3 different labs.
The key point to me is that this has only started when the emulsion was changed. As I'm sure you are all aware the emulsion batch number is printed on to the edge of the film as well as being on each box - and I always note the number down on storage sleeves for archival reference.
Portra 160 NC emulsion 3261 was fine
Portra 160 NC emulsion 4021 was fine
The issue started when using Portra 160 NC emulsion 4031
I may not be Sherlock Holmes but....
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