4x5 color negative processing problems

[James Via]

I have have had no luck finding a pro lab that can produce uniform processing. My 4x5 Portra VC shows irregular densities or mottling is clear a blue sky. This was all using dip and dunk. The one JoBo lab produced streaking. Film and equipment have been eliminated as possible cause - I have used different emulsions and have run Portra NC, Portra VC and Fuji NPS. B&W negatives from of the same shot look fine. Trans parencies look great too. This is a color negative processing problem. Anyone else experiencing this kind of thing?

[ronald moravec]

Mine goes thru 10 sheet expert drum using Tetenal Press Pack powder chemicals. Never a problem.

Dip and dunk sounds chancy with hangars unless they use gas burst agitation. Agitation is required every 15 sec. You can`t dip and dunk that fast. Mottling will result.

The six sheet Jobo reel will streak unless it is the newer one with the " wings" to hold the sheets on the reel or if they do not use them. Ask to see the equipment. Don`t tell why and if there are no holders on the outside, black plastic, ask about them.

If my Jobo quits, I will process color neg in a 4x5 Nikor tank. Inversion 1 per 15 sec.

I use Portra VC. The Tetinal chemicals are a near clone to c-41 . Others are not such as unicolor.

[paulr]

How much more difficult is doing your own c-41 than doing black and white?
I never considered doing it before, but now that I see what the lab charges, that could change.
I'm used to using a jobo tank on a roller base, and can typically keep my chemistry within a degree or half a degree.

[Mark_3899]

Easy. I've been doing it myself since 1985 when I worked on a hand line when I got out of art school. I process my 4x5 sheets in 3 Kodak hard rubber tanks which are placed in a Phototherm recirculating water bath. No problems.

[ronald moravec]

How do you agitate with the hangars and tanks? Kodak calls for once each 15 sec. I would raise, tilt one way, imerse, and repeat four times per minute alturnating direction of tilt.

[Mark_3899]

When I first immerse the film I agitate for 15 seconds, Then every 30 seconds I do what you describe above, which lasts about 15 seconds so in effect it's like agitating every 15 seconds. Since development only lasts 3 mins, 15 seconds it isn't too bad.

[Ed Richards]

I have good luck with Primary Color Lab in New Orleans, and they only charge $1.77 a sheet. It is generally out the door the day after they get the film.

http://www.primarycolorlab.com/

[James Via]

Interesting, I wasn't aware of people acutally hand processing C41 the very short development times spook me a bit. Trying to be consistant and all. So I've been doing more reserach on C 41. Any feed back on the different chemisty brands. One article I read stated that Kodak's Flexcolor chemistry produces a little less contrast than the others - that may mostly be true in automated machine processing. Has anyone tried C41 processing at temperatures lower than 100 - say 85 to lenghten the development time? I wonder too about push/pull processing for contrast adjustments.

Thanks

[Mark_3899]

I use Kodak Flexicolor C-41. For me the fact that it comes in containers to make 1 gallon, instead of 5 litres is a plus, it's also cheaper. I don't know about the lower contrast issue with the Flexicolor chemistry, that would only benefit my work anyway. As far as lattitude goes you really don't have that with C-41. It's not like E-6 where you can push and pull to the benefit of the shot. 3:15 is perfect for me because I'm focused on agitating the whole time. if it were longer I might zone out or get into the music I have playing.

[M Brian Mills]

I have done a fair amount of hand-processing C-41 film and have found that the single-most important part of it is a pre-soak. Without it I get all sorts of strange results and they have not been the happy-accident sort of strange results.
I have found that underdeveloping (at about 3 minutes) works well for me by giving the density that I desire which works hand-in-hand with my over-exposing.
I worried a bit about consistency, but then decided that there is a good chance that the labs I used were not so consistent themselves.
Chemistry at + or - 3 degrees and I still get results that I can easily work with.