PDA

View Full Version : Extended developing times


John King
13th May 2016, 10:51 AM
I have always used the 'use once and throw away' principal when developing C41. If I mix say 1 litre of developer from a kit, how many 36 exp films can I expect to develop from this volume and what would you suggest to extend the times if I have to process up to 10-15 films.

I will be using a JOBO CPE2 and load the tanks with 2 films each and the quantity of developer will be 250cc

I ask this because I expect to use at least 10 films when I am over in Europe in June.

JOReynolds
13th May 2016, 12:22 PM
Film processed in partially-exhausted C41 developer is difficult to print because the shadows are stained.
I have no experience of Jobo but I developed (pardon the pun) the processing sequences for SmartLab, a rotary-discard processor, about 15 years ago and I found that the stain, measured by densitometry, was always high, especially if the liquid volume was low. SmartLab was based on the Wilkinson model, with spirals on a rotating spindle in a stationary drum. The stain could be reduced by keeping the rotation speed down, but increased markedly if the time was extended by even a small amount, suggesting that the developer was thoroughly oxidised at the 3m15 point, so I doubt that results will be satisfactory if two films are processed in 250ml, two or more times.
Neither Kodak MEA nor Fuji would comment on rotary-discard processing, mainly, I suspect, because there were so many variables. Kodak simply required that their standard was met, referring to their control strips and carefully-exposed ballast film - that we had to pay for! We eventually got there. What I also discovered was that films passing directly from dev to bleach, with separate bleach and fix worked best. The bleach and fix could be re-used several times.
My post of 30 Sept 2015 describes drying. In reading it again I sound rather pompous but the info is well-researched.

John King
13th May 2016, 01:59 PM
Thanks for your PM by the way.

I have always used C41 developer in the use once and discard principal. It was just this time I will have a good number of films to process at one time so though about saving a bit of time and money by re-using developer that has been used once before.

After reading your play on the matter, I think I will stay with the use once and discard method again. These photographs, providing the weather God is kind to me will be the only chance I get.

If I can do 2 x 35mm film in a 120 tank it will still get me 4 films per litre which is not bad. - infact a good nights work.

I anticipate having at least 10 films to process, but counting on more - at least 15 so will be taking 20 with me.

Mike O'Pray
13th May 2016, 06:04 PM
If I can do 2 x 35mm film in a 120 tank it will still get me 4 films per litre which is not bad. - infact a good nights work.



John, isn't that 8 films per litre if it's 2 x 135 per 240mls which is at least more economical. These days, apart from the satisfaction of DIY and unless you do a load of films per session I am beginning to question whether home developing of C41 is worthwhile if it is only the occasional 1 or 2 films especially when in my case I have a very well run high street mini-lab in my town.

Mike

John King
13th May 2016, 07:38 PM
yes you are correct, I never was good at adding up. 8 films indeed. I don't know, but economics never come into it really, I still enjoy the anticipation of seeing a correctly exposed and developed film coming out of the tank at the end of a session.

I stll do B&W but I find I tend to do more C41 than B&W because I find RA4 easier to print than B&W. Now that must sound odd but I have a set up where I can depend on results (usually). RA4 isn't all that difficult.