Jobo 3010 Question

[Jeff Moore]

O.K., my normal development procedure is to develop 10 sheets (4x5) at a time in a Jobo 3010 drum on a CPP2, using 500ml of developer. Of course, I always have different numbers of sheets to develop at N, N-1, N-2, etc., which all require different development times. If my normal process is to run 10 sheets at a time with 500ml of chemistry, will the development be off if I have, say, only three sheets in the 3010 and use the same level of chemistry (500ml)?

[paul stimac]

Go to http://www.jobo-usa.com/
click on the <Analog Service> link
click on <Expert Drums> link
scroll down
for your example of 3 sheets in a 3010 they recommend 210ml's

[Ron Marshall]

A good friend who attended a workshop with John Sexton told me that John always puts unexposed sheets in his Jobo to compensate when developing less than the number of sheets that he standardized his process with.

I use less developer when I have fewer sheets and have never noticed a difference. However, I have never tested to see if there is a difference.

[Jay DeFehr]

I think a lot depends on the developer one uses, and how near its capacity. I use 510-Pyro 1:100/500ml for 10 sheets. 510-Pyro requires less than 1ml of concentrate to develop an 8x10 sheet of film, so 500ml of 1:100 dilution is enough to develop 20 4x5 sheets of film, or double the capacity of the drum, which I consider a good safety margin. I've seen no difference in my results wether I develop 1 sheet or 10. If I was using 500ml of Xtol 1:3, I'd expect the number of films in the drum to have a much bigger impact on development.

Jay

[Eirik Berger]

As Paul says you need at least 210 ml of chemistry for the 3010 expert drum. If you use less the sheets will not be entirely covered. I use mostly Jobo E6 chemistry with my 3010 drum, and jobo says you need at least 33 ml of their (fresh) chemistry for each 4x5" sheet.
So then it is only to calculate, when I develop 6 sheets or less I always use 210 ml (6x33ml=198ml which is below minimum quantity for the drum). For a full drum of 10 sheets I use 330 ml of chemistry.

For BW chemistry I do pretty much the same thing. After reading the specifications of the chemistry I find out how much chemistry needed per sheet. Then it easy to calculate how much is needed in the drum. I most often use use-once-then-throw-away developers such as Xtol (1+2 or 1+3) or Artdol.

[Bruce Watson]

If my normal process is to run 10 sheets at a time with 500ml of chemistry, will the development be off if I have, say, only three sheets in the 3010 and use the same level of chemistry (500ml)?

Development may be off a bit, but if it is it is probably a very small error. The reason for it would be that fewer sheets would change the rate at which the active ingredients are used. Near the end of development you would have more active ingredients available with three sheets than you would with 10 sheets. The question is, would you notice the difference in the final prints? Of this I am doubtful, but the only way to know is to try it.

One way to compensate would be to use less developer. For example, if you use XTOL at 1:3, you need a full liter for ten sheets. You'll be on the edge of what Kodak recommends in terms of stock XTOL per sheet. If you drop to three sheets, drop to 300ml of XTOL 1:3 which should result in the same rate of use of the active ingredients. That is, you'd match the rate of use that 10 sheets experience.

Another way is Sexton's method - for every two empty slots, put in a single sheet of fully exposed film.

A third way would be to just wait until you accumulate ten sheets to process. B&W film is very good about this. While it's "best" to process soon after exposure, you can usually store exposed film for many months before processing with no noticable ill effects.

But really, what you propose will probably work just fine and give you results that closely match what you get when you run ten sheets at a time.

[Jeff Moore]

Thanks for all the responses. You've answered my question.