EOuld appreciate help on this issue: Jobo suggests that using dilute developer in its drums requires more than the mfg. recommendations. Ex: According to Jobo, Kodak states that 100ml D-76 will process a 35mm 36 exp. film. Jobo suggests that one must use 130ml per roll if one dilutes the developer (I assume the dilution is 1:1). So my question to those who have experience with jobos, is this: if you use the drums to develop 35mm film and/or 4x5 8x10 film--those are the films i will be using, what dilution with a standard developer like d-76 do you use? If you aim toward a certain quanity of mixed, diluted developer at 1:1, do you use say 200ML developer + same quantiry of water, or do you use Jobo's suggestions? or do you always include more chemistry plus water than minimally needed? Sorry for the question's length. i've read the jobo intsructions and surfed its website and cannot find the answer there.

-- Bob moulton (bobmargaretm@home.com), January 11, 2002

Answers

Bob,

I have always stuck to the conventional 100ml of stock before dilution with JOBO processing. I have never had any problems with consistency for D76, Xtol or HC110, the three primary developers I use with the JOBO. This is for 80 sq in of film. You can get away with 80ml with D76 but have never tried with Xtol. If you are just diluting 1-1 you can play it safe and go with 130ml. Any higher dilutions I go to a larger tank or tray process LF negs, although you can reduce the number of negs (say 2) and reduce stock to 60 or 70 and get a higher dilution ratio.

Good Luck,

-- James Chinn (jchinn2@dellepro.com), January 11, 2002.

One more caveat, It is good practice to keep with one set quantitiy of stock for dilutions once you decide. With the JOBO system I have found that small changes in chemistry can make major changes in neg density. Consistency in methods will provide consistent negatives.

-- James Chinn (jchinn2@dellepro.com), January 11, 2002.

Bob,

you have to take care, that you do not fall short of the minimum quantity of effective developer required. This depends on the developer used and is usually stated for 80 square inches of film in the data sheets. Kodak recommends to use at least 237ml of 1:1 diluted D-76, which already requires an increased development time. See Kodak document J-78.

BTW: in my opinon, D-76 is not well suited for rotary tube development. You will get less sharpness. Rotary tube development does not support edge effects.

Regards,

-- Thilo Schmid (tschmid@2pix.de), January 11, 2002.

I found that 60ml D-76H stock/roll (used 1:3) yields identical EIs and curve shapes to 120ml stock/roll (used 1:1), therefore with the films I use 60ml stock/roll is sufficient.

However, note that this may be close to the edge of sufficient capacity and may be too little stock if the developer's a bit too old etc.

So I usually use D-76H 1:1 in the Jobo; this dilution can always allow more than sufficient stock.

The solution amounts listed for the drums are minimums and you can always use more; for example, although the 2523 needs 270ml minimum solution to cover a 35mm film the drum can be used with up to 600ml.

-- John Hicks (jhicks31@bellsouth.net), January 11, 2002.

Jobo sheet film tank 2509N needs about twice the minimum volume recommended just to start. Why? Otherwise you're prone to get weird, unremovable spots across your sheet film which occur in the first fractions of a second when the first solution (either pre-soak or developer) splashes tiny drops of fluid across the dry emulsion. This occured even though I was using the Jobo Lift.

I found these annoying spots disapeared when I doubled the minimum volume, as recommended by a technician at Jobo, if I recall correctly.

I don't know yet if this is an issue with the 35mm tanks or with the expert drums.

-- Andre Noble (andrenoble@yahoo.com), January 11, 2002.

Bob,

I've used my Jobo since 1994 with wonderful results.

With color, I've always had great luck just following the instructions E6 Chemistry instructions to the letter.

With B&W, I believe you HAVE TO TEST for optimum results. I've done hundreds and hundreds of runs using everthing from D-76 to Morley Baer's Citric Acid Pyro formula in formats ranging from 35mm to 8x10.

Most of my developing (in all formats) has been HP5 in PMK, which is very diluted and requires filling the Jobo drums as completely as possible. And for plus development with PMK, sometimes I've had to resort to split development, meaning draining at half the development cycle and refilling for the second half with fresh soup. This is due to the rapid oxidation of pyro devlopers and probably wouldn't be a factor with D76, etc.

When you do your testing, be aware that developing one sheet in a half liter can produce a different result that developing five or ten sheets in the same amount of chemistry. You'll find it's easiest to get your times/volumes down precisely if you can use the same volume of chemistry and about same number of film sheets each time in a Jobo.

But hey, if this was supposed to be easy there'd be a digital Linhof ;-)

-- David Haynes (studioblsp@mindspring.com), January 12, 2002.

Lately, I've been using Zonal-Pro Gamma for 4x5, 5x7 and 8x10 B&W, and have been quite pleased. Films: TMax 100 and 400, and Arista 400 (same as Ilford HP5+). Dilutions ranged from 1:1, to 1:7 to 1:21, using 100ml of developer in each case. With Arista and TMax 100 film I get good results at all dilutions. One batch of 8x10 TMax 400 was horrible at 1:21, but quite fine at 1:7 and 1:1. That processing run had Arista 400 as well as TMax, due to my confusion. The Arista came out perfect, so I'm wondering if my Tmax 400 had been sitting around too long in the film holder and 'aged'. An image is discrenable holding the neg up to the light, but the whole negative is yellow-orange-tan color.

-- Roger Urban (roger_urban@yahoo.com), January 13, 2002.