Jobo 2500 processing

[Luca Merlo]

After several years and few thousands B&W films (35 mm and 120) developed with Paterson tanks by inversion, I will soon have to develop 4 x 5 negatives with a Jobo 2500 series tank. Since I tend to be very skeptical about the consistency of the developing by rotation, I was wandering if I can get good results with the inversion method (I am using Rodinal in a 1+50 dilution that is very effective and inexpensive so the consumption of developing agent is not an issue for me). I am wondering now if the Jobo 2500 model that can accommodate one reel offers enough displacement for the proper agitation of the liquid inside the tank or if I have to purchase the tank which can accommodate two reels (loading it with only one reel), that will certainly give the developing solution a good agitation. Moreover I would like to know if anyone had experience with Forte 200 film developed in Rodinal (I find that the 120 rolls give very good results).

[Steve J Murray]

Luca, I recently started using the single tank Jobo 2500 series tank with 4x5 film too. I haven't tried the inversion method. I have had even development by simply filling the tank half full and hand rotating on some rollers (furniture castors on a board). I roll 15 sec before changing direction at a nice comfortable pace. Its not as bothersome as it sounds. Most people will recommend getting a Unidrum motorized base, which apparently works quite well for this. Anyway, my negs so far have been evenly developed, even in smooth sky regions. I used a homemade developer at 8 to 10 minutes after presoak of a couple minutes.

[Nick_3536]

Rodinal may be cheap but the one real tank needs around 1.5 litres of developer if you try inversion. It maybe a little less but not a lot less. Now that's for a max of six sheets. Or for just one sheet.

Using a motorbase is much better IMHO but it won't work with the one reel tank. You need at least the tank that can handle two sheet film reels.

I can't see how any human can be more repeatable then my motorbase. It rotates exactly the same way all the time. It doesn't day dream. Get bored. Lose track of time. It's a machine and does everything exactly the same way every time. Now I've heard some claim they think it's better to be random but I'm not sure I understand that.

To answer your main question. I don't think the smallest tank really provides enough head space.

[Eric_4595]

Luca - I use the 2500 series one reel tank exclusively for 4x5. I usually use Rodinal 1:50 as well with inversion. I had a bit of trouble at first using the tank while I played with the amount of developer to use, and settled on 1500 mL. Anything less than that runs the risk of underdevlopment on the film edge, and anything more than that won't allow proper agitation. With that in mind, I haven't had any issues with uneven developing. It is a lot of solution, but Rodinal is cheap! By the way - loading it is difficult at first, but it becomes second nature very quickly.

[jose angel]

Luca, I have used the 2500 tanks to develop 4x5´s by inversion before buying the processor... one of the best decisions I have taken. The processor gives far more consistent results that the inversion system. I have never experienced uneven results with it, and I find that is the only way to have real accuracy in the film development process.

If you like to process by inversion with a 2500 series drum and the 2509n reel as I did in the past, you can do it sucessfully. There are little but enough space for the solution displacement. Just check the minimum needed solution with some adhesive electrical tape at the border of the opened drum with sheets and the reel inside... I´m also a Rodinal fan...

[Deniz]

Luca- I can't comment on the jobo developing question since i am a tray developer guy but i use Arista.edu 200 and 400 in 4x5 and 8x10 sizes and i beleive it is the same film as fortepan 200 and 400. I develop in 1+25 rodinal and i quite like the results. I print on Azo paper and contact prints are quite beautiful.

[Henry Ambrose]

By the larger tank. If you look at a loaded reel placed in a 2500 single tank you'll see that only when the tank is completely full is the film covered, leaving no room for proper agitation.

[jose angel]

Henry, how many room is needed for proper agitation? Don`t you consider the upper side of the drum, up to the cap, as an empty space?