Developing on a B’s Processor with a Jobo

The Jobo development tank sitting on top of a 3D printed processor
The extended Jobo tank set up sitting on the processor.

Though I’m only a year into developing my own film, my wife and I shoot enough film to justify some kind of a processor. Though I have Jobo tanks, developing in my small bathroom means I can’t get a big Jobo developer. So when I found the B’s Processor by Benoît Barbé it seemed like a great solution.

Waves crashing on rocks.
Gold 200, 120. The 1530 extended setup lets me develop 6 rolls of 120 in one go.

It’s compact, flexible, and fits on the card table I use for my chemicals. And the price is pretty good too. The magnetic tracker lets the processor rotate the film back and forth for even agitation. My results with it so far have all been great, and blasting through rolls feels great.

A gray cat sits in a window looking through curtains toward the camera.
ColorPlus 200, 35mm. You can develop five rolls of 35mm in one shot using the processor.

However by default, it’s set up for a Paterson tank. While I do have a Paterson tank and a similar AP tank, I have found that the Jobo is a better fit for my workflow. I like the way the reels work. I like how leak proof the tank is. And the ability to extend the tank makes it easy to store it all.

So how do I use it with the Jobo?

First, I needed a Jobo 1530 extension module and a bunch of Jobo 1500 reels. The smaller Jobo 1510 and 1520 tanks don’t fit on the processor without the small tank support you can order. I prefer the extension approach, because I’m mostly interested in using the processor for large quantities of film, but I have used the small tank support with great success as well.

If you are using the 1530, Bounet Designs makes a set of mini-wheels. These allow the extended tank to sit evenly across the processor, which prevents it from bouncing around.

Closer look at the Jobo tank and processor demonstrating the alignment.
A close-up look at the setup.

To set it up, the bottom orange lip sits on the wheels. Now you set two rubber bands where the large wheels meet the tank, just below the top orange lip. Finally, position the magnet tracker so it lines up with the target. I then used masking tape to temporarily hold the tracker in place, while I fixed it down with the provided stickers. I used some rubber bands to hold the sticker on while the tracker took the shape of the Jobo tank and the sticker got a permanent hold (I guess try not to get it wet during this time). Finally, I used gaffer tape to hold it all down and give it that all important DIY aesthetic.

A snowy Colorado town with a sign for a pinball gallery.
Lomo 800, 35mm. The rotary tank makes developing all the film you shot on a trip easy.

As far as development, probably best to reach out to the manufacturer of the developer you use and see what changes to make to your process. The Massive Dev Chart’s temperature converter can do rough calculations for how to adjust black and white developers for constant agitation, if you’re willing to test it out yourself. Flic Film’s C-41 chemistry comes with instructions on how to adjust times when using processors and their customer support is prompt and helpful with any development questions.

A woman in a red beanie frames up a shot with a film camera.
Lomo 800, 35mm

Another thing to keep in mind is the chemical quantities. You can use less chemistry when doing rotary development. Jobo tanks list the chemical amounts on the side of the tank for both inversion and rotation. Add the rotation quantities for the main tank and the extension tube and you have the rough amount of chemicals you’ll need; the 1520+1530 requires only a minimum of 570mL of chemicals. You may want more to ensure consistent development, personally I use around 1000mL, which is still easier to have on hand than the 1275mL required to do inversion development in the same tank.

And the best part of Jobo tanks is that I can easily remove the extension and do inversion development for smaller batches or when I want to push film. If you also buy the small tank support, you can use the same rotary set up in both configurations.

So overall, I’m a big fan. If you do follow down this road, I’d recommend starting off with a few test rolls just to be sure you’re everything in your setup is working with it before you throw important rolls at it.