JOBO ATL-3 at 20 C Stock vs 1+1 and Development Time Adjustments

vicb · Tuesday at 4:55 AM

Hello everyone,

I’m about to start running a JOBO ATL-3 and would appreciate some insight from those with long-term experience using JOBO processors at 20 °C.

For context: I’m not new to film processing. Until now, I’ve mainly worked with dip-and-dunk lines, using Ilford chemistry at 24 °C, so I’m familiar with process control and consistency. However, moving to a rotary JOBO workflow means re-evaluating a few variables, and I want to set things up correctly from the start.

I have a few specific questions:

Stock vs 1+1 in JOBO rotation
Do you generally recommend using stock solutions rather than 1+1 dilution for rotary processing in the ATL-3?
My main concern is maintaining maximum consistency and repeatability over time, rather than saving chemistry.
Development times vs Massive Dev Chart
I’ve checked the Massive Dev Chart as a baseline, but I’ve seen several discussions suggesting that JOBO rotary processing requires reduced development times compared to inversion or dip-and-dunk.
- What percentage reduction do you typically apply at 20 °C?
- Is there a commonly accepted starting point (e.g. 10–15%) that you’ve found reliable?
Stability over experimentation
My goal is to establish stable, standardized development times rather than constantly adjusting per roll. From your experience, is it better to:
- Lock in one conservative reduction factor and stick to it, or
- Fine-tune per film/developer combination when using JOBO rotation?

Any recommendations based on real-world ATL-3 use would be very helpful. I’m especially interested in approaches that prioritize process stability and predictable negatives over marginal speed or economy gains.

Thank you in advance for sharing your experience.

koraks · Tuesday at 5:30 AM

vicb said:
Stock vs 1+1 in JOBO rotation

Please specify the chemistry (developer) used.
Regardless, I'd say this is up to you - whichever you prefer.

vicb said:
Is there a commonly accepted starting point (e.g. 10–15%) that you’ve found reliable?

The 15% figure you mentioned seems to be a good starting point, but as always, nothing beats proper testing if you're after a very specific result in terms of gamma or curve shape.

As to #3, I'm not entirely sure what you're referring to. In general, each film/developer/EI/agitation/gamma/temperature combination will have a unique development time associated with it. You can control this as tightly as you want, depending on your needs.

Given your mention of dip & dunk, am I correct in assuming you're running a commercial operation, offering development services for external clients?

You phrase your questions as specific to the Jobo ATL-3 system, but in my view, they're mostly generic questions and only to an extent specific to continuous rotation development. None of it is really specific to the ATL-3. It may help for you to widen the scope of your search beyond the ATL-3 since it's not really that relevant a choice in this regard. It would be different if your questions were about maintenance and repairs on this particular machine, of course.

vicb · Tuesday at 5:42 AM

koraks said:
Please specify the chemistry (developer) used.
Regardless, I'd say this is up to you - whichever you prefer.

The 15% figure you mentioned seems to be a good starting point, but as always, nothing beats proper testing if you're after a very specific result in terms of gamma or curve shape.

As to #3, I'm not entirely sure what you're referring to. In general, each film/developer/EI/agitation/gamma/temperature combination will have a unique development time associated with it. You can control this as tightly as you want, depending on your needs.

Given your mention of dip & dunk, am I correct in assuming you're running a commercial operation, offering development services for external clients?

You phrase your questions as specific to the Jobo ATL-3 system, but in my view, they're mostly generic questions and only to an extent specific to continuous rotation development. None of it is really specific to the ATL-3. It may help for you to widen the scope of your search beyond the ATL-3 since it's not really that relevant a choice in this regard. It would be different if your questions were about maintenance and repairs on this particular machine, of course.

I’m planning to use D-76 developer; up until now, I’ve primarily worked with Ilford DD. While I haven’t set up the JOBO machine yet, I’m making sure I understand the correct programming times. Most of my experience has been with a dip-and-dunk setup, so I’m trying to mindfully adjust and adapt to the JOBO process to ensure everything is done perfectly.

And yes, I run a commercial operation and wanted to check if that still allows me to ask questions here. I apologize if that isn’t permitted and hope I haven’t inadvertently broken any rules.

koraks · Tuesday at 5:46 AM

vicb said:
I run a commercial operation and wanted to check if that still allows me to ask questions here.

No worries! It's fine, really. I asked mostly because it means that you're dealing with clients who may have varying expectations with regard to film processing. Most will likely not care one way or another as long as they can use the negatives for scanning/printing without much trouble. There may also be clients with very specific requirements. If that's the case, some more testing may be involved to meet their requirements. If you're only dealing with clients in the former category, I wouldn't make things too complicated and settle on a select few processing times for the common films you see a lot and just ensure that the development will yield acceptable negatives.

vicb · Tuesday at 6:07 AM

koraks said:
No worries! It's fine, really. I asked mostly because it means that you're dealing with clients who may have varying expectations with regard to film processing. Most will likely not care one way or another as long as they can use the negatives for scanning/printing without much trouble. There may also be clients with very specific requirements. If that's the case, some more testing may be involved to meet their requirements. If you're only dealing with clients in the former category, I wouldn't make things too complicated and settle on a select few processing times for the common films you see a lot and just ensure that the development will yield acceptable negatives.

Okay, thank you so much - I really appreciate your answer! Yes, I do work with clients, many of whom use the negatives for enlarger printing, while some only need scanning. I want to make sure everything comes out as good as possible. Just to make sure I understood correctly: you’d recommend sticking to the standard development times at first, then running some tests to see if I should slightly reduce the dev time until I achieve consistently good results, and then stick to that for most development - except for clients who have specific requirements.

koraks · Tuesday at 6:12 AM

Yes, that would be my approach. Personally I'd run some test rolls of my own with films that you see a lot in your lab (probably stuff like HP5+, maybe some TriX and/or TMAX, perhaps some fomapan) exposed by yourself in a reasonably controlled manner. See if that results in negatives that print for the most part around grade 2 or so for a normal contrast scene. If you hit close to that mark, your clients should be able to use the film for darkroom printing and scanning.

vicb · Tuesday at 6:16 AM

koraks said:
Yes, that would be my approach. Personally I'd run some test rolls of my own with films that you see a lot in your lab (probably stuff like HP5+, maybe some TriX and/or TMAX, perhaps some fomapan) exposed by yourself in a reasonably controlled manner. See if that results in negatives that print for the most part around grade 2 or so for a normal contrast scene. If you hit close to that mark, your clients should be able to use the film for darkroom printing and scanning.

Thank you so much! This is really helpful, and it’s exactly what I’m going to do - run test rolls with the films we get the most and see how they turn out. I really appreciate your guidance!

koraks · Tuesday at 6:18 AM

Great! Please keep monitoring this thread for additional responses; there may be contrasting or contributing viewpoints that can help you make the best decisions for your particular use case.

vicb · Tuesday at 6:23 AM

koraks said:
Great! Please keep monitoring this thread for additional responses; there may be contrasting or contributing viewpoints that can help you make the best decisions for your particular use case.

Thank you, will do!

Stephen Benskin · Tuesday at 12:13 PM

vicb said:
I’m planning to use D-76 developer; up until now, I’ve primarily worked with Ilford DD. While I haven’t set up the JOBO machine yet, I’m making sure I understand the correct programming times. Most of my experience has been with a dip-and-dunk setup, so I’m trying to mindfully adjust and adapt to the JOBO process to ensure everything is done perfectly.

And yes, I run a commercial operation and wanted to check if that still allows me to ask questions here. I apologize if that isn’t permitted and hope I haven’t inadvertently broken any rules.

Kodak tends to have starting times for different development methods including rotary tube.

I know the times are for full strength, but it gives you an idea and you can begin by extrapolating the difference between the full strength and 1:1 times using a different method.

Craig · Tuesday at 12:52 PM

Depending on how much film I'm running in the tank, I tend to use full strength solution simply so I can ensure that I have a sufficient volume of chemistry to properly develop the film and not exhaust the chemistry.

I find this more important for the Expert drums that hold sheet film, as it can be possible to load more film than the minimum volume of chemistry can process. So always keep in mind the capacity of the solution.

vicb · Wednesday at 3:59 AM

Thank you very much Stephen and Craig!

JOBO ATL-3 at 20 C Stock vs 1+1 and Development Time Adjustments

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