MOD54 vs. Jobo 2509n minimum developer for 6-sheet inversion processing

[Simos Xenakis]

I'm planning to start out with hand-inversion processing of 4x5 sheet film and am stuck between the MOD54 (in a Paterson 3-reel tank) vs. the Jobo 2509n (in a 2520 2-reel tank).

Aside from the additional flexibility/modularity (and easy 4x5 loading) of the Jobo, and assuming my inversion technique would be identical for both systems, why is it that the Jobo, which seems to be a smaller tank (accepts 2x 35mm reels), requires nearly 1.5L of developer for inversion processing whereas the MOD54 requires only 1L in a (seemingly) larger 3-reel tank?

Additional questions:
a) can you adjust the amount of developer downward when processing (by hand inversion) less than 6 sheets of film in each of these two tank systems? Say, if doing 4 sheets, or if doing 2 sheets, rather than 6? Do you still have to use 1L for MOD54 and 1.5L for 2509n?
b) how does the above answer change with rotation processing on the Jobo? The website says: "High efficiency; run as few as two sheets of 4X5 with no waste of chemistry." Having a hard time understanding what that means. Isn't the minimum volume for rotary processing 270ml? According to what I've read here, that is the same minimum volume needed for 6 sheets. If so, that means the tank is NOT efficient for 2-sheet processing, since you'd be able to get 4 additional sheets out of the solution if you maxed out the 4x5 reel. What am I missing about their claim that it's a "high efficiency" tank?

I am a complete newbie (first post here at LFPF!), so I'm sorry if I'm missing something super basic. Tried researching this topic but couldn't find an answer to these nagging questions.

[Leigh]

Regardless of the method or equipment or technique used...

You must ALWAYS use at least the minimum amount of developer per roll as specified by the developer maker.

If a 100ml bottle of the concentrate is spec'd to develop 10 rolls of film, then you need 10ml per roll.
This minimum applies to the volume of concentrate, regardless of the dilution used.

Using less runs the risk of underdevelopment or uneven development.

- Leigh

[Graham Patterson]

The MOD54 uses a tank that is closer to the Jobo 1500 series in size. The 2500 series have a larger diameter, and the film is positioned close to the outside. For inversion and given the same tank height, the 2500 has more volume. If you were doing a 35mm film in a Paterson spiral you would need 290ml minimum. That's about 54 sq. in. for a full 35mm film. 6x 5x4 is 120 sq. in. Provided, as Leigh says, your active ingredients are enough, the 2509 in rotary mode is pretty efficient. Chemistry is a lot cheaper than the film.

Using a 2500 series tank for inversion is possible, but it is a bit of work, and unless you are using stock or replenished developer it might be expensive. You have to fill a lot of empty tank space.

For inversion, you have to use enough developer to cover the film at rest. There's no way around that.

[vdonovan]

If you're not committed to six sheets, you might also check out the SP-445, which handles four sheets. Super compact, efficient, and the easiest to load. I love mine! https://shop.stearmanpress.com/produ...cessing-system

[Michael W]

Additional questions:
a) can you adjust the amount of developer downward when processing (by hand inversion) less than 6 sheets of film in each of these two tank systems? Say, if doing 4 sheets, or if doing 2 sheets, rather than 6? Do you still have to use 1L for MOD54 and 1.5L for 2509n?

I have a MOD54, which I like, but you have to use one litre no matter how many sheets you are doing. For me that's not a problem as I usually have four or more sheets to do.
That new SP-445 system does look interesting.

[Simos Xenakis]

Regardless of the method or equipment or technique used...

You must ALWAYS use at least the minimum amount of developer per roll as specified by the developer maker.

If a 100ml bottle of the concentrate is spec'd to develop 10 rolls of film, then you need 10ml per roll.
This minimum applies to the volume of concentrate, regardless of the dilution used.

Using less runs the risk of underdevelopment or uneven development.

- Leigh

Thanks, Leigh. That's helpful info to keep in mind. I'm new to film photography in general, so I'll be sure to check the developer spec minimum as my first concern and always use at least that amount unless my processor calls for an even greater volume of chemistry, which would be the case with both of these systems doing manual inversion. But yeah, in the case of rotary processing which utilizes very little chemistry, I'll have to remind myself to always check the developer mins first.

[Simos Xenakis]

The MOD54 uses a tank that is closer to the Jobo 1500 series in size. The 2500 series have a larger diameter, and the film is positioned close to the outside. For inversion and given the same tank height, the 2500 has more volume. If you were doing a 35mm film in a Paterson spiral you would need 290ml minimum. That's about 54 sq. in. for a full 35mm film. 6x 5x4 is 120 sq. in. Provided, as Leigh says, your active ingredients are enough, the 2509 in rotary mode is pretty efficient. Chemistry is a lot cheaper than the film.

Using a 2500 series tank for inversion is possible, but it is a bit of work, and unless you are using stock or replenished developer it might be expensive. You have to fill a lot of empty tank space.

For inversion, you have to use enough developer to cover the film at rest. There's no way around that.

Graham, the way you framed it makes sense. So the Jobo is simply much fatter (even though it's shorter). And the "girth" allows it to be super efficient at rotary since only a small amount of chemistry is required to slosh through the film which sits closer to the outside of the tank. Paterson, in the pics, just looked like a larger tank overall though, and the fact that it can handle 3 rolls of 35 as opposed to the Jobo's 2 rolls threw me off. I guess in terms of the 4x5 minimum specs I listed above (1L for MOD54 / ~1.5L for Jobo), it must also have something to do with the MOD54 being a chunkier piece of plastic which occupies more of the volume in the tank, making it easier to fill to the top and cover the film. The 50% greater min volume is still surprising but it makes more sense now.

Thanks for helping me work through this!

[Simos Xenakis]

If you're not committed to six sheets, you might also check out the SP-445, which handles four sheets. Super compact, efficient, and the easiest to load. I love mine! https://shop.stearmanpress.com/produ...cessing-system

I had looked into that one but came across a fairly recent thread (forgot which website, APUG maybe?) where people were having issues with bent film holders leading to streaking on the back side of the film. The designer was trying to help them out but I don't think the issue was ever resolved. Plus, being able to process 35mm using the same equipment really appeals to me.

[Simos Xenakis]

I have a MOD54, which I like, but you have to use one litre no matter how many sheets you are doing. For me that's not a problem as I usually have four or more sheets to do.
That new SP-445 system does look interesting.

Out of curiosity, what is considered to be a decent efficiency of chemistry per slide when it comes to inverting 4x5? I guess the SP-445 sets the mark at like 120ml per slide?

[Halford]

Here are the Paterson and the Jobo 2500-series next to each other. In a picture with no context the Paterson can look bigger because it's taller relative to its diameter, but in fact the Jobo is bigger in every dimension.