JOBO RPM

Bruce Osgood

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• Aug 18, 2006

• #1

I haven't felt I have a problem but would like some clarification on rotating speed.

My Jobo CPE 2 with lift has but one speed: 75 RPM.

Some film developers mention using the 'slow' setting on the Jobo.

Is 75 RPM 'slow' or 'fast' and should suggested development times be compensated for with 75 RPM?

Thanks,

 

hka

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• Aug 18, 2006

• #2

Bruce,
for the 2500 tanks its the right RPM. The 3000 tanks need a lower speed, max. 50 RPM. But for sofar I know the 3000 tank won't fit on the CPE. I use the 75 RPM for years with any problems and about 40 RPM for the 3000 tank on the CPP. That's also what Jobo recommends.

 

Baxter Bradford

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• Aug 18, 2006

• #3

I moved from ATL-1000 with 75 rpm to an ATL-2300 which offers 25, 50 or 75rpm. I tried using 25rpm but got underdeveloped negs with Pyrocat HD. Sandy King advised using 75rpm and the situation was rectified. Full details in the APUG archive.

I think the figure was 20% different, but not having access to any sensitometry cannot be more specific.

 

Robert Hall

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• Aug 18, 2006

• #4

I use 25 rpm on 12x20 negs and boost the amount of developer at that speed. It works well. I use 50 rpm on the expert drums.

I will have to give the HD a try here soon and see what the results are.

 

Bob F.

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• Aug 18, 2006

• #5

75 RPM is the Fast speed. Other CPE2's like mine have two speeds - approx 75 RPM and approx 30-40 RPM. In general, from my reading, the slow speed is not recommended for general use. Jobo used to recommend it but has apparently since changed it's mind.

Cheers, Bob.

 

Ole

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• Aug 19, 2006

• #6

I've got one of the old CPE's with two speeds - "screaming fast" and "leisurely".
I use the slow speed for B&W, and the fast one for colour.

On another note my instruction book mentions developing large sheet films in paper drums, so that's what I do. 9x12cm and 4x5" in the 2509(?) spiral, and 5x7" up to 12x16" in 28xx series paper drums. Guess what: Even the 5x7" slides come out great!