Jobo questions

[stevierose]

Hello--I'm about to develop some BW film using a Jobo Silverbase, which is basically a Jobo without tempering ability which is fine with me. It's been a couple of decades since I last used a Jobo. The recommendations used to say to pre-wet the film and to reduce the development times used for standard manual agitation by 15-20% when using a Jobo. That was a long time ago and films and recs may have changed. What do you folks do now when using your Jobo or other rotary processor? Many thanks!

 

[trix4ever]

I use a Jobo expert 3013 on a Beseler motorised base for 5x4. Basically the same thing.
Yes, I do find a pre-rinse helps and I ran a series of tests and found for my preferences with tri-x and D76 1:1 I needed to reduce the dev time by 15%.
BUT that is with my water, my thermometer and my preferred contrast.
You will have to run a few tests to achieve what you want to achieve, for instance are you developing to scan or to wet print?
With sheet film I find this gives me perfectly even skies and a full range of tones.
It's been a while since I rotary processed roll film but the principle is the same.

5x4 tri-x in D76 in Jobo rotary tank

 

[Benjamin Marks]

That sounds right. To state the obvious: the decrease in time is to make up for the fact that the film is constantly coming into contact with new developer as the drum rotates, compared to intermittent agitation (one option with the steel tank non-rotary choice, or a dip-and-dunk tank approach). The pre-soak ensures that with those short development times, all the surface area of the film is getting access to the developer without any delay. This always worked well for me. Just sold my JOBO ATA auto processor this weekend. Sniff/sob. End of an era.

 

[Cascadilla]

Hello--I'm about to develop some BW film using a Jobo Silverbase, which is basically a Jobo without tempering ability which is fine with me. It's been a couple of decades since I last used a Jobo. The recommendations used to say to pre-wet the film and to reduce the development times used for standard manual agitation by 15-20% when using a Jobo. That was a long time ago and films and recs may have changed. What do you folks do now when using your Jobo or other rotary processor? Many thanks!

I have developed thousands of sheets of 4x5 in a JOBO 2500 series 2 reel tank (12 sheets of 4x5) on a Unicolor roller base. When I first got it my first batch was quite disappointing--lots of streaks. I called JOBO and got some advice: dilute out your developer so that the developing time is at least 10 minutes and take the tank off the roller once per minute and invert the tank 3 times in 5 seconds. Doing that made the streaks disappear and they never came back. It took some testing to work out a custom dilution for HC 110, but it was problem free after that. I also agree with a pre-soak--it does help with developer soaking into the film and has the added benefit of getting the tank and film to your developer temperature. I have never developed roll film in this tank--that I have always done in stainless steel tanks (Kinderman) with Hewes reels.

 

[Glenn2]

Thanks for that information Cascadilla. I’ve got the exact same setup, but haven’t used it yet. Will probably start by using 1:1 D76 as I’ve got lots and chemistry to make a lot more. Have even wondered how a two bath developer like split D76 would work in a Jobo?


Your hints are appreciated.

 

[trix4ever]

I guess the Silverbase automatically changes rotation direction but on a simple motorised base I also lift the tank off every minute, shake it and put it back facing the other way.
I also agree that the longer the process the better, so diluted developer is a good idea, recently I've been using Ilford LC29.

 

[Cascadilla]

I guess the Silverbase automatically changes rotation direction but on a simple motorised base I also lift the tank off every minute, shake it and put it back facing the other way.
I also agree that the longer the process the better, so diluted developer is a good idea, recently I've been using Ilford LC29.

The Unicolor roller base I have is motor driven and reverses direction every 3 seconds or so. It still required the tank to be taken off and agitated vertically every minute to get rid of the streaks.

 

[stevierose]

I use a Jobo expert 3013 on a Beseler motorised base for 5x4. Basically the same thing.
Yes, I do find a pre-rinse helps and I ran a series of tests and found for my preferences with tri-x and D76 1:1 I needed to reduce the dev time by 15%.
BUT that is with my water, my thermometer and my preferred contrast.
You will have to run a few tests to achieve what you want to achieve, for instance are you developing to scan or to wet print?
With sheet film I find this gives me perfectly even skies and a full range of tones.
It's been a while since I rotary processed roll film but the principle is the same.

5x4 tri-x in D76 in Jobo rotary tank

Gorgeous!

 

[rolfe]

The five minute pre-wet eliminates the need to modify processing times by 15%, as the pre-wet offsets the faster processing time of continuous agitation.

 

[DownUnder]

In my time I've used all the Jobos. I resisted buying one, mostly due to the ridiculously high prices in Australia, until 2004 when a retailer in Melbourne had a sale on Jobo Duolabs. This has to be THE most basic unit that company ever made, but for me it did (and still done) all I need for home processing films - I tried it for prints but after a few spectacular failures decided to stay with my three trays and a safellght.

The Duolab is spectacularly good. It used what has been described as a basic coffee machine element heater (this is entirely anecdotal, BTW, but it's a good story) with three temperature adjustments.

The only problem I've ever had with it was bromide drag in the first few films I processed. After a bit of snooping about online I resolved this by diluting my developer (I was then using Kodak D76 or Ilford ID11) 1-1. After which boom! bang! no more drag. Problem solved.

Also prewetting the films. This has to be the best piece of advice anybody could ever give.

My Duolab takes a few minutes to set up and a little time to warm the water baths to the desired temperature, and it does all I want it to without fuss or bother. I liked it so much that a year later I bought the last remaining Duolab from the same shop, as a backup unit. In 2020 I sold my older/most used unit for what I paid for it (+/- AUD $400 IRRC) to a friend who was setting up a darkroom. We get together for photo gossip and drinks now and then, and she still thanks me for having sold it to her. Which to my thinking, says it all for the Duolab.