Working with a rotary processor
I am in the process of acquiring a Beseler motor base and I've been trying to find some literature that will let me know exactly what kind of changes I would have to do to compensate for this.
I've read that i can expect to lower my developing time by up to 15%, but the directions that came with my Tetenal c-41 kit has in fact no time variation marked to account for this. What gives?
Also, I've heard that with constant agitation, since the chemical exhaustion is reduced, i can use half of my solution (250ml), unfortunately, this was anecdotal, and I can't find evidence to support this anywhere. Would this also apply to black and white? I will be processing a bit of 120, but mostly 220.
I apologize in advance if this has already been address in the archives, but I couldn't find something non-jobo related that specifically addressed my problem.
You will get many differing replies regarding rotary developing, Jobo or otherwise.
I myself have been rotary processing with a Jobo CPE2 for over 20 years and have never worried about extending or contracting development times. This is with C41, E6 and many other B&W developers.
C41 is a special case (I have been informed on APUG) in that there is a very short development time, which from my experience is true and varying from the development time by any great degree will bring about changes.
The perfect world development for C41 is 37.77ºC for 3'30", how close you can come to that with your equipment, will always be open. The best idea is to work out what is feasible and workable for your system, then stick to it.
I myself have a lift on my Jobo, with C41 I start dropping the developer at 3'20" this takes about 7 seconds to do, I then drop the lift in the remaining few seconds and start pouring in the next solution I'm within a few seconds of 3'30". I'm not dead on, but reasonably close. It works very well for me so I use this method all of the time.
Consistency is paramount when developing colour, just ensure you are as close as is possible to what the manufacturer of your kit suggests. If this works, and more importantly, works well, just keep on doing the same thing.
Regarding solution capacity, you must ensure that the amount of solution you use with rotary developing is adequate for the number of films and/or, the amount of required developer.
For instance, if your C41 kit suggests that the 1 litre kit will develop 8 rolls of 135 x 36 frame film and you had a drum that allowed you to develop 4 rolls of film in 500ml of developer, if you did it with rotary agitation, then it is simple. You would use two lots of 500ml doing two lots of developing, with four rolls at a time.
Welcome to APUG and rotary development.
Last edited by Mick Fagan; 10-17-2009 at 02:02 AM. Click to view previous post history.
I use the Jobo 2300 ATL. Here is the bottom line that I found.
After many different results with each different film, NOT just different chems, i.e., C-41,E-6,BW, I had to begin a log. I can post a draft for you to see and customize to your own. (Excel file)
For example: in the C-41 world, Kodak's BW400CN is perfect at the plain old "tank" rated dev time in my jobo, but Tri-x needs a 10 pct reduction every-time, This I know from beginning with a 5pct reduction. Then Fuji 800z needs 15 pct reduction time.
Same for B/W and E-6. This is the only way to nail it for your processor. It's not hard and after awhile you will have a "bang-on" list.
P.S. When doing this or even without logging, follow Kodak (for example) pdf's on that specific film. NOT on-line i.e., Massive Dev Chart. Then stick to it.
A great many times the film mfr's will include Rotary dev times that I've found perfect for me.
I had always thought that C41 needed 3 mins 15 secs and that rotary processing made no difference to the times. It is certainly what all the kits I have used, said. Isn't this what professional mini-labs use as the time?
It appears that Tom has nailed his time for Fuji 800z down to about 2mins 45 secs( 195 secs minus 30 secs) but if you've never tried C41 rotary processing I'd be inclined to stick to 3mins 15 secs and see what you get.
B&W seems to be a different case and unless you use a 5 minute pre-wet then Ilford recommend a 15-20% reduction but Ilford do not recommend a pre-wet. John Tinsley who wrote a book about rotary processing used a pre-wet and found that for B&W the times he required for rotary was the same as for inversion agitation.
However for C41 he stuck to 3 mins 15 secs. It's up to you but I'd be wary of varying C41 times until you have tried the kits manufacturers'times
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I had several King Concept rotary processors in my labs over the years. I've used them for E-6, B/W, C-41 in formats from 35mm - 8x10 sheets. Every process has compensations from standard manufacturer manual tank development times. Compensations range in process times due to agitation types primarily. Each process manufacturer will provide specific times at specific temps for the type of equipment you are using. Use the film and chem manufacturers data sheets and follow their specific instructions for your equipment type. For example, on my existing King Concept machine I simply use the program for a specific process like C-41, if the process has changed or is a different manufacturer since the program was written I make manual corrections according to the latest data sheets. It's not difficult to get things right if you pay attention to details. In your case you are running a constant agitation rotary base so you would look at the chem manufacturers data sheet for all info pertaining to a constant agitation process. Determine your drain and fill times by practicing with your drum. Then just stabilize your temps and you are good to go with everything figured out and ready. Run some test film first. Tweak later if you need to but not likely if you followed instructions. If you decide to do a fair amount of color work then get a densitometer, run some process control strips and plot them. It will tell you everything you need to know about your process and technique and will stop all the guessing. Good luck.
I would be interested in your findings in Excel format....Cheers Dave
Originally Posted by dwdmguy
Thanks all for the warm welcome and information.
Originally Posted by Mick Fagan
Concerning chemical capacity; This page by Jobo establishes that their 1520 tank only requires 240ml for working with a rotary base.
Now, I don't know if there is something special about the way these tanks are built, but i want to know if this if chemical reduction is something common that happens when using constant agitation.
At this time, I only own a couple Paterson IVs. Is it possible to also reduce my solutions down to 250ml and use it on the Beseler base? I'd like to get started as fast as possible since i already have a heavy backlog, instead of waiting for a 120/220 drum to show up on ebay/CL.
There is a volumetric and a chemical side to it.
Volumetric: the bath volume must be large enough to cover the inner end of the film on the reel. But small enough not to leak out via the filling tube.
Chemical: that low volume must be sufficient to contain enough agents to process the film without exhaution of agents. In special cases that would mean using a larger drum and adding empty reels to allow more bath volume with the same amount of film.