Continuous Agitation?

[I.M.Gadget]

Hey all
I bought an 8x10 camera a little while ago and was developing single sheets in a Stearman SP-8x10 that I had for my 4x5 and 5x7. I recently bought a Jobo 3005 and a Beseler motor base. Is this considered continuous agitation as the film is not technically immersed in developer all the time? I'm fairly new to this and couldn't find an answer. Lots if 'how' but not 'how long'.
Thanks
G

[Michael R]

Continuous agitation means the film and/or developer is never still. Rotary processing such as what you are doing would be an example. Any setup in which the film is not fully immersed in/covered by the chemicals basically has to involve continuous agitation. If the film is fully immersed/covered, agitation can be either continuous or intermittent. Examples of this would be inversion tanks, deep tanks, trays.

[xkaes]

Rotary processing is basically continuous agitation, even though, on each rotation, only 1-2 inches of the film is actually in the developer for a second. With tray development, the film is always in the developer -- regardless of any agitation.

I process my 4x5 film (B&W and Color) in rotary drums, in a temperature controlled water bath (Colourtronic). I find it gives very consistent results, but there are several things to keep in mind.

With constant agitation, you need to adjust your developer time/temperature/dilution/etc. to get the results you want -- a topic too lengthy to discuss here. In short, continuous agitation produces different results, so you need to test and adjust as needed -- ISO, developer time, temperature, dilution, etc. I generally use a lower ISO, higher dilution, and longer development time.

Also different drums work with sheet film in different ways. Some have clamps/tabs/holders of some sort to keep the film in place. Others, like mine, uses different sorts of ridges.

These can create problems. The clamps/ridges can create turbulence around the clamps/ridges leading to over development of the film close to the clamps/ridge.

And another problem specific to ridges deals with developer PH. Most developers have a high PH and are slippery. If you pour in (or out) the developer too fast, the film can move out of place in the tube -- and cover up other sheets in the drum!!! Not good. On my drums, there is a section without ridges -- so there will not be any film in that area. I always place that part of the drum on the bottom when I'm adding or draining chemicals or water -- and I tilt the drum SLOWLY -- so the sheets of film will not slip out-of-place.

Another possible problem with some drums is that the film can stick to the inside of the tube. Mine have tiny ridges to prevent this. If the film has a backing that is normally removed during processing, this will not be removed if the film is stuck to the tube. You can solve this problem by placing the film back in the developer AFTER complete processing with the lights on -- or get a better drum.

It takes a bit of work to get it right, but I think it's worth it -- and you should be running the same film tests even if you use tray processing.

[Alan9940]

Yes, the Expert Drum spinning on a motor base is continuous agitation. I have a CPP-2, but I've read of many users having success with these drums and a motor base. According to Jobo, if you use a water pre-rinse, developing time doesn't change vs manual agitation in a tank. Personally, I've found I've got to drop development times by 10-15% depending on which film.

[xkaes]

Another point -- that I forgot to add. One type of drum processing is on a Unicolor, Besleler, etc. DRY roller. Some of these reverse the rotation automatically every 30 seconds or so. Others don't -- and maybe some allow you to adjust the rotation speed. I suppose you could use a dimmer switch.
I use drums in a water bath and I can adjust the rotation speed by increasing or decreasing the force of the water on the impeller blades. I set it for about one rotation every second.
These are just other factors that can impact your outcome.

[Willie]

You can also use a tray and a brush for developing. Immerse the film and use the brush up and down, side to side. Then reverse and do it the other direction. Gives the option of doing it the full time in the developer or a short time and then letting it stand for a bit.

One advantage is the lack of scratching on negatives unless you have grit in the solutions.

[Martin Aislabie]

A continuously rotating tank is classified as continuous agitation.

I use a Jobo CPP and Jobo 3010 tanks (shooting 5x4).

I always pre-rinse - usually for a minimum of 5 mins - the minimum time recommended - there isn't really a maximum time.

How long you develop your film for depends on what film + what developer.

If you shoot B&W, you need to be mindful of minimum neat developer requirements - Kodak recommend a minimum of 100 ml of neat D76 per single sheet of 10x8.

I found I needed to dilute D76 to 1 (dev) + 2 (water) to keep my development times sensible (4+ min) when using Delta100.

I did a BTZS film speed/developing time test with Fred Newman at the View Camera Store (very helpful guy) - I would strongly recommend it if you are shooting B&W.

Hope this helps

Martin

[Vaughn]

Another point -- that I forgot to add. One type of drum processing is on a Unicolor, Besleler, etc. DRY roller. Some of these reverse the rotation automatically every 30 seconds or so. Others don't -- and maybe some allow you to adjust the rotation speed.

I opened up my Unicolor motor base and disengauged the switch that reverses the motor -- it was reversing the expert drum before it could do a whole rev. Generally, it rotates fairly slow, so I have not considered modifying the speed.

[xkaes]

My dry tube roller is a Unicolor Uniroller Model 352. I only use it when I'm in a rush -- it takes quite a while to set up my water-bath roller.

The 352 auto-reverses every 30 seconds or so, as I recall. It has no adjustments at all as to speed or direction, but only cost $5 at a thrift store. I didn't know that there are dry rollers that have adjustments. I see some dry rollers on EBAY with prices over $100. Seems ridiculous.

The 352 has a fairly slow rotation speed, I guess -- about one per second -- which I emulate on my wet-bath tubes.

One reason for tube processing is consistency in development, but another is that the film or paper ALWAYS gets fresh chemicals (more consistency) -- and I save money by using a LOT less chemical. It's important to run tests, of course, as mentioned -- but the tests are easy to run and you will be surprised how just a small amount of FRESH chemicals will do the job.

[Vaughn]

I have the Unicolor 352, also. As I said, inside I bent the lever that hits the switch that causes the roller to reverse direction, so that it no longer hits the switch. To reverse direction I just lift the drum and place it the other way round.