BW Processing: Rotary Vs. Non - The Final Showdown

[sully75]

Seriously folks...

I'm planning on running my own tests some time soon, but I'm interested in anyone's personal tests of rotary vs. non rotary development. I believe I've heard that rotary development overdevelops the highlights and may promote uneven development. I've tried taco style and rotary development with a Bessler drum on a unicolor base, a couple of times with a duplicate negative, and I can't say that my results have been that different.

That said, I still don't know what I'm doing, so it's hard for me to say. I'd rather not invest too much time going down the wrong road though. I like taco style because it gives me a little additional control if I want to + or - a development time, and I've been able to experiment with stand development. But the Bessler drum is great because you can sort of set it and forget it, it's very convenient. It also is great for quantities. So...I will probably continue to do both.

Has anyone run their own tests and what were your results in comparison? It seems like many people here are using rotary development, but I'm interested in all opinions, rants, tyrades, etc.

Thanks!
Paul

[Brian C. Miller]

The first real question would be, is the film being processed in a device that was meant for rotary film processing?

A lot of the rotary film processing that I've read about on this forum has been done with equipment that was never intended for it. If the equipment wasn't designed for processing sheet film, then why should someone be disappointed when the results aren't stellar?

I have a Jobo 4x5 Expert drum, the 2509N, and of course tray development. I've also tried a Yankee tank, and I'm not going to use that ever again.

I have used the 2509N with my CPE2, and I had some issues with (mainly) loading. I don't remember doing a test specifically for uneven development like I did with my Yankee tank. The Jobo Expert drum has been flawless. Tray development (with my slosher) has been flawless.

[sanking]

Seriously folks...

I'm planning on running my own tests some time soon, but I'm interested in anyone's personal tests of rotary vs. non rotary development. I believe I've heard that rotary development overdevelops the highlights and may promote uneven development. I've tried taco style and rotary development with a Bessler drum on a unicolor base, a couple of times with a duplicate negative, and I can't say that my results have been that different.

That said, I still don't know what I'm doing, so it's hard for me to say. I'd rather not invest too much time going down the wrong road though. I like taco style because it gives me a little additional control if I want to + or - a development time, and I've been able to experiment with stand development. But the Bessler drum is great because you can sort of set it and forget it, it's very convenient. It also is great for quantities. So...I will probably continue to do both.

Has anyone run their own tests and what were your results in comparison? It seems like many people here are using rotary development, but I'm interested in all opinions, rants, tyrades, etc.

Thanks!
Paul

Rotary development , if done correctly with the right equipment, can not be beat for even and smooth development of film. The very best method of rotary, IMO, is in BTZS tubes where the tubes are rotated in a tray of water. This is the method introduced and used by Phil Davis because it was the only method that provided the kind of even development and consistency needed for his BTZS workshops. One of the reasons this method works so well is that agitation is almost totally random and varies a lot as the tubes bob up and down on each side as they rotate on the other axis.

Rotary development that is totally mechanized, especially with very fast rotation, may produce development artifacts like bromide streaking. Bob Carnie of Elevator Digital mentioned recently that in order to avoid streaks he always agitates manually for the first minute or so of development. That would also work well when developing film in print drums on motor bases.

If even development is one of the major pros of rotary development, reduced film speed and reduced accutance are the cons. Film will give more effective film speed when it is developed in dilute solutions for a long time with reduced agitation. This type of development also usually produces more acutance (= greater sharpness).

And yes, I have tested all of this, many times over. Based on my experience and testing I always use rotary development for film testing when even development and consistency is most important, and minimal agitation or two bath development when maximum shadow detail and sharpness is wanted.


Sandy King

[Jay DeFehr]

I agree with everything Sandy says above. Randomness is the key to even development. The taco method, despite its humble nature, provides for very random development because the film itself produces turbulunce that prevents any kind of patterned development. I prefer the taco method to BTZS type tubes, because the taco method is a true daylight process. Developing for maximum acutance is mostly a curiosity for me, and as a result, I have many images that are too sharp for my taste. Rotary development takes some of the edge off, but not much. An acutance developer will not produce soft-edged images, even with rotary development, but it helps a little.

[Lachlan 717]

Is there any value/use in changing the rotational speeds during the development to avoid any artefacts (mimicking, I guess, the random movements mentioned above)?

[Kevin Crisp]

I just develop in trays, two sheets at a time. I glued a little plastic piece in the bottom of the tray that keeps the sheets from ever hitting each other. (Two legs of the tripod thing that comes with delivered pizza.)

For agitation I follow the lift the edge of the tray method Kodak recommended for TMAX development in publication F- something. This is basically a fairly mild form of constant agitation, repeated as a three part motion every 8 seconds. Since the sheets of film have room to move around in their halves of the tray it is quite random. It is plenty repeatable for me and fairly mindless activity I can easily do while thinking about other things in the dark. Even with So. Cal. development times down into the less than 5 minute range I have no problems with evenness.

I am not knocking rotary development, I've just been completely satisfied with trays. I have no need for a 'daylight process.'

[sully75]

Possibly silly question: I wonder if there is something to put in the circuit of a unicolor base to randomize it a bit more. I have the reversing base, and the speed it rotates at doesn't seem excessive, but I wonder if slowing the speed some and/or introducing some vibration might help.

[sully75]

or, what Lachlan said.

[sully75]

If even development is one of the major pros of rotary development, reduced film speed and reduced accutance are the cons. Film will give more effective film speed when it is developed in dilute solutions for a long time with reduced agitation. This type of development also usually produces more acutance (= greater sharpness).

And yes, I have tested all of this, many times over. Based on my experience and testing I always use rotary development for film testing when even development and consistency is most important, and minimal agitation or two bath development when maximum shadow detail and sharpness is wanted.


Sandy King

Hi Sandy,

For the record, what developers are you using, particularly for your two bath and minimul agitation development? Could you give examples of the types of scenes that might recomend one over the other? I'm thinking you would go for even development in a scene with a lot of sky, and your two bath in a high contrast scene with a lot of shadow detail, but could you elaborate on that decision?

thanks
Paul

[sully75]

I agree with everything Sandy says above. Randomness is the key to even development. The taco method, despite its humble nature, provides for very random development because the film itself produces turbulunce that prevents any kind of patterned development. I prefer the taco method to BTZS type tubes, because the taco method is a true daylight process. Developing for maximum acutance is mostly a curiosity for me, and as a result, I have many images that are too sharp for my taste. Rotary development takes some of the edge off, but not much. An acutance developer will not produce soft-edged images, even with rotary development, but it helps a little.

Hi Jay,

Just wondering, are you doing 5x7 taco style by any chance? I'm currently doing 2 negs in a stainless tank but I was wondering if anyone is doing 4 negs, 4x5 style, in any kind of tank.

Thanks
Paul