Rotary Processors inadequate for LF Sheet Film. True?

[zarrir_junior]

<p>Stephen Anchell, in the Film Developing Cookbook, discorages the use of Rotary Processors (like Jobo CPA, CPP) for sheet film processing. According to him, continuous agitation supresses the adjacency effects that enhance film sharpness and exaggerates highlight development at the expense of shadow development, resulting in a shorter tonal scale. I´d like to know what you guys can say about this. Aren´t there specific speeds of rotary action for sheet film processing that would inhibit this side effect? Is this loss of sharpness really noticeable? According to the author, this adjacency effect is caused during the still periods of development.</p>

[fourthst]

<p>Some people swear by Rodinal, some D-76. It's personal opinion. I've used rotary processors for a long time with roll and sheet film, commercially and personally. I think they work fine but then my prints probably aren't as beautiful as Mr. Anchell's. Rotary processors almost certainly suppress the adjacency effect and certainly effect contrasts. This makes a different negative, not necessarily a bad negative. So, I don't know that this should disqualify rotary units from processing sheet film. Do keep in mind the amount of developer required to the sq. in. of film being processed. The drums can get heavy and have an adverse effect on motors. A full load of 8x10 in an expert drum on the CPA/CPP can be a real push. Also, I've not had much luck with them and pyro developers. I get what looks like bromide drag certainly due to the rotational agitation.</p>

[AJG]

<p>It took some testing to arrive at a custom dilution of HC 110 and the exact time, but after doing that I have had extremely good results with a Jobo 2 reel 4x5 tank on a Unicolor agitator. I haven't seen any of Mr. Anchell's prints in person, so I don't know if I am missing something, but I have processed upwards of 5000 sheets of Tri-X, and more recently, HP 5, and so far I haven't had any noticeable loss of sharpness or tonal range with 16 x 20 prints.</p>

[bruce_watson1]

<p>Commonly believed urban myth. There is no scientific evidence that this is true. Not a single peer reviewed paper in a journal anywhere that I could find. Grant Haist, the revered Kodak researcher, in his two volume tome <em>Modern Photographic Processing,</em> found no evidence that agitation has any effect on accutance. Neither did Henry in his book <em>Controls in Modern Black-and-White Photography.</em> At least if it's there I didn't find it.<em> </em> If someone can cite a paper that reveals the truth one way or the other I'd love to see it, so please post a URL, or a paper citation.</p>

<p>I went through this very same problem (how to process sheet film) myself six or seven years ago. Did a ton of research over at the local university library. What I found was exactly this -- people say, people believe, people even hope, but people haven't published any actual science. And without scientific evidence, we just don't know.</p>

<p>For what it's worth, John Sexton uses and recommends Jobo processing of sheet film with the expert tanks. I doubt pros like Sexton would be doing it, and teaching it, if they thought it was inadaquate.</p>

<p>The thing is, there's a lot more to LF photography than accutance. If accutance is your game, you can do better with a Mamiya 7 II and some good glass, and better still with 35mm. With LF, especially at the capture apertures we use to control DOF, we are largely diffraction limited. IOW, a given square cm of 35mm film can be (a lot) sharper than a given square cm of 5x4 film. But... to make the same size print, the enlargement of the 35mm film has to be much greater. And when you enlarge, you enlarge everything, from image detail to grain to dust on the film.</p>

<p>For my LF work I value even and consistent development over raw accutance. For me it's more about tonality than sharpness. But I find with rotary processing I get both. I get excellent tones and tonal transitions, and excellent sharpness too. Enough so that I get excellent sharp smooth prints even at 125 x 100 cm from 5x4 negatives. Which is just about big enough for me ;-)</p>

[keith_tapscott]

<p>Bruce has made some valid points. I believe that acutance (only one `C`) is a grossly overstated phenomenon and a good way for the marketing people to sell their `<strong><em>magic potions</em></strong>`.</p>

[fourthst]

<p>I was trying to be tongue in cheek when I referred to Mr. Anchell's prints. I've never seen one either, but I don't doubt his technical ability. Just to be clear, I was referring to the adjacency 'effect' or 'Mackie Line' mentioned, not a films inherent acutance. One shouldn't underestimate the adjacency effect on the final appearance of a print. The effect is well known and can indeed be achieved with stand, semi-stand development or the use of partially exhausted developers. There are also developers designed to bring out such qualities. I am now venturing into an area I know little, if anything, about: I'm lead to believe modern emulsions do not react as readily as did the older emulsions to these techniques. Alas there is no magic or alchemy involved. This is where you need to experiment and see what works best for you.<br>

All that said, modern emulsions and developers are capable of producing superb negatives, yes, even in rotary processors. Need proof? As Bruce points out, look at some of John Sextons work.</p>

[jay_de_fehr]

<p>If you want to encourage adjacency effects, rotary processing is not the best way to do so. Contrary to what Bruce says above, adjacency effects, the mechanisms that produce them, and the role of agitation is well understood and well documented. See Developing, Jacobson and Jacobson. Haist and Henry weren't interested in encouraging adjacency effects so much as avoiding them, and the developers they referenced were general purpose, MQ developers much like D-76. Anchell, on the other hand, seems to assume all LF photographers are most interested, not just in acutance, but exaggerated acutance, which seems unlikely to me. I use a Jobo ATL automated rotary processor for the vast majority of my development, but there are times I want to exploit the compensating effect of stand development, or the unique properties of an acutance developer, and in these cases the Jobo is inappropriate. Photography is a medium of compromises, and film development is full of them, so there is no "one-size-fits-all" development process. Some are happy to use one method, others prefer a different one, or a combination of approaches, and all have their merits, but Anchell's specific claim that rotary processing "exaggerates highlight development at the expense of shadow development, resulting in a shorter tonal scale", is misleading, at best. "Exaggerated" and "shorter" as compared to what? If Anchell doesn't understand that it's possible to develop to any chosen Contrast Index, or negative Density Range with rotary processing, I question his authority. </p>

[scott_davis5]

<p>I've been using Jobo Expert drums for everything from 4x5 to 11x14. I use Pyrocat HD as a developer, which was developed for use in rotary processors (certain older formulas like PMK Pyro and ABC Pyro don't do well in rotary processors because of rapid oxidation of the developer). I use my negs for platinum/palladium printing, and have been extremely happy with the results. So, the myth that large format is incompatible with rotary processing is just that, a myth. I like rotary processing because it reduces/eliminates problems in handling film, such as scratches or fingerprints. I know many people are quite happy with tray processing, but I'm not terribly successful with it, and I'm not a big fan of standing around in the dark for half an hour with my hands immersed (albeit in latex gloves) in chemistry. For all of the previous reasons, rotary processing works fine for me.</p>

[profhlynnjones]

<p>Regarding my friend Keith, Amen, Brother.</p>

<p>Rotary processing of still photography is the very best that can be achieved in terms of sharpness and manufacturer anticipated effectiveness. The second best is highly competent tray processing. Any less agitation will have an affect which may be more desirable or less desirable, depending upon your needs and desires, see below. .</p>

<p>"Edge Effect" is a special quality of image in which light colored line are ajacent to less light colored lines, and darker lines are ajacent to dark lines. The effect in a print at normal viewing distances is very impressive, creating a near bas relieve effect. However, this effect is obviously and provably significanty less sharp than a normally processed effect. I personally love it for certain kinds ov b/w prints. You often get it by accident with chrome films, look at any detail next to a deep blue sky.</p>

<p>How do you get "Edge Effect", expose fully using a thicker film such as TX or HP5, use D76 or D76 1:1, after the initial agitation of 15 or so seconds, agitate only once each 2 or 3 minutes, however don't eliminate agitation or you may get some very negative results such as the negative version of ajacency or bromide drag. Agaceny Effect is always classified as a "processing defect" in t eliterature, commonly associated with thick emulsions, over exposure, and lack of agitation. The desirable version of ajacency is commonly called "Edge Effect" and is a controlled variation of the process. </p>

<p>Lynn</p>

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