Agitation for 4x5 w/Rodinal

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I understand that the lovely edge effects created by Rodinal are due to a compensating activity where the highly exposed areas of the film tend to exhaust the developer. Normally when tray processing 4x5 sheet film I constantly shuffle the films in the tray. Does this mean that I'm losing out on the edge effect since the developer does not have time to become exhausted? Should I let the film "rest" for a while to increase edge effect? I assume my processing time will need to increase if I do this--correct?

BTW my film is Ilford FP4plus rated at 80 and I use a 1:50 dilution for 10 minutes.

Thanks

-- Phil Redman (pjredman@usgs.gov), June 26, 2001

Answers

Dr. Richard Henry, in "Controls in Black and White Photography," states that his tests show adjacency effects are caused by "lateral diffusion in the emulsion layer" and are not dependent on agitation. There are plenty of other people who swear that reducing agitation increases edge effects, but none that I know of who have conducted verifiable tests like Dr. Henry.

You may wish to try greater dilutions to increase edge effects--such as 1:75 or 1:100--but you will probably lose film speed.

-- Ed Buffaloe (edb@unblinkingeye.com), June 26, 2001.


Phil, Reducing agitation does several beneficial things. One, it improves resolution of fine detail, it improves sharpness by enhancing adjacency effects, it lessens grain clumping and it significantly smooths tonal gradation. I would suggest agitating constantly for one minute, then 10 sec./min. thereafter. You will need to increase your development time by about 30%.

If you want to experiment further with this concept, try diluting your developer to 1:100, and double the adjusted time, which in your case would be 26 min. Use the same agitation method. You probably could get by with agitating 10sec/3min after the midway point with little difference. This, admittedly, is tedious, but the results will amaze you.

-- Ted Kaufman (writercrmp@aol.como), June 26, 2001.


Ted, others, I have read in the "cookbook" about the above-mentioned benefits of this developing scheme, however they state it should only be used with very highly dilute, non-solvent developers. Of course rodinal @1:50+ qualifies as such, but is this "gospel according to Anchell/Troop" correct concerning other developers? I am thinking of D76 1:3 for Delta 100. Any insight? Thanx-

-- david o'connor (dco@definitive-security.com), June 30, 2001.

I've run quite a bit of Delta 100 (and HP5+) in D-76 1:3 both using manual intermittent agitation and in the Jobo.

First of all, given enough manual agitation for good evenness, compared to continuous agitation curve shapes are _identical_. That is, there is _no_ compensating effect resulting from intermittent agitation.

Second, if there are any edge effects that result from intermittent agitation in D-76 1:3 compared to rotary agitation, I can't see them in 11x prints from 35mm or with a 30x magnifier.

I think modern films have made obtaining significant edge/adjacency effects and compensating development pretty much unworkable, and for the most part today such things are the result of "wishful seeing," which of course I've engaged in too. We're not using Super XX any more.

-- John Hicks (jbh@magicnet.net), June 30, 2001.


Thank you, John - You answered my question. By "modern films" are you referring to Tgrains/coreshell? In which case, a conventional film such as fp4+ may actually benefit from the above-described methods? Or, do most films available in these "modern" times lack the ability to be manipulated as easily as past emulsions. Thanx again.

-- david o'connor (dco@definitive-security.com), June 30, 2001.


> "modern films" are you referring to Tgrains/coreshell?

Not necessarily; I've found HP5+ to behave very much like a T-grain type film, needing what amounts to practically "heroic measures" to get any really significant changes in curve shape. I'd expect FP4+ to be about the same.

I think the only "old" film available is the new Bergger BPF 200.

-- John Hicks (jbh@magicnet.net), July 01, 2001.


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