adjacency effect with drum processinggreenspun.com : LUSENET : Large format photography : One Thread
I tray process my film and find it to be a tedious chore, and as one famous photographer said "Photography is 20% inspiration and 80% drugery". I am quite satisfied with the quality of my negatives and was wondering with all the posts about the easier method with drum processing, don't you lose the adjacency effect with constant agitation? According to the Master photographer "Ansel Adams" he discovered that the rest intervals between agitations actually allow for something called the "adjacency effect" that causes negatives to be sharper. It's somewhat subtle effect caused by the microscopic exchange of the oxidents across the boundaries between highlight and shadow areas. This causes the edges to be slightly denser on the highlight side and slightly less dense on the shadow side, giving the appearence or greater separation between the two. Constant agitation eliminates this effect so he recommends against it. I need to know if this theory is still true today with todays modern films and developers or is it outdated or disproved information? I know that they're famous photographers that use drum processing exclusively and are world renowned for their work and I can't stop wondering how much better their work would have been if they did the 80% drugery?
-- Belden L. Fodran (Caltari@aol.com), April 25, 2000
Most photography requires a choice to be made, depending on the end effect desired. For even development (and therefore a smooth tonal scale), and high resolution, it is difficult to better the constant agitation provided by revolving drum processors. (I can't afford one, unfortunately).
"Edge effect", or "Mackie lines", or "Eberhardt effect" all describe the same thing, whereby reduced agitation of the film during development limits the supply of fresh developer to the film surface, which remains in contact with the oxidised products of development. This results in significantly reduced resolution, but can create the illusion of greater sharpness by producing dark lines around dark objects, and white lines around lighter objects, and may be desired for certain photographs (e.g. portraits).
At the end of the day, it depends what type of image you want to produce, and whether inducing edge effects would be appropriate or not.
-- fw (email@example.com), April 25, 2000.
In short, yes. A variety of edge effects due to bromide migration are possible and are dependent on periods of rest between agitation. Changing the shape of the characteristic curve (for any film- developer combination) also calls for differences in agitation patterns. I'm afraid its something of a personal choice at the end of the day. While trays and intermittent agitation can yield an edge effect, continuous and random agitation seems the best in terms of avoiding irregular development. I've settled on the following pattern. I use continuous rotary agitation for most normal negatives using developer dilution and time as controls for the needed contrast index. But I still have negs that call for other styles of processing which I do in trays. The most common are extreme contractions where I would like to have an artificial and pronounced shoulder. A choice of procedure as far as the edge effect goes depends on subject. If the subject has a profusion of fine detail and reasonable local contrast (without those two criteria, you're not going to get much of an edge effect anyway), I develop in trays with intermittent agitation. If I have any areas of smooth gradation, I would rather ensure even development with continuous and random agitation than have mottled areas of uneven development. DJ
-- N Dhananjay (firstname.lastname@example.org), April 25, 2000.
There is probably a loss of adjacency effects with drum processing, but I am not sure this is all that bad. Adjacency effects create a sharp look by increasing the contrast in small areas of the negative. As you say, the edges have increased contrast. This increased contrast has a negative effect on gradation. A high definition developer like FX 1 is known for its poor gradation. Here is what Anchell says about adjacency effects:
"If sharpness through adjacency effects were always desirable, all developers would be high acutance. It is not. As sharpness increases other image quality criteria--grain and micro-gradation--suffer."
High micro-contrast results in high sharpness due to adjacency effects and blown out highlights, which is the problem some have with T-Max films
I am not into high acutance, as I use a solvent developer (D-23), which is known for its low definition (poor sharpness is small areas). Such a developers also provides smoother gradation, better rendition of highlight detail, and does not emphasize camera shake or subject movement, as a high acutance developer would.
In summary, I would not worry about it. If you want to compensate for the acutance loss in drum processing, use a high acutance developer, FX 1 or FX 2.
-- William Marderness (email@example.com), April 25, 2000.
There's some thought that most edge/adjacency effects actually occur _within_ the emulsion rather than at the surface; therefore constant agitation doesn't reduce those effects as much as has been assumed.
-- John Hicks (firstname.lastname@example.org), April 25, 2000.
Continuous drum agitation will minimize the adjacency effects. See The Film Developing Cookbook by Anchell & Troop.
I use the Jobo tank with intermittent inversion agitation & get fine results without the bother of sheets in trays. I've got arthritis and think I'd quit LF photography if I had to do sheet/tray development. I'd probably ruin more that I'd get done right. The above book offers the same processing as I'm doing, so it's backed by competent authorities.
-- Charlie Strack (email@example.com), April 25, 2000.