Response to Continuous vs Intermittent agitation - finding

> Unfortunately continuous agitation interferes with the formation of sharpness-enhancing edge effects”. Everything I’ve read except Henry’s "Controls in Black and White Photography” seems to agree to this.

To me the big difference is that Dr. Henry documented his experiments in such a way that potentially anyone could perform the same experiment and confirm or refute his conclusions, while Anchell & Troop simply published assertions that may or may not have been backed up by experimental results. The problem with Anchell & Troop is that they usually didn't say so.

For example, Anchell & Troop state that "Because continuous agitation exagerrates highlight development at the expense of shadow development it also results in lower speed and a shorter tonal scale."

My experiment with HP5+ proves that statement dead false; the EI is the same and the curves are identical through 14 stops. I'd have to say that results are the same for each method.

Otoh, the experiment with Delta 100 partially supports Anchell & Troop's statment; it did lose a little speed _but_ the curve shape is also the same through 14 stops.

The curve shape for both films is pretty much straight through 14 stops; I can't imagine what they mean by "shorter tonal scale."

So you see what I'm getting at? Dr. Henry provided experimental results to support his conclusions; Anchell & Troop may or may not have documentation to support their statement about agitation and edge effects. We don't know because no citation was given; for all we know they may have just been repeating common wisdom that a test wouldn't support.

> Isn’t agitation or more correctly minimal agitation in dilute developers what Rodinal @ 1+100 or (T)FX2 and stand development is all about. I keep rereading the original post (good testing, John) and thinking “what am I missing”.

I think you're missing the consideration of acceptable evenness.

Dr. Henry adressed this, almost in passing, when he considered the McQuilkin method of agitation, a very minimal agitation method. He found that the McQuilkin method gave somewhat higher acutance figures than other methods but wrote, "the uniformity of development is the most non-uniform I have ever seen and, therefore, totally unsuitable for photography."

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