An added tidbit: I've used DD-X for HP5+, at a 1:9 dilution. Grain, acutance, curve shape and speed were pretty much identical to Microphen 1:1. Or to cut to the chase, grainier than D-76 1:1, higher acutance and 2/3 stop faster.(posted 8757 days ago)DD-X is fairly expensive, but a little goes a long way. My bottle is dated 9/27/99, I got it sometime in November 1999, and there's about 200ml left of the liter. I've been storing it in the refrigerator and as of last week it was still good.
Assuming DD-X is essentially Microphen with a longer-lived version of phenidone, I'll also assume that the 1:4 recommended dilution is the same as stock Microphen.
If so, it contains about 100g/L sodium sulfite, which Crawley contends is far too much for modern films. In a way, many of us apparently concur because we commonly dilute high-sulfite developers, bringing the sulfite level down to 25g/L-50g/L.
In fiddling with Delta 100, I've found that developers with no or very little sodium sulfite carry a speed loss of a stop or so, while adding as little as 10g/L sodium sulfite brings the speed back up without altering curve shape.
A tidbit: adding 12g/L sodium sulfite to Rodinal 1:100 for TMX removes the shoulder at the high end; in fact, it makes the curve sweep _upward_. Usually we don't want that, but it may come in useful sometime.
Anyway...I'm thinking that probably the sweet spot for Delta 100 in DD-X will probably at 1:9 or higher dilution; I'd expect that to give the best balance of fine grain and high acutance _for that combination_.
I'm onto something else, so it'll be up to one of you guys to test Delta 100 in DD-X. I've been rather happy with Delta 100 in D-76H 1:1 or 1:3, but I just got a couple of bottles of FX-39 to try.