chuckroast
Subscriber
Isn't the OP asking about differences between 510 Pyro and Pyrocat HD so what's the relevance of PMK, other than it is another staining developer that is different from the two the OP want to know about ?
pentaxuser
Because 510 stains and prints more like PMK than does HD. It's just a point of reference from those of us who have used all three.
One of thing that commends 510 (and why I have "fixins'" here for it) is that it handles big SBRs much like PMK - that is to say, it manages highlights very well - but works much better than PMK with 35mm wherein grain can become an issue.
As noted upthread, HD[C] doesn't shoulder off highlights anywhere near as much so big SBRs have to managed more carefully.
