I find David Kachel's SLIMT technique useful for handling long subject luminance ranges. For those not familiar, it is a means of using highly dilute potassium ferricyanide between exposure and development to hold back density in the most exposed parts of a negative or print. (Details are provided on his website; just search for his name, and then for SLIMT on his home page's search function.) One thing I noticed when retesting/"calibrating" it a couple of years ago, was that in smaller formats (35, 645), the grain in the high values became a bit less distinct and resulting enlargements slightly less sharp with SLIMT processing than without. I should mention, I use D-23 developer. I was comparing N- contractions between D-23 1:1 with SLIMT and D-23 at 1:3 without. SLIMT processing does a superior job of holding shadow detail, while the 1:3 dilution yields an exquisite highlight detail.

I asked Mr. Kachel about it, but he had not noticed this effect, probably because his work is large format. I am just curious as to whether someone here might know why either potassium ferricyanide or potassium bromide, or their combination, even in the extreme dilutions used in SLIMT (around 1:1000) might cause this. For my work -- mostly portraiture -- the issue is not crucial. I'm just curious.