Not a theory--it's what happens. put a piece of unexposed film in developer and let er go for 5, 10, 15, 20 minutes....like about 10 mintues is where the fog starts developing--the background fog. developing this with the rest of the image pushes all the tones up up up and compresses them and therefore reduces contrast and dynamic range. at the same time, you're developing stuff that should be getting saved to make the reversal image-the more stuff developed in the first developer, the less that's left to make image dmax in the second development.
Originally Posted by Tofek
I like dmax. That's another reason I don't like hypo in the first developer--i want the densest image I can get--I can always subtract from that with bleach if I want. if you take away stuff before you even see it--well, that seems foolish. I believe using a post bleach method, it's possible to get a higher effective film speed than any first developer-hypo method--AND by inspection!
Since post bleaching is an added step I gave up on it like I gave up on the monobath first developer.
My preferred method is to give adequate exposure to use a non-hypo first developer--this can't help but give the max dmax and maximum dynamic range--no way to argue that it don't.
Ok that's clear, thank you :) . I was thinking : since we have a too dark image the dmax should be lowered, but you mean that the image 'quality' will suffer from that. Like there won't be 100% dark darks, right?
Now let's see if the projector is capable of seeing through that high density...
I don't think the minuscule quantities of hypo affect in any way the Dmax.
I read somewhere (G. Haist) that hypo in the first developer serves as "developing nucleation center" (sorry for my being non technical) that is it mainly helps grains to be developable.