I can definitely see where measuring contrast could be problematic.

Quote Originally Posted by Ian Grant View Post
I'm not familiar with a PML2 but you may need to read more than one colour channel, and its not staright forward.

One reason this is a murkey area is the stain can act a a contrast filter, or even like a very mild safelight filter.

When a negative is intensified in a Uranium intensifier it goes redder and is visually less dense but prints with significantly more contrast and as far as a blue sensitive papers concerned needs more exposure.

Some staining developers give a yellowish stain others redish and this can vary depending on the film as well.

I use staining developers for prints occasionally and once the stain is formed the choice of stop bath and fixer has no effect on the stain.

The staining is the same after an alkali fixer or conventional Rapid fixer (unhardened) and is not affected by HCA (sodium sulphite) either.

Ian