Extended film development

Increasing film speed when developing in your own lab is easy: With negative color film, you get the gain by extending the color development. With slide material, you gain one more aperture by extending the first development.

It’s a little different with black-and-white film. For them, type-specific chemistry in the strict sense does not exist: large laboratories work with a standard tank developer into which they simply hook films of all manufacturers and all sensitivity classes. The film manufacturers have had to adapt to this and adjust their emulsions so that they can tolerate this treatment. The films may not give their best, but the negatives can still be copied.

You can only achieve really good results with black and white in your own lab. And it quickly becomes apparent that certain films get along particularly well with certain developers and that certain film properties can be used preferentially if you only use the corresponding developer. In such cases, we speak of ideal film+developer combinations.