developing at higher dilutions

[Robin H.]

I'm about to develop a roll of FP4+ (E.I 100) in APH09 diluted 1+100 but I'm not sure about an exact developing time. I'd like to try semi-stand because there were a few contrasty scenes. Can someone help me out here?

 

[df cardwell]

Without testing it out, there isn't any way to determine an 'exact' time.

First of all, FP4 in Rodinal with NORMAL development will hold over 13 f/stops in a straight line !
The only problem is getting all that to fit onto normal photo paper.

Reducing the agitation does reduce the contrast of the highlights, to allow them to fall to printable densities.
The trick is to increase the development time to restore the density in the shadows, and the contrast to the midtones.

That is easy. A rule of thumb is to add fifty percent to your normal development time, and reduce the agitation to 15 seconds every 5th minute. This assumes your normal agitation is once per minute. If you agitate every thirty seconds, double the development time and agitate every fifth minute.

This ALSO assumes that you are using 1+50 dilution. 1+25 is too concentrated for the highlights to drop noticeably.

The reason I'm not suggesting 1+100 is that it makes no real difference other than increasing the development time.
It also increases the chance of development errors.

If you have another roll of FP4 on hand, why not test this before you throw something important into the tank.

It's like making soup; we ALWAYS taste it before we serve it !