+1 to Michaels advice.
I would say to use box ISO speed and developers recommended times and dilutions. Then....
- If results are consistently OK then change nothing.
- If results are consistently too contrasty and/or thin half ISO speed and reduce development by 30%
- If results are consistently too soft (lacking contrast) and/or dense double ISO and increase development by 40%
Fact is the results will be dependant on metering technique (in camera, hadheld incident or handheld spot) and the typical
Subject
Brightness
Range.
Where the
SBR is normal, which is around 7 1/2 stops from black to white, then box iSO speed and 1. above should be your standard.
Where the
SBR is consistently greater than normal 2. above should be your standard.
Where the
SBR is consistently lower than normal then 3. above should be your standard.
To guarantee getting something printable 99% of the time then use a handheld incident meter and 2. above.
When using a handheld incident meter optimally, place it at highlight on the subject and point it directly at the primary light source (Sun, Sky, Window, Flash). This may not give you the best contrast in your negatives but it will make them realatively easy to print.
The problem is, as always with roll film, you may have some subjects on the roll which have normal SBR, some with high SBR and some with Low SBR and trying to get one EI which fits all optimally simply can't be done. Option 2 above is the best compromise unless you know in advance that ALL images on the roll will fit into only one of the three posssibilties in which case you use that specific option.
Then adjust to taste as experience is gained.