MirkoBoeddecker
Hello Robert,
The vignetting behaviour of the Pan 25 and the CHS 25 is so good that you don’t need any extension factors up to 1/2 second. Beyond that, the two differ slightly.
We haven’t tested this in detail yet, though. What time ranges are you working with?
You can use the CHS 25 as a guide, though. Fuji and Foma don’t have 25 ASA films, so they’re not a good comparison.
Best regards,
Mirko