Attached Link: http://www.mrpinhole.com/exposure.php

Go to the site I linked to, and have a conversion chart generated for your f-stop.

Then you will need to make a new chart for each film you use, that factor in that individual film’s reciprocity failure.

If you are going to use B&W film, use Ifords HP5 as it needs very little adjustment for reciprocity failure, whereas TriX needs a lot (a 15min exposure turns into 1 hour).

 

I use to do a lot of pinhole photography with a bunch of homebuilt cameras (120, 4x5 and 8x10).

Here is the only one I kept after going digital ….my Pin-o-Flex (hey don’t laugh, it has a viewfinder).

Chuck