I've been doing my film speed test as prescribed in John Blakemore's B&W Workshop book.
I use Delta 400 in ID-11 (1+1).
My testing has led me to believe that I need to rate the film at 200 and extend the recommended development times by 15-20%.
So - as I use a medium format camera hand held most of the time I need a film speed of at least 400 for these grey Manchester days if not 800 sometimes.
How do I translate my new personal film speed of 200 and development time to 400 which, as my simple mind understands it, will be pushing the film. Is this correct?
Apologies if this is confusing but at the moment I am - confused!
Thanks.
- Tony