I need some help whit ND filters.
I wonder if you can give me some advise.
I want to use a 4x5 film rated ISO 100 and I wont to reduce the ISO factor under 1 ISO (minimum 1 ISO).
I want to shot 90 minutes (aprox.) minimum 1 hour. Off course will depend also of the light available (exteriors).
I know some people have use a 16x ND filter to get such long exposition.
I was looking for ND filters and I find the B+W ND filter series, they are the only one I find whit high factor.
Bud I get a little confuse whit the filter factor and the f-stop reduction.
which filter I should use? a B+W 106, 110, 113, 120?
This is the link of B+W
I will really appreciate if you have some experience to share.
By the way, which holder system you recommend, certainly I will use other filters like Graduated ND, Polariser, B&W and temperature correction.
I shoot 4x5 and my first lens is a Rodenstock Sironar-N 210/5.6 MC if someone know what is the filter size for this lens I would really appreciate.
Thank you very much Salvador