I was wondering how to calculate the ASA/ISO/EI on a light meter when using certain filters.
For example my stock is 250 ASA, and I'm using an ND9 + a polarizer, this means that I lose 3 stops + 2/3 of a stop.
What would my ASA then be set to?
I'm not sure how to work this out.
I understand that I can just take it away from the F stop reading, however, I'd like to be able to just set the ASA on the light meter and then not have to worry about that maths, and just adjust whenever I swap out any filters, rather than doing the maths every time I take a reading.