>"With 8% loss per air-glass surface on lenses without coating..."https://en.wikipedia.org/wiki/F-number#T-stopWhen calculating T-stop from the f-stop, do I need to do that for each side of a single element or just once per element?
Like 1 element would be: f/2.0 + 8% = T/2.16
Or, will it be each side for 1 element: f/2.0 + 8% + 8% = T/2.3328 (close to the example formula assuming 0.75 transmittance on the wiki above)
I'm thinking it is each side of each element. So, a 2 element lens would be 4 sides for: f/2.0 + 8% + 8% + 8% + 8% = T/2.72097792 I'm thinking this is closer to being correct despite not knowing the exact transmittance. The elements are really old and don't have modern coatings.