So the details: I have 7219, rating at asa 320.
I'm lighting to the meter @ asa 320 for a key stop of f8.
I'm shooting through some wonky lenses that loose at least 2/3 a stop (let's say 1 to be safe). That means light hitting the film is around f5.6.
But the film is actually 500t that I'm overexposing, so what's hitting the film is actually 500t @ f4.5? Or so?
I can't find anymore 500t (thanks walking dead), but people have loads of 200T - If I light for 200t @ f8, then loose a stop the math then works out as follows:
asa 320 = f8 on the meter (loose a stop due to lens = f5.6) asa 500 would = f4.5 as we gain the loss from the lens back plus the stock sensitivity. Really, were only talking 2/3's over exposure here.
asa 200 would = 2/3's underexposed meaning I would then need to shoot at f...3.2? to gain the loss back?
I want to intentionally over expose the 500t by 2/3 stop. I want to match this footage with the 200t, but I don't want to relight the scene!
I don't really need to over expose the 200t if I can get away with opening up the lens from f5.6 to f4 or so.
Thoughts? Math is hard.