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I think I have miss explained what I was asking. I am after the other way around though I am not sure even that applies as FSD seems to grow with AFOV too.
What I mean is, if you had the same TFOV between two eyepieces (So same field stop) but different apparent fields (Say an 82 degree EP compared to a 68) do you get a darker background?
I suspect that it is probably a moot point as deeper digging seems to indicate that the smaller AFOV eyepieces have correspondingly smaller field stops and thus TFOV than equivalent FL wide AFOV ones.
The ones I am comparing directly don't quite make sense to me. The ES 30mm 82 degree has a larger field stop than the Nagler 31 and so should have a larger TFOV. How can you take a large TFOV and spread it over the same apparent field while having slightly higher mag? The field stop is directly measurable and hard to fake so I suspect that the AFOV of one or both is not actually 82 degrees, one is larger or one is smaller or both.
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