[Stonius (Markus)]

Hi there,


I was reading how binoviewers require higher spec (?flatter?) diagonals because of the longer light path.


So I take it that a distorted wavefront gets worse with distance from the point of distortion? Is that right? Otherwise binoviewers wouldn't need higher spec diagonals.



If that's true, filters, which are typically found just before the sensor anyway, would similarly have to be higher spec the further they are from the sensor, same as with the diagonal.



If that is true, then those astrocrumb filters that sit just inside the OTA might not be the best spot for filter placement, eh? Maybe it doesn't make a difference for visual.



But then I'm thinking that as *all our optical surfaces are imperfect to *some degree, wouldn't that mean the imperfections in *any optical surface get worse with distance?


But if that's true then a long focal length instrument would suffer more from a 1/8 wave imperfection than a short one, and I don't think that's right.


...is it?


Can some kind soul tell me where my thinking has gone astray?





Markus