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Old 13-01-2014, 09:19 PM
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Originally Posted by Peter Ward View Post
The shift of the center wavelength of a filter can be accurately quantified by a model of the center wavelength λ vs. angle of incidence θ .

With a steep F3 light cone, I suspect you are seeing an intensity transmission effect, which attenuates the light transmission the more you go off axis.

CCDI is probably interpreting these dimmer (hence smaller) stars off axis as some for of field curvature....which it isn't.

I would have thought that this effect would only be justifiable with narrowband filters as with broadband colour the wavelength shift is such a tiny fraction of the light allowed to pass through the filter.

If curvature was measured by brightness then putting a star cluster off axis would manifest itself as curvature. (I don't know if this would happen but I assume it dosn't)
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