On 2/21/2022 5:23 AM, Wayne Shumaker wrote:
At 2/20/2022 05:13 PM, Moose and Mike wrote:
<<<OK, this raises a question. Why does linear distortion matter - for this
specific purpose? If the stars are nice pinpoints, does it matter if their locations
differ a bit from a true star map?
Agreed, but any tutorial I have read said to not correct distortion. Also
might screw up the stacking with dark frames. Do you think the stars would not
be affected? You know more about how the various correction algorithms work
than almost anyone.
Any distortion correction involves some interpolation. The question is whether
the interpolation has enough effect to further smear the distortion.
In the specific context, stars, I think it's more a matter of relocation than
smear.
Probably some but also probably not significant relative to the number of
pixels making up the blur.
I tend to agree, and disagree.
My first use of distortion correction, with a film landscape, was impressive; the main subject was nicely corrected. It
also distorted something in the far corner. Pre correction, it was obviously an aluminum can. Post correction, it was
changed in shape enough to not be recognizable. (Cloned out, either way.)
OTOH, I just looked at a shot with a license plate near the corner in DxO PhotoLab, where one may turn correction on and
off. The bits of detail, such as text, seemed equally clear either way.
Who Knows Moose
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