Weird distortion with Sigma 24mm and clip-in filter

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mermaidkiller Senior Member • Posts: 1,094
Weird distortion with Sigma 24mm and clip-in filter

The Sigma 24mm f/1.4 is an excellent and bright standard lens for astrophotography. Even squeezed to f/2.5 it is bright with better corner sharpness.

BUT: When using a clip-in, all edge sharpness is gone and replace by radial stripes, really ugly.

With my wide angle, the Samyang 14 f/2.8, the same issue appears ?

With other (telephoto-) lenses, such as the 50mm f/2.5 or 100-400Lii or my ED110 (f=600mm) telescope, this does not appear, the picture appears normally like without filter, except the unwanted light pollution filtered out.

Do these filters work on telephoto lenses only and are not for standard or wide angle ?

Look at the ugly corners .... (the lighter edges around the foreground has nothing to do with the lens or filter)

Here an original single frame downsampled to jpg.

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