Gene N replied to the topic 'Strange artefacts on my images' in the forum. 3 months ago

Hi Ralf,

A real back of the envelope calculation
astronomy.tools/calculators/dust_reflection_calculator

Plugging in 72mm, 420mmFL, 0.85FR, 2.4umPIX and 687 pixels donut size I get approx 8mm.
Best guess is the sealing glass cover on the front of the CCD camera itself

Gene

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