Star Shape

[tony_cameraguru]

My equipment consists of: Explorer Scientific 80ED 480mm - Canon 250D astro modded - Field Flattener - UHC filter. The sub shows a close-up of a star, and the reddish hue on the right side that seems to be a common effect on my imagery. This particular star is near the centre of the sub. Can anyone assist me in analysing what may be wrong please?

 

Thank you. Tony

[alacant]

Hi

Using live view at 10x -preferably on a large screen- get close focus using a Bahtinov mask. Now remove the mask and focus a tiny amount away from that position until the red halo just disappears.

HTH

Edited August 22, 2021 by alacant

[tony_cameraguru]

Thank you I will try that.