Hi everyone,

I use to shoot with an ASI2600MC + Esprit ED80 refractor (400 mm f/5). As I shoot in a bortle 5 sky I use an IDAS LPS D3 to have more contrast on the object, specially nebulae and avoid light pollution. This IDAS is screwed inside the Esprit's field flatterner (non reductor). I mean, the flat fattener has two parts, you unscrew them and inside of one part there's the place to screw the IDAS, then you screw the two parts of the flat flattener and then the IDAS remains inside.

What I obtain are halos in the most brilliant stars. Sometimes are not so big, but others are.

There's no other position to screw the IDAS (I've checked if it was not ok positioned). Anyone else has the same issue?

I link you some example from my pictures in my Astrobin's gallery:

https://www.astrobin.com/ilqjm9/B/  (look at the star on the left side)

https://www.astrobin.com/gry4yk/ (star on the lower left position)

https://www.astrobin.com/cza694/ (in M45 is scandalous)

I'm trying to minimize the halos when processing in PixInsight (with BlurXterminator and others) but I have low success.

Thanks to everyone and clear skies.

Daniel.