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Strange "halo" on red channel with Antlia filter

Acquisition Deep Sky M45 Artifacts Messier Objects
5 replies•247 views
Michele Campini avatar
Michele Campini avatar
He guys, i've a problem with Antlia filter RGB.
for the first time I tried to use these filters on some very bright stars (M45) and strangely with the red filter the spikes came out only in the brightest central star (Alcione) and I can't understand why.
These are 12 shots of 180 seconds per RGB channel with flat, dark flat and dark.
The camera is an ASI2600MM with ZWO filter wheel and the telescope is a 115/800 triplet with 1x dedicated field flattener.
Thanks for the help.

002_red.jpg
Aaron Hakala avatar
Aaron Hakala avatar
Kinda looks like the spikes from a bahtinov mask? Do you focus manually with a mask?
David Nozadze avatar
David Nozadze avatar
There might be a dust particle or even a tiny scratch on the red filtre surface. These are virtually undetectable, unles you are shooting a very bright star, like in Pleiades.

Very nice shot, by the way. 

Clear skies.

D
Respectful Concise Supportive
Michele Campini avatar
Michele Campini avatar
Aaron Hakala:
Kinda looks like the spikes from a bahtinov mask? Do you focus manually with a mask?


No, i don't use some spike mask, focus is with EAF.
David Nozadze:
There might be a dust particle or even a tiny scratch on the red filtre surface. These are virtually undetectable, unles you are shooting a very bright star, like in Pleiades.

Very nice shot, by the way. 

Clear skies.

D


Thank u David. But if there's something so small, I should have the usual problem in all stars, right?
David Nozadze avatar
David Nozadze avatar
Michele Campini:
Aaron Hakala:
Kinda looks like the spikes from a bahtinov mask? Do you focus manually with a mask?


No, i don't use some spike mask, focus is with EAF.
David Nozadze:
There might be a dust particle or even a tiny scratch on the red filtre surface. These are virtually undetectable, unles you are shooting a very bright star, like in Pleiades.

Very nice shot, by the way. 

Clear skies.

D


Thank u David. But if there's something so small, I should have the usual problem in all stars, right?


Not necessarily. I have a scratched Ha filter, but only some very bright starts will have spikes just like yours. That's why I thought this could be the root cause. But, ofcourse, I might be completely wrong. 

Here's my sample anyway:



and here are the scratches

Michele Campini avatar
Michele Campini avatar
Understood, i try check fine my R filter, Thank for now.