Anyone got ideas what might be causing a Halo around a bright star on Green and Blue Filters ?
I took some 10 min exposures tonight gathering color data and I noticed my Green and Blue filter exposures had a bright halo around one of the saturated stars.
I have attached a picture.
The red filter does not have this. They are parfocal Astrodon Gen 1 filters.
Reflections off the filters. Gen 11 have anti reflection coatings as most scopes these days have correctors and especially with the larger chips reflections became a real issue.
I used to get reflections like that sometimes with green. Occassionally with blue. These are mirrored type filters. Also do you have them facing the right way? Mirrored side towards scope?
Thanks Greg. Never knew there was a right way around. Will double check the installation of the filters.
Quote:
Originally Posted by gregbradley
Reflections off the filters. Gen 11 have anti reflection coatings as most scopes these days have correctors and especially with the larger chips reflections became a real issue.
I used to get reflections like that sometimes with green. Occassionally with blue. These are mirrored type filters. Also do you have them facing the right way? Mirrored side towards scope?
Hello Chris, many interference filters show similar hallmarks, and while AR coatings help, reflections can still pop up from deeper down in the filter.
( FYI some narrow band filters have 64+ layers)
They are also spectrally localized....and can get worse at the peak QE wavelength of your camera.
There is usually no easy fix, other than to try another filter or manufacturer. Making sure your filters are exceptionally clean also helps.