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Old 24-05-2018, 04:20 PM
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luka
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Red imaging filter issues

Hi,

Last night (for the first time) I tried imaging Jupiter with LRGB filters and ASI290MM mini on ED80. I was quite surprised how sharp the green- and the blue-filtered videos/stacked images came out, even from a 3" scope...

However, the red was all washed out and blurry, even the giant red spot on the planet was hardly visible in the stacked red image and not at all visible in the video. I checked multiple times and it was always the same with the red filter. The image was also significantly less bright than with the green and blue filters so I had to compensate with higher gain and exposure times.

Any ideas what is going on? I got the filters 2nd hand and never used them before. It is a set of old Orion filters, visually in great condition apart from a few dust specs. Is there any way to check how good the filters are without any extra gear?

I have attached a stacked and deconvoluted blue and red image so you can see what I am talking about.

Thank you in advance for any hints and suggestions,
Luka
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  #2  
Old 26-05-2018, 09:19 AM
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ZeroID (Brent)
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Because the Red filter is allowing red to pass it is showing only the red component of the whole planet on the mono image.
When you use the blue and green, because they only allow those components to pass through then the red spot shows as a darker area in mono as it has less of the blue\green.
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Old 26-05-2018, 11:49 PM
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luka
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Thanks Brent, that makes perfect sense (and I just had a D'oh moment... can't find an appropriate smiley though.)
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