Reflections/Star Halos with ALP-T Sii&Hb 5nm Antlia ALP-T Dualband 5nm SII&Hb 2" · Mau_Bard · ... · 6 · 295 · 1

Mau_Bard 2.11
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After using with great satisfaction the normal Antlia ALP-T filter (Ha+Oiii), I decided to buy in addition the Antlia ALP-T (Sii+Hb) in order to produce SHO images.

Unfortunately my specimen of ALP-T (Sii+Hb version) produces the dramatic reflections that you can see in the unprocessed images attached here. Both images have been taken with the same equipment on the same night (Newton 200mm f/5, camera ASI2600MC-Pro).
I got similar reflections on different targets previously.

Has somebody had the same experience? This is happening specially in presence of large stars.
Any idea to fix this? Thanks in advance for your suggestions.

Left image: ALP-T (Ha+Oiii)
Right image ALP-T (Sii+Hb)image.png
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andreatax 7.90
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There is a method to remove this sort of halos but I never used for multiple reflections of the exit pupil. So the prognosis is infelicitous but I can give it a go (if I have the file, that is). The only sure fire solution is to move the filter down the imaging train, ideally before the CC but this may not be very practical. 

Return the thing, if you can.
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Mau_Bard 2.11
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Ciao Andew, thanks for your remark. It is strange that the "normal" ALP-T is producing virtually no reflection while its Sii+Hb brother is making such a huge one.
After writing this post, I had the thought that Antlia has mounted the filter reversed into the frame. I can check it turned upside-down before delivering it to the trash bin.

Honestly I am pretty surprised that an expensive and good-reputed brand like Antlia is releasing such a grossly defective product (at the cost of 560 Euro, by the way...).

If I well understand you have a methodology to try and correct this reflection? If yes, may I send you the file in a private AB-mail? I appreciate it won't be easy...

Ciao, Mau
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andreatax 7.90
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Ciao Andew, thanks for your remark. It is strange that the "normal" ALP-T is producing virtually no reflection while its Sii+Hb brother is making such a huge one.
After writing this post, I had the thought that Antlia has mounted the filter reversed into the frame. I can check it turned upside-down before delivering it to the trash bin.

Honestly I am pretty surprised that an expensive and good-reputed brand like Antlia is releasing such a grossly defective product (at the cost of 560 Euro, by the way...).

If I well understand you have a methodology to try and correct this reflection? If yes, may I send you the file in a private AB-mail? I appreciate it won't be easy...

Ciao, Mau

Spedisci pure, Maurizio. Nessun problema.
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Mau_Bard 2.11
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Grazie Andrea!
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rroesch 1.20
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Hi 
I had the same issue with my Dual band and RC, one thing It make a big impact was the position of the filter. I got a similar reflection when I put the filter in a filter drawer which was positioned on top of the reducer/flatterer. when I screwed the filter in the back of the flattener, the reflection went away
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Mau_Bard 2.11
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Ciao Rodrigo, thanks for your message and experience!
My optical train is (following the direction of incoming light) coma corrector > filter wheel > camera
I am not sure I understood your configuration before and after. You had initially the filter initially between scope and reducer? And afterwards you moved it between the reducer and the camera? Or was it the other way round?
Thank you!

Maurizio
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