SADR y-Cygni

[roberto_volpi]

Hi
An other H-alpha image captured last week from my sub-urbane site.
Roberto

4 Hours (12x20') binning 1x1
AstroProfessional Apo Triplet 115/800
Sbig ST2000XM
7nm Baader Planetarium Ha filter
SW Eq6 Pro Mount

[Lex]

Roberto,

nice image again, processing is really allright but there is one thing that disturbs in the image...
The diffraction spikes of the biggest star are to pronounced for me..
There is a strange artifact, in the spikes, some kind of up and down; i think this comes of nylon wire used for achieving those spikes...
Did you already try to take pictures without those DS?

BTW, this is only my personal opinion 

Best

Lex

[roberto_volpi]

Hi Lex, thanks for the feed back.
I think that the problem is the discontinuos spikes, tipical of Ha on big stars. I should have done same frames with luminance filter to correct Sadr spikes, the next time
Roberto

[zvrastil]

Hi Lex, Roberto,

very sharp diffraction spikes of bright like Roberto have will contain rainbow pattern on RGB image. On Ha, just red part of the rainbow gets recorded, producing dashed pattern. As long as you have someting in the optical path producing spikes, I don't think there's way to avoid it.

cheer, Zbynek

[Lex]

Hi,

i agree with you that the colors are coming with the different filters.
I did some testings with nylon wires painted in black and this reduces kindely this artefact, just to say 

best