Question on SNR

ghooper

Member
High SNR Weight is normally considered good. The first frame in the example below shows high SNR, but actually the frame is blurred by a light cloud film. In general I find that frames with high light pollution or cloud films receive high SNR ratings. Yet they should be poor candidates as contributors to the stack. Is my understanding incorrect? What advice can be offered on good weighting practice?

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Thank you, Gordon
 
they have high SNR weight because they are high SNR images - of clouds.

i think you should be able to weed these out by looking at the median values.

rob
 
they have high SNR weight because they are high SNR images - of clouds.

i think you should be able to weed these out by looking at the median values.

rob
Thanks Rob. This was what I suspected. The same applies to light pollution I imagine. Earlier frames, taken when the object is closer to the horizon also typically show higher SNR values, yet on visual inspection are clearly inferior frames. Thanks for the median tip, I’ll give that a go. Best, Gordon.
 
If not using SNR weight because of false results due to light pollution (or clouds), what is a recommended method for weighting?
Thanks,
Roger
 
SNRWeight is still useful... when there are clouds generally the star count is lower so you might be able to use the #stars as a means to reject clouded/hazy subs. personally i make a first pass thru blink to weed out any super obvious bad frames, then go into SFS with the rest.

rob
 
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