Stacking duplicated Images

[SB]

Hi All,
I have often wondered instead of taking ( for example) 100 subs you take 10 clean dithered subs and then duplicate these 10 times and then stack? After all the reason for taking multiple subs is to reduce the SNR. Wouldn’t duplication of a few subs do the same?

Thanks

Chris

[Dennis]

Hi Chris

When you take many subs, each sub has the (desired) real signal for the object(s) you are imaging and the (unwanted) random background noise from heat, electronics, seeing, etc.

When you align and stack several subs the "fixed" real signal is reinforced and "adds up". The noise, which is random, is reduced as it varies from sub to sub.

If you only have a single sub and add it to itself, the random noise is in the same position on and will therefore also add up and not reduce.

Cheers

Dennis

[multiweb]

That'd be great though :lol:

[glend]

If it worked some sort of magic, people would have been doing it for decades. But go ahead and try it yourself, and publish the results here. It is good to touch on this subject now and then.

[Startrek]

There’s loads of information on the topic in the CN forum
From what I’ve read , your stacked image with be the same as your single sub
ie: no improvement in SNR

[RB]

He’s just asking a question Glen.
Dennis summed it up nicely.

RB
:thumbsup: