Hi everyone,
Looked through the archives, but couldnt find what i was looking for so...
Been doing some research on other sites about total exposure length of a single 60 min sub vs say... 10 - 6 min subs as to which one would be deeper and how the signal:noise ratio (SN) compares. One such thread here
http://cs.astronomy.com/asy/astro_im...5/t/49285.aspx, asks a similar question - which is the longer exposure time, 10 x 6min subs combined or a single 60 min sub. So which final calibrated image would have captures more data? does this depend on weather the subs are averaged or summed?
One member on the above forum says either way, its still the same amount of total exposure time both ways - which i would agree with, however, which exposure method would give the deeper image or pixels with higher readings (for signal that is)?
When you hear an image has been "summed" is it refering to adding ie. 2+2=4? or is adding just a loosly used term? If this was the case, would the pixel values of the final stack of 6 sub exposures summed in this way have 6 times the pixel value of 1 sub (talking about photon signal here)?
Then when you combine by the median or averageing method, I would imagine the pixel values, from signal, in the final stack would be much closer to those in a single sub exposure because the pixel values have not been summed... they have been averaged - for example?
If pixel were summed as in addition and you exposed to half your full well capacity, then summed 3 subs together, would this then overexpose that area of sky?
Some of these paragraphs contradict because of my uncertanty of how it works.
Thanks for any advice
Josh