Image stacking and exposure time
I have been imaging for about 1-1/2 yrs now, typically using a fork-
mntd, alt-azth driven 8"SCT at f3.3, using a color CCD camera (Orion
Starshoot), and doing basic image adjustments with Corel's PaintShop
ProX. Samples of a few images are shown in "Victor's Images" photo
I have obtained fair results by capturing multiple, short-exposure
(15 to 25 sec) images and stacking 20 to 30 samples. Brighter
targets such as M20 yield best results, although fainter targets such
as NGC6995 still show resonable color rendition. However, other
faint targets such as NGC7635 fail to show significant coloring with
these short exposures - in spite of efforts at image adjustments.
Is the individual image exposure time the controlling factor in
recording colors? Basis my results, I suspect that the improved
signal-to-noise ratio obtained by stacking images also increases
color rendition, but have found little on this subject by searching
the net - perhaps I am not asking the right questions.
I am fully aware that in order to capture longer (e.g., beyond
20sec/image) exposures I will have to use a polar-aligned scope
(e.g., wedge for my unit) and invest in autoguiding hardware. For
now, I am just having a good time with the simpler setup.
Thanks in advance for you comments.