Wednesday, December 27, 2006
Stack 'em up!!
One thing I learned & loved very quickly was the technique of stacking many exposures to increase the signal-to-noise ratio. Things like light pollution and a mount with less-than-perfect tracking all work against us to limit how long we can take an exposure. If you can't take 10-minute exposures, no problem. You can take 2 or 3 minute exposures and take lots of them to get almost the same results. Software like ImagesPlus makes this task easy and offers many different options to stack images. I still don't understand them all, but the results clearly speak for themselves. Take a look at what happens when I add 20 more 90-second exposures to the 10 I took the night before (top picture). Nice improvement! And then look what happens when I add another 30 exposures.The results get even better - now I have dust lanes appearing in my Andromeda Galaxy. This is where I realize that I didn't line up my camera very well on different nights. You can see the mis-alignment on the corners. Oh well, all part of the learning experience. I'll keep going back to this object and adding more exposures.