« on: May 17, 2013, 03:02:32 PM »
I've used a 40D for night sky time lapse a number of times, I spent years doing astrophotograpy with film and do NOT miss film AT ALL.
Tokina 11-16/2.8 (usually set to 3.5). RokSamBow 14 would be a nice substitute.
ISO 1600 (3200 is noisy), Raw.
WB either daylight or custom, gets tweaked in PP anyway. The kinda brownish tinge you can see from long exposures in non-light polluted areas is really the color of the night sky, it seems jet black to our eyes because we can't detect the color and our brain expects it to be black. The camera doesn't lie. Incandescent WB can counteract that but affects star colors.
15 seconds exposure, 5 seconds off, yielding 3 exposures per minute
25 seconds exposure, 5 seconds off, yielding 2 exposures per minute
Off times allow for image saving to card and help a bit to keep sensor heating down
17mm f4 should let you get away with 25 second exposures easily, I'd be more concerned with the IQ of the lens wide open
PP in Lightroom. A free program that can also be used is Startrails....but you're shots will have to be good, it doesn't do any tweaking, just generates a video or a startrail shot
Hands down, the single toughest issue I have is dew on the lens, it has ruined more sequences than anything else. Have fun, but understand it can be a gateway to motorized mounts, telescopes and other appurtenances that will suck the life out or your wallet and nights. Sure is enjoyable, though.....