I would like to take some pics of the sky. I wont be able to get much cos I dont have a scope and I dont have a driven mount for my camera. (I dont know whether to save up and get my dream lx200, buy a cheapo ETX 70/80 or a DS2090. Or give the double arm scotch mount a whirl) anyway, thats another topic for another day!

My question is this....
How long can an exposure be before the star/point of focus starts to trail?

I know I could do some test shots but I will struggle with focusing and that will blur my stars on top of any trail. I want to get round my exposure time head scratch first.

I know the stars will certainly move during the session as a whole but I can fix that. If my frames are smudged its game over.


Ive only ever used a 12" LX200GPS with a posh ccd and also spectrmeter. That was at OAM on Mallorca about 4 years ago..... I had my very first go last night with my camera and this is what resulted. Im quite happy it. I only took one batch of pics and had one crack at reducing the data. And to throw a spanner in the works my tripod mount slipped during the exposures. It slipped so much that the moon didnt even overlap when you compare the first frame to the last. I was stunned when it still matched up ok!

Moon
9/12/08 21:33 approx 0'c
Canon 350d w/Canon 90-300 @ 300 (£30 ebay jobby)
30 frames of 1/1000s f5.6 ISO200
5 dark frames of 1/1000s
Reduced and combined in MaxDSLR.... only one High-pass kernel sharpening filter was used. I used Planet Stretch.
Cropped and reduced to 75% of original
http://www.bautforum.com/picture.php...&pictureid=382