star trails.....how to do it.

[azpix]

i'm heading out to some remote areas away from the city and thought i might try and shoot some star trails for the first time.

besides long exposures and a tripod, what else would i need to know? any tips and tricks from you experts?

thanks all.

[silvrr]

No expert but with a steady tripod do a series of shorter exposures ~30sec and stack them in photoshop. This will avoid any non sky areas from getting blown out and produce less noise.

[azpix]

interesting. I would have thought is was one long exposure.

how hard is it to blend the 30 second photos in PS?

[Sorarse]

Really easy, or you can download a piece of free software that does the job for you. Can't remember what it is called, but someone will be along soon to tell you.

Blended shorter exposures will give you a much better result than a single long exposure, so it's worth taking the extra effort to achieve.

[azpix]

How many 30 sec exposures should I shoot for?
is there a trick to do this? can i set the camera ( a 40d) to continuously shoot a 30 sec exposure?

[A.S.I.G.N. Observatory]

Here you go mate, this might help.

http://www.asignobservatory.com/widefield_and_time-lapse.aspx

And heres the stacking program for star trails.

http://www.startrails.de/

If you take a 30 second exposure at say, 18mm, then you should get a pretty good shot with no real elongation of stars. If you go for a 5 minute exposure, you will start to see the trails as the stars get longer. 10 minutes should show much longer again, but you have to be wary of how much light pollution is about or it will wash out the photo and render it useless.

If you are a long way from a city, then you can go for the longer exposures.

The beauty of the startrail.de program, is that you can take a heap of nice contrast 30 second exposures, and stack them together to make a startrail.

If you look on the first page I sent you, you'll see there is a a device I use called an intevalometer. You can set this to take your exposures all night.

Baz.

[tunin]

Dude, the two links you posted were great help. Thank you.
:D
Here you go mate, this might help.

http://www.asignobservatory.com/widefield_and_time-lapse.aspx

And heres the stacking program for star trails.

http://www.startrails.de/

If you take a 30 second exposure at say, 18mm, then you should get a pretty good shot with no real elongation of stars. If you go for a 5 minute exposure, you will start to see the trails as the stars get longer. 10 minutes should show much longer again, but you have to be wary of how much light pollution is about or it will wash out the photo and render it useless.

If you are a long way from a city, then you can go for the longer exposures.

The beauty of the startrail.de program, is that you can take a heap of nice contrast 30 second exposures, and stack them together to make a startrail.

If you look on the first page I sent you, you'll see there is a a device I use called an intevalometer. You can set this to take your exposures all night.

Baz.