Star Trails

I've always loved star trail shots and want to start practicing this technique in my back-yard.

From what I have read on here it seems that the best way to do this and avoid light pollution problems is to take a series of 30 second shots and combine them. Most of the shots/examples I've seen are in the ISO 800, f/5 30s range which to me seems like it would add too much noise? Are there any ways around using ISO 800? Any chance I could use ISO 100 and still achieve star trails?

I've also read about continuous mode being used in conjunction with a remote shutter release, which I have and of course a tri-pod.

The biggest question I have, aside from exposure and ISO options are how I go about combining the series of 30 second images once I'm done shooting?

Thanks in advance for your help!

Haven't tried it yet, but I'm going too as soon as I get a clear enough night, but I've heard that the software from www.startrails.de is good for combining the pics once you're done.

Thanks for the link, I'll check that out when I get home

Hi there,

I use the software from Startrails.de, as it's dead simple and produces good results. 30s at ISO800 can be a little noisy, and there'd be no harm going down to ISO100 instead, but you'll capture far less stars. You might not want to capture too many as it can make an image a bit busy, but if you only grab the brightest stars it might be a little empty.

What I'd do if I were you is experiment. Take 30s subs at various ISOs and see what you capture. The one that looks the best, use that setting.

If light pollution isn't a problem for you then longer exposures might be the way to go. I peronally use 30s subs for several reasons. 1) I can leave the camera with the remote locked and go and do something else, (make sure mirror-lockup is off and burst-mode is on. I've gone away for half an hour once and come back to find the camera's only take one shot because mirror-lockup was on!!), 2) I do have a bit of light pollution at my site and 30s seems about right, and 3) I can put the images into an animation to make a starry timelapse video.

When you stack the images to make the startrail you reduce the noise. On the 20D I'd probably be quite happy using ISO400.

Adrena1in wrote in post #9488234
Hi there,

I use the software from Startrails.de, as it's dead simple and produces good results. 30s at ISO800 can be a little noisy, and there'd be no harm going down to ISO100 instead, but you'll capture far less stars. You might not want to capture too many as it can make an image a bit busy, but if you only grab the brightest stars it might be a little empty.

What I'd do if I were you is experiment. Take 30s subs at various ISOs and see what you capture. The one that looks the best, use that setting.

If light pollution isn't a problem for you then longer exposures might be the way to go. I peronally use 30s subs for several reasons. 1) I can leave the camera with the remote locked and go and do something else, (make sure mirror-lockup is off and burst-mode is on. I've gone away for half an hour once and come back to find the camera's only take one shot because mirror-lockup was on!!), 2) I do have a bit of light pollution at my site and 30s seems about right, and 3) I can put the images into an animation to make a starry timelapse video.

that video was awesome! What does the stacked image look like? I'm curious especially since you had some clouds and some light on the left side of the image.

hollis_f wrote in post #9488538
When you stack the images to make the startrail you reduce the noise. On the 20D I'd probably be quite happy using ISO400.

Thank you both for your responses. I do actually have a lot of light pollution where I live so I think the 30 sec subs will work well for me. I have had uncooperative weather though so I haven't been able to get any tests done. Last night I got home and it was fog. Rain is supposed to start up tomorrow so it might be a few days before I get a test done! I just wanted to gather as much info as I could now though!

theague wrote in post #9490061
that video was awesome! What does the stacked image look like? I'm curious especially since you had some clouds and some light on the left side of the image.

Thanks, I seem to remember stacking the images and it was rubbish, because the clouds covered most of the final result. (Another reason I vote for taking lots of exposures and having more than one option as an end result.)