n00b to Star Trails

[PhatheadWRX]

Over the holiday, I'll be camping out far away from city lights. I thought it may be a good opportunity to get some star trail shots.

Does anyone have any tips or a starter crash course? Should I stack multiple exposures (w/o in cam NR) or try a single exposure? I'm thinking of shooting with my 18-55 @ 18mm, ISO 100, f/4. The data shows a 1% crescent moon for Wed.

Would the best technique for a single exposure be to ramp up ISO to get a good test exposure, then lower the ISO and increase time?

Does stacking reduce noise? I do not have a timer release unfortunately.

[Adrena1in]

Personally I would go for the multiple-shots-stacked technique. Less noise for a start, and easier to do some test shots to get the right level of brightness and any background contrast. My longest so far was 12-minutes, and I stacked two images, but the noise was pretty bad. I know it would be possible to subtract dark frames to remove the noise, but that's just another step which can be avoided if you stick to only a minute or so for each exposure.

Would really be worth trying to get a remote shutter release though...a tiny nudge on the camera could cause some frames to be a little out of line, even at only 18mm.

[PhatheadWRX]

I have a remote shutter release, just not one with a timer ;)

Thanks for your comments

[ChrisRabior]

http://www.danheller.com/star-trails

Worth checking out. I tried it, got some pretty nifty results on a trip to the upper peninsula in Michigan.

[Adrena1in]

Oh right, if you have a remote then no problem. Just set the camera up, turn off Mirror Lock Up and the Long Exposure Noise Reduction, set it to burst shooting mode, set it to 30" exposure, then lock down the shutter release and sit back as it snaps away every 30-seconds. One or two hours of this will give plenty of nice images to stack.

One tip...many people agree that getting the Celestial Pole into the image makes it a little better. You can see the point around which all the other stars revolve.

[PhatheadWRX]

Thanks, that sounds like a great idea.

turn off Mirror Lock Upshould I disable (default) or enable mirror lock up to avoid shake?

[Adrena1in]

If you have Mirror Lock Up enabled then it won't shoot multiple images by locking the remote release down, that's all. At short FLs and long exposures mirror-slap isn't really a problem anyway.

[PhatheadWRX]

thanks for the clarification