Help!! .. how do i get star trails?

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SimpsonBrothers

continous 30 second exposures, stack in photoshop change all layers to lighten.

r3t1awr3yd

Bulb mode.......

http://www.weatherscapes.com/techniques.php?cat=astronomy&page=startrails

Art Scott

here is something you might want to read........ http://www.danheller.com/star-trails.html

kdog

richy wrote: »

This

When taking the shots its probably best to use Tv mode set to 30 seconds then change the iso as a means of getting something around f11. A 50mm should do the job just fine. 30 seconds will give you a trail of a few pixels then as mentioned above you stack \ merge them in photoshop (or gimp, or psp).

You can buy fairly cheap remotes off amazon that have intervalometers in them which can be set to take X number of shots every X seconds \ minutes etc which can pretty much automate the whole thing for you to a large degree.

Alternatively you can use bulb mode if you have it and something like a 10 stop nd filter which I think would give about a 512 minute exposure from a native 30 second (unless my maths is horrendously wrong which it probably is), that might be way too long for the camera to cope with in which case you can also get them in 2, 4 & 8 stops and probably a few more and you can combine them to pretty much get any duration of exposure you need. FWIW I have no idea the effect of on the camera or battery of keeping a shutter open that long so others may wish to chime in on that before you try it.

F11? ND filters? TV mode? Richy, I ordinarily enjoy your posts, but this is completely wrong. I'm assuming you've never tried this and are speaking from a theoretical standpoint. But I believe you've miscalculated. If you're thinking in terms of not overexposing the stars, perhaps you aren't taking into account that they are constantly moving. They don't get brighter with longer exposure times using a stationary camera.

In order to photograph stars in general (not just trails), and using a stationary camera, one needs to collect as much light as possible. That means high ISO (ISO800 to 3200 range), and as wide an aperture as you can muster. F1.8 is fine. Maybe you could stop it down a bit to say F2-something to get it a bit sharper. But in general you want to shoot wide open. Stacking 30 second, or 1 minute frames works great and produces the cleanest images. But you'll need an intervalometer, or a lot of patience to accomplish this. However, one can even do a credible job using a bulb remote and leaving the shutter open for an hour. Use the in-camera long exposure noise reduction if you're doing the super long exposures. But don't use it on 30 second exposures, because it chews up too much time.

Here's a stacked shot, a few hours worth of 1 minute exposures.


Single long exposure with light-painted joshua tree.

Matthew Saville

Hibiscus Ink photography wrote: »

Hi I just bought a Sony 50mm f1.8 lens
Iv always wanted to get star trails and I was wondering will this lens pick it up...
and what is the best way to do this?

Back when I got into DSLR's, I got a tripod, went out at night, clicked the shutter and waited to see what happened. Try it! Go goof around!

The correct exposure will vary GREATLY depending on how much light pollution you have in your geographic area. For example, here in suburbia in Southern California, the exposure is 2-4 stops BRIGHTER than it will be in Death Valley when I go next week to photograph the upcoming lunar eclipse.

But either way, you'll probably have more trouble nailing focus at f/1.8, than you will have trouble nailing an exposure.

The trick to getting starts to "blur" (earth's rotation) ...is NOT to have a fast aperture, it is actually to have a super-long shutter speed. So you might find yourself at f/5.6 or f/8 even, depending on where you live. Then, try making an exposure for 30 seconds, 1 minute, 2 minutes, 4 minutes, 8 minutes, etc. ...And see how long the star blur gets!

Good luck,
=Matt=

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JC

You probably need an intervalometer, or timer. The 3rd party ones work fine - I don't know about Sony, but canon wants >$100 for theirs, and the $20 ones work fine for me.

If you live more than 100 miles from a medium city, a single long exposure will give you a semi-dark background, but if you live anywhere near a big city, a single long exposure on bulb is going to give you a significant sky glow with the star trails. Even at more than 100 miles from a big city, even if you can't really see the sky glow, your camera will on a long exposure. Kdog recommends high ISO- and if you want to get all the possible star trails for a really dense photo- upping the ISO high is one way to go- I usually shoot ~iso 200-400 though.

I like Matt's advice- there is no single formula that will work for all situations- just start playing around with it and see what effects you like best. Although even in Death Valley, he's got the potential for sky glow from Vegas on the eastern side of his shots- centered right about where the moon is rising, if he were to do a single long exposure.

With an intervalometer- you can take a series of shorter timed shots and stack them in post processing, which integrates the star trails, but not the sky glow. Most of my star trails photos end up at ISO 200-400, F/4.5-7.1, and I'm converging on 2 minute shots- it takes a bit of post-processing to stack them correctly and stacking 90 images is a pain in the gimp (there's probably a photoshop action that will take care of it easier, but I haven't figured out to program it in Gimp). Read this page http://www.naturephotographers.net/articles0509/fv0509-1.html for the screen then lighten blending technique.

So, if you are shooting in dark sky country- or like the neon sky glow effect, you can set the camera to bulb and walk away for an hour, or get a timer and program a series of timed shots. One advantage to timed shots, is you can time your series to start or end near moon rise, and then choose how much foreground illumination you want to keep in.

roakey

Sorry, since there's SO much information out there on the web on this topic, I can't resist: Let me Google that for you!

Roak

kdog

roakey wrote: »

Sorry, since there's SO much information out there on the web on this topic, I can't resist: Let me Google that for you!

Roak

Yes, there is a TON of information on the topic on the web, as there is for most topics, many of which contradict each other. None of that diminishes the value of an open discussion by our members here. A stronger and more relevant post by you would be to provide a reference to a technique and/or tutorial that you found particularly useful.