Photographing star trails

pressld2 · #1 (**permalink**) 21-10-2008, 10:39 PM

This is fun!

I've always been rather fond of star trail photos but very rarely get the opportunity. Here in the south east there's far too much light polution and a one hour exposure will give you a bright orange wash and not much else. But there is another way! In the last edition of Practical Photography there was an article on how to combine multiple images to get the same effect. I had a crack at it in my garden tonight and here's the result...

What you do is set your camera to continuous shooting mode, set the exposure to 30 seconds with a suitable aperture (I used f5.6) then use a cable release with a lock on it to set it going. My D300 will take a maximum of 100 shots like this but if I was there as it finished I could immediately set it going again.

When it had finished I put the lens cap on and took a final 30 second exposure as a dark frame for noise reduction, although as I was using ISO 200 the noise was not too bad anyway.

I was shooting in raw as I always do so loaded the shots into lightroom and exported them all as tiffs. Then the final stage is to combine them all into a single image. A very nice chap by the name of Achim Schaller has written a program to do this and it's available free from www.Startrails.de-Home. You can even watch the trails building up while it runs, which is fun!

When it's finished you can save the result as a tiff, jpeg or bitmap.

When viewed at 100% you can see that the lines are made up of a series of dots...

and this effect gets more pronounced as you get further away from the pole star. But even so, I'm dead impressed as I never thought I could get shots like this from where I live without a major power outage across the whole of Greater London!

Next step is to find something much more interesting than the top of my bay tree for the foreground...

Dave P.

Highlander71 · #2 (**permalink**) 21-10-2008, 11:05 PM

Dave, wicked pics, i've always wanted to try star trails shots but never got round to it. You may have inspired me to try.............when it finally stops bleeding raining!
You did say what lens you used for your shots?
Do you think the same effect could be achieved by doing an HDR merge in photoshop (or in my case PaintshopPro)?

Andy

pressld2 · #3 (**permalink**) 21-10-2008, 11:32 PM

I used a 16-85mm Nikkor right down at the 16mm end of the zoom.

A couple of other things I forgot to mention:

1. I had three aircraft fly past with blinking lights on their wings that I had to clone out of the final image.

2. You need a fair chunk of available disc space during the process to do it using raws and tiffs like I did. (If you shoot jpegs to start with it's not so much of an issue.) When I had all 101 raws and tiffs on my disc they came to very nearly 10Gb. I've deleted them all now and just kept one DNG version (11Mb) of the final image which I've imported back into lightroom

Don't know if HDR merge will do it. The magazine article says that you can stack the images on top of each other in Photoshop (I assume they mean using layers) and then change the blending mode to "Lighten". But they also say that with so many images to stack "this can prove tedious". I bet!

I hope you do have a go Andy (and I hope it stops raining soon!) If you do, don't forget to post the results here...

Dave P.

Highlander71 · #4 (**permalink**) 22-10-2008, 07:38 AM

Thanks for the info Dave. I suspect HDR merge won't work but worth a try. I did download the merge software you linked to but not sure it'll work on windows vista? Might end up trying to stack them manually..........if and when it stops raining (not a great deal of chance of that at the moment here!)

cutecoot · #5 (**permalink**) 22-10-2008, 09:00 AM

Quote:

Originally Posted by pressld2

This is fun!

Wow, this *does* sound like fun, Dave!

I remember (when I were just a wee nipper

) being absolutely fascinated when I saw how star trails could be photographed .. never quite got around to doing it though

This looks like a great way of doing it, so will give it a go sometime

pressld2 · #6 (**permalink**) 22-10-2008, 08:47 PM

Quote:

Originally Posted by Highlander71

not sure it'll work on windows vista?

I'm using Vista and it works fine - no problems!

I've only ever tried it twice, Cutecoot, once in Scotland and once in Canada. Both times I was using film and the Canadian ones were okay. I'll definitely be trying this again when weather permits. I've also realised that my camera was set to low speed continuous shooting at 3 frames per second. If I set it to high speed at six frames per second that should help reduce the dotted line effect that's visible when viewing the result at 100%

Dave P.

Hedge Witch · #7 (**permalink**) 22-10-2008, 08:55 PM

This is like a work of art, it's beautiful.

I also find the Bay Tree of interest. It looks so clear and in focus. Presumably it did not move much during the whole event - I mean in the breeze?

gess · #8 (**permalink**) 22-10-2008, 09:06 PM

This is really interesting Dave, only wish I had the know how/patience... maybe one day, will save your link tho, maybe one day...

Your results are great tho

Gess

pressld2 · #9 (**permalink**) 22-10-2008, 09:52 PM

Thanks both!

I was surprised at how well the bay tree came out too. It was a very still night last night but even so, I was expecting a bit more movement than that.

Dave P.

Highlander71 · #10 (**permalink**) 22-10-2008, 11:43 PM

Quote:

Originally Posted by pressld2

I'm using Vista and it works fine - no problems!

I've only ever tried it twice, Cutecoot, once in Scotland and once in Canada. Both times I was using film and the Canadian ones were okay. I'll definitely be trying this again when weather permits. I've also realised that my camera was set to low speed continuous shooting at 3 frames per second. If I set it to high speed at six frames per second that should help reduce the dotted line effect that's visible when viewing the result at 100%

Dave P.

Good news it works on Vista, i'll give it a try if it EVER stops raining here!