Wednesday, May 11, 2011

A new perspective on star trails

I have always shot star trails with a fisheye or ultra-wide angle lenses.  It just seemed to make sense.  More sky would equal more stars.  I tried shooting star trails at a longer focal length and was pretty happy with the new perspective.  Read on to learn why...
85mm @ f/1.6 ISO 1600 for 240 seconds.
now compare the same tower viewed through a 15mm fisheye

15mm fisheye @ f/2.8 ISO 3200 for 40 minutes
85mm @ f/1.4 ISO 400 for 30 minutes
I had been to the location and shot star trails there on multiple occasions before.  I got there this time and was bored before I even started shooting.  Was I going to shoot the same pics again?  No way.  Why not try something new.  I got my camera out from the car which had a 70-200mm already mounted on it.  I had planned on a few snaps of the moon so I put it on before I left the house.  As I looked around the same old location through the longer lens I became excited at what I saw.  I did not see the same old location.  I saw a new location.  I saw things I did not know were there and all of a sudden I was not only seeing differently but thinking differently.  So, I slapped an 85mm on, pointed that at a nearby radio tower and started it shooting for a stack.  I threw a 135mm on a second body, pointed it at a farther tower and got that shooting for a stack.  I decided I had better set up a trusty old wide angle shot as well because really who knew how those longer shots were going to turn out because they were just experiments.  So a third camera got shooting a stack.  I thought I better have at least an insurance shot or two.

135mm @ f/2 ISO 1600 for 18minutes
I wrote a chapter for a book that was published in 2010 on shooting star trails.  I mentioned in that book that a longer focal  length would make the trails look longer in relation to the frame than a wider angle would.  At that time I had only tested some shots at 50mm and found that I could get decent trails in a relatively short amount of time.  They were not longer as the actual length is based solely on time but they appeared longer.  So when I had finished setting up the third camera I went and stopped the the first camera with the 85mm on to see where it was at.  I flipped through the images and was really surprised by how much the stars had traveled in a relatively short time.  I had not seen what they looked like stacked but by looking at the first frame and the last frame it was obvious that they appeared to have traveled quite far.  I left the camera with the 135mm on stacking for 50 minutes and it produced the same results.  I should add though, that the stack shot at 135mm had tiny gaps between frames that were visible when viewed large.  The smooth trails of a wide angle had become a finely dotted line.  The image on the left is the same tower at 135mm but what you see is only 18 minutes.

85mm @ f/1.6 ISO 1600 30s.  1 frame from the shot below
One last benefit I noticed was that shooting at these longer focal lengths reduced the time needed for each stack making the whole night more productive in terms of images I was going to get out of it.  With a wide angle each stack needs time so there is a lot of standing around drinking beer which actually does not sound so bad when put like that but it often meant that 2 or maybe 3 stacks could be done on a good night.  The longer focal lengths were able to get long trails in relation to the frame in a short time meaning that I could take several stacks in one night per camera.  That meant it was one very productive night for stacking.
85mm @ f/1.6 ISO1600 for 10 minutes
What did I learn that night?  Looking at the same old location through different lenses provided a whole new perspective and a bunch of new ideas and inspiration.  All those locations I got bored over the past few years can be revisited with a whole new set of ideas and inspiration.  Longer focal lengths were great for shooting stars!  They were able to capture long trails quickly and are not the typical wide angle view.  4 Minutes at 85mm would yield trails where 4 minutes through a fisheye would still only be a bunch of dots.  And to top it all of the night was incredibly productive.  I was able to shoot more images than I had ever shot in one night before.

Any questions or suggestions?  Hit me up in the comments!


Pricing said...

Interesting observations! Looking forward to trying this when we get clear skies...maybe in a month or two..

Chris Lane said...

Brilliant post Trevor. I found you via DIY photo blog. This post is a good essay on what everyone should be doing with their photography all the time. I think its always important to get new perspectives on everything and you definitely got some great results in the process.
I have yet to take star trail photos but its definitely on my to do list. Especially after reading the diy post and this one. Thanks for sharing!

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