Monday, April 21, 2014

1 Stock Footage Clip is Seeing Stars

Usually twice a year, the family and I travel about 90 miles outside of the city to a very small town in a valley to visit my wife's grandmother.  It is a wonderful place free of things like cell signals, which force you to be more "connected" to the people and things around you.  I've brought my camera down ever since I have started this blog in order to get star time lapses (something I cannot do in the light polluted city limits).  Since we don't go that often, rarely do i have a clear sky to capture (this was the only other one I've been able to get).  This past weekend gave me the perfect opportunity though and I was excited to employ the A/C adapter for my camera that tested so well during the "rotting banana" time lapse.  I also came this time with a much more scientific/mathematical approach to shooting vs. my previous star time lapse.

Most notably, I was able to put into practice something called the "500 rule" which is a calculation that you can perform to figure out how long you can keep your shutter open before you start to capture "star trails" instead of stars.  The formula goes as follows: 500/ (lens focal length) = max. shutter duration in seconds.  I was using my Sigma 24mm f/1.8 lens on my Canon T2i.  The Rebel line of Canon cameras has a 1.6x crop factor that needed to be included as well.  So my calculation was a followed: 500/(24 times 1.6) = 13.  So I had the max time my shutter could be open (13 seconds), I ended up dialing it back 1 second for safety.  Since I was focusing to "infinity" the depth of field did not matter on the camera, so I was able to keep it wide open at f/1.8.  These two known values allowed me to then dial in my ISO to something that would allow me a good exposure.  I settled on 800.  So for those of you interested, this sequence was shot RAW at f/1.8, ISO 800 and a shutter speed of 12 seconds.  I set the intervalometer in my Magic Lantern hacked firmware to 16 seconds, allowing my camera 4 extra seconds to write the RAW file out of the buffer to the 32GB card.  1,464 images later (or 6.5 hours) and what you see below is what I can offer you.

I plan on going back to the RAW files and trying my hand at creating a star trail time lapse by gradually stacking the images.  This is obviously something that will take a while, so I wanted to initially post this video for people who might be able to find a good use for it.  The lights on the trees are actually from trains that pass through town.  I was amazed that the images picked the light from them up.





  1. hm..tried to download onto Mac 10.7.5 but can't get it??

    1. Which format? (PhotoJPEG would be my suggestion). Are you seeing the file? Does a prompt come up when you Command + click the link? If you click the link directly, it will try to open the file directly into your browser, you need to hold down the command key and click the link for a menu to pop up. One of the options should be to save the link/file. Hope this helps!

  2. Thankyou so much for your talents and for offering this footage free of charge. I am a musician trying my hand at editing video content of the first time and it's been very inspirational not to mention affordable to "learn by trying". Best A

  3. Thank you again for this. Breathtaking