Thursday, March 21, 2013

Getting Started with Starscapes

Getting Started with Starscapes 
Guest Blogger: Aaron Coston, Editor of the Top Outdoor Producer


All dramatic star shots at night start the same way.  These stunning sequences of moving galaxies must be filmed with a DSLR.  Standard video cameras just can't reduce their shutter to a speed slow enough to expose the glimmering stars even on the brightest of nights.

Here we'll go through some of the most common equipment and tecniques used to produce many of the starscapes used by outdoor producers like Heartland Bowhunter and many others.


Camera Choice
With so many DSLRs to choose from, choosing one for photography at night can seem overwhelming.  For the best performance, get a camera with a full frame sensor like the Canon 5D MKIII.  The full frame sensor allows for better light gathering.  When your sensor is already gathering plenty of light, you can limit your ISO setting to cut down on noise, and you can slow the shutter a little if needed to reduce the amount of streak in the stars.

That being said, many great shots are captured at night with crop frame sensor cameras like the affordable Canon 7D, Canon 60D, or the Canon T4i.


Shutter Speed
So how slow does your shutter need to go?  Some video cameras like the Sony AX2000 can reduce shutter speed to around 1/4.  Thats slow.  Most anything filmed at that speed will result in streaky unusable footage. But, to expose the dark night sky, your shutter must be open anywhere from 10 to 30 seconds.  120 times slower than the slowest setting for the AX2000!  After 20-25 seconds stars will actually resemble small streaks in the sky rather than a bright dot.  Remember, the earth is spinning, and that movement will show.

In addition to shutter speed, normally you'll need to open your Iris as wide as possible. So, a lens that allows for a lower Fstop is a big plus.   The shot to the side here was taken with a standard 18-50mm at f3.5.  Having a lens with me that could have gone down to f2.8 or lower would have helped gather more light, but at the time the f3.5 is what I had.



So, now you've got your Canon 5D MKIII, the shutter speed is stupid slow, and your lens is set wide, and your iris is wide open.  Now its time to pick an ISO.  ISO works like gain on your video camera.  It helps gather more light, but it does so at a cost.  Noise.  And, noise is especially visible on a black background (ie dark sky).  So depending on the camera you use, and how it performs under high ISO, play around with it and see what your images look like.  On full frame sensor cameras (like the Canon 5D MKIII), ISO 3200 isn't crazy.  On crop frame sensor cameras (like the Canon 7D, Canon T4i, or Canon 60D), you'll have to tone that down a bit.  The only way to find out what works best for your camera is to try it.



Support
When your shutter speed is this slow, tripod support isn't an option.  Its a necessity.   I use a heavy tripod that was built for video.  Its big, beefy, and when I set it up, its not going anywhere.  Even physically actuating the shutter release can cause enough shake to result in a ruined photo.  Because of this, using a timed shutter release or a wireless remote is highly recommended.

But, you're support doesn't have to stay still.  Through the use of motorized timelapse dollies, pan heads, and jibs, producers are able to create over the top dramatic starscapes with motion.  For more information on that, click here.


Making a Movie
Here you are.  You've got your 5D running wide open at ISO 1600, and you're getting ready to order a full resolution print for your living room.  Now how do you turn a still image into a movie?  With lots of still images.  But, standing over the camera, constantly firing off the shutter release doesn't sound fun does it?  Enter the intervalometer.  An intervalometer is a remote control.  It plugs into the camera, and tells the camera to shoot.  Not just once, but as many times as you tell it to.  And, you can also set how much time to leave in between each shot.  For instance, anyone can plug an intervalometer into a Canon 5D (or 7D or 60D or T4i), and set it to take 500 images with 10 seconds between each shot.

Take this folder of images into your editing system or software made for assembling timelapses, and when they're all set to show for 1 frame side by side, you have a movie.
Keep in mind here not to let all the basics of photography fly out the window.  Do what you can to frame  the shot well.  Try and incorporate some foreground subjects.  Don't just shoot the stars, make the shot interesting.

If you live in town, drive far far away to try these shots.  The light pollution from town will make getting a solid image impossible.  The shot above with the Lighthouse rock formation was taken from a location 30 miles south of Amarillo Texas.  Even at that distance, the light is clearly visible among the clouds.

But, the most important thing you can do to learn more about shooting stars (play on words there), is to go do it.  Get out there, create some images and post them on our Facebook page! 

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