Beginner’s guide to astrophotography

Starry night in the Colorado Rockies
Being able to produce vibrate images of stars is the main reason I picked up my first professional camera.  I’ve always been fascinated with astrophotography and just in 6 short months I’ve learned a lot about it.  Obviously 6 months is not nearly enough time to consider myself an astrophotography expert but there are 8 tricks I picked up over that time that has drastically improved the quality of my starry photos.  As a prerequisite I’m going to assume you already have a basic understanding of how to adjust your camera’s settings and a general idea of what the exposure triangle is.

Aperture settings

When first starting out I read that aperture controlled my depth of field.  So a low F-stop number would create a blurry background while focusing in on the subject, and a high F-stop number would make everything in focus.  Naturally I went for the highest F-stop number, but not realizing that this also let in the least amount of light.  When shooting the night sky this is the exact opposite of what we’re looking for.  It’s crucial to increase the size of your aperture by setting your F-stop number to the lowest value possible.  Depending on the type of lens you have this would probably be somewhere around 2-4.

Shutter Speed

Now that our aperture is set to let in the most amount of light as possible we want to capture that light for a longer period of time.  Most DSLR cameras today will easily let you increase your shutter speed to 30 seconds but that doesn’t always mean you should.  While 30 seconds will render you the brightest stars, it could possibly make your picture more blurry.  Believe it or not, 30 seconds is generally enough time to make the stars blurry in your picture due to the earths rotation.  The amount of blur is usually pretty nominal but if you find it too distracting, try starting at 30 seconds and work your way down with 15 seconds typically being the lowest I’ll go.

ISO settings

ISO can really help your stars pop, but it will come at a cost.  As you might have heard, as you increase ISO, you introduce more grain into your photo.  You can remove some of this in post production, but ultimately you’ll want to nail your picture settings as best as possible in camera, and leave as little of work to do in post as possible.  Generally speaking I’ll start my ISO at 1,600 and will go as high as 6,400.  This can really vary based upon your camera.  I have a Sony A7 which does pretty well with higher ISO settings, but if you have an older camera or one that doesn’t work as well with low light scenes you might be stuck with a lower ISO.

Steady tripod

It’s more or less impossible to create quality star photographs without a steady tripod or surface to place your camera.  Since your camera is going to have it’s shutter open for 15-30 seconds, even a fraction of a millimeter in movement will make your photo extremely blurry.  Shooting on a tripod is a must!

Cable release or timer

A cable release is basically a way for you to control your camera’s shutter without actually having to touch your camera.  You plug it into your camera and at the end of the cord is a button you can press that will take the picture for you.  Why is this important?  Like I said before, when you have a shutter that is open for such a long period of time, any movement will distort the photograph, and that includes the pressure you put on the shutter button to take the picture.  Personally, I don’t own a cable release yet, so I just set my camera to use a two second timer and I believe this works just as well.

Manual focus

So you’ve nailed the aperture settings, got yourself a tripod and are using a timer but your pictures are still coming out blurry?  Using the camera’s automatic focus for astrophotography will simply not work.  When using automatic focus the camera needs a subject to zero in on, and when it has nothing but a 1 pixel star as it’s focal point it will never pick it up.  My recommendation is to put your camera in manual focus mode, find the brightest star in the sky and turn your focus ring until you can make that star as clear as possible.

Shoot in raw

You spent the money on an expensive DSLR camera, don’t waste that money by shooting your pictures in JPEG.  No matter if you’re doing astrophotography or just some portraits, I can’t think of a time where you would ever want to shoot in anything but RAW.  RAW photographs carry so much more data that you won’t instantly see on your camera’s display, but will definitely notice when you bring the photo in for editing.

Location & timing

Last but not least is location and timing, which could quite possibly be the most important tip.  Ever seen the milky way in NYC?  Yeah, I didn’t think so.  It’s a well known fact that stars are just not visible near city lights, and to get the clearest night skies we need to shoot in the darkest locations we can find.  There are a bunch of sites and apps out there that will help you find a good location, but I like to use DarkSiteFinder.com.  Now that you have a dark location to shoot, you’ll want to check two more things, the phase of the moon, and when the moon will set.  Just like the city lights wash out a starry sky, a full moon can do the same.  You can get away with shooting during a full moon so long as you shoot after it has dropped below the horizon.  To find out that information check out TimeAndDate.com.

Bonus!

If you want to take your astrophotography to the next level, it might be time to shell out some cash for a super wide angle lens.  When shooting something as vast as the night sky it’s important to get a lens that can capture a wider field of view.  One additional benefit to getting a super wide angle lens is that they will generally have larger apertures which we now know will increase the amount of light we can let in.  The more light we can let in, the more detail we can get from the sky allowing us to lower our ISO and shutter speed and ultimately create clearer pictures.