Photo by Jamie Anderson

 

Astrophotography 101

By Jamie Anderson

When people see an awesome photo of the night sky or the Milky Way, the first thing they typically ask is, “What camera settings did you use?” Well, that’s certainly part of the equation for doing this type of photography, but there are a few other considerations as well. Let’s take a quick look at seven tips for taking great night sky images.

First, you should know that you probably already own most or all of the photo equipment that you’ll need for these shots. Most images can be created with a single long exposure. All of the photos in this article are either single-shot exposures or panoramas of single shots stitched together.

Photo by Jamie Anderson

 

LOCATION
To begin with, you need to find a dark location, and the darker the better. Getting away from city lights is a necessity, because there is simply too much ambient light in urban areas to see the stars. In fact, a single streetlight in the area can spoil your attempt. All of the light generated by manmade sources (sometimes referred to as light pollution) will block your view of the stars and, in particular, the Milky Way. DarkSiteFinder.com is a helpful website that can help you find dark sites (see https://darksitefinder.com/maps/world.html#4/39.00/-98.00). On this map, you can see the problem with light pollution in the eastern United States. But take heart, it’s not impossible. On the east coast of Georgia for example, communities keep the lights dimmed so the sea turtles will come ashore and lay their eggs. Also, we’re often pointing our camera to the east, southeast or south to capture the Milky Way. This is away from the city lights and out toward the darker ocean.

TIMING
The best time for star photography is during the new moon. During this phase, the moon is actually in front of or near the sun. So at night, the moon will be out of the way. A full moon, on the other hand, can ruin your shot if you’re attempting star photography, because its brightness will overwhelm the night sky. (However, a photo of the full moon itself can be pretty impressive in its own right). For Milky Way photography, you’ll need to know when the Milky Way is up at night. In particular, you’ll want to know when the “galactic core,” which is the brightest part of the Milky Way, will appear in the night sky. It rises and sets like the rest of the celestial objects in the sky. In the early spring, early-morning hours are best. At midsummer, midnight to early morning is best. In early fall, about 1.5 hours after sunset is prime time. In the winter, unfortunately, the galactic core is actually up during the day and sets before sunset. So spring through fall are the best times for photographing the Milky Way.

CONDITIONS
Obviously, you need clear sky conditions in order to see the stars. Even a partly cloudy night can ruin your view. However, if the weather report says “mostly clear,” it may be okay. Sometimes the clouds dissipate at night, and an incoming cool or cold front can clear away the clouds, creating great opportunities. You may just want to step outside the house and look up at night to see if the sky is clear. If you can see stars in the city, you’ll see a lot more when you get to your dark location.

EQUIPMENT
Here’s a list of some of the equipment you’ll need:

  • Camera body that works well with high ISO (in the 3200 range)
  • Wide-angle lens with a wide (fast) aperture in the f2.8 range
  • Sturdy tripod (think long-exposure photography)
  • Shutter release (optional, for taking the photo with hands off the camera)
  • Flashlight
  • Normal stuff for photography – spare batteries, cards, lens cloth, etc.

Photo by Jamie Anderson

 

EXPOSURE
To figure out the proper setting for your camera and lens, let’s start with the 500 Rule:

500 / Focal Length / Crop Factor = Maximum Exposure Time (in seconds)

The 500 Rule estimates the maximum amount of time that you can expose your camera for the stars at a certain focal distance before “noticeable” star trails begin to occur from the earth’s rotation. Yes, with this type of photography, you can get noticeable camera movement just from the rotation of the Earth! Of course, “noticeable” is often a matter of opinion and varying degrees (“barely noticeable” to “very noticeable”). As with all mathematical equations, an example can help. Let’s use the equation for a 24mm lens and a full-frame camera. So, 500/24mm = 20.833, or about 21 seconds maximum exposure time before “noticeable” star trails begin to occur. If I have a Canon crop-sensor camera, on the other hand, I would need to divide the 21 seconds by a crop factor of 1.6 (the Nikon Crop Factor is 1.5). So, 500/24mm/1.6 = 13.02, or a maximum exposure time of about 13 seconds.

THE OTHER SETTINGS
Ideally, minimum settings at 24mm are f2.0, ISO 3200, and a 20-second exposure. These settings on a full-frame camera body will work really well. However, if you can’t meet just one of the settings, you’ll need to adjust something else. For example, what if your lens only goes down to f2.8? A movement from f2 to f2.8 is a full “stop” of exposure, which cuts your light in half. So, in order to compensate, you would need to double your exposure time to 40 seconds OR double your ISO to 6400. A good compromise might be to increase exposure to 30 seconds and adjust your ISO to 4000. If your lens aperture will go to f1.4, that would represent a full stop from f2.0 and provide twice as much light. You could then decrease the exposure time to 10 seconds OR adjust the ISO down to 1600. The good news is, once you find the correct settings for your lens and camera body, you can use the same settings every time you do this type of photography.

Other Settings to Consider:

  • Obviously, use Manual Mode to control all the settings we’ve been talking about thus far so the camera doesn’t change them automatically.
  • Turn off Auto Focus OR use Back-Button Focusing, and make sure you don’t press the Back Button accidentally (more on focusing in a minute).
  • Set White Balance using the Kelvin setting. A setting around 5500 will give you the natural-looking black skies. I dial it down to 3500 because I like the cooler blue-looking night sky. In my opinion, it works better with the light pollution.
  • Turn these settings OFF:
    • High ISO Noise Reduction
    • Long Exposure Noise Reduction

Photo by Jamie Anderson

 

NOTE: The light meter in your camera is useless for this type of photography. You are overexposing a completely dark scene, so just rely on your manual settings.

FOCUS
You’ll also need to learn how to focus in the dark. Your autofocus will have a hard time focusing, but it may not be entirely useless. If there is a bright light in the distance, autofocus may actually be able to focus on it. In the scene above, there is a bright light on the horizon. This might actually be enough light for autofocus to work. You can autofocus on any bright light as long as it’s a long distance away, and your stars will also be in focus.

What if you want to make sure the objects in your foreground are in focus? In this situation, create some distance between your camera and the foreground object so both your foreground and the stars in the background will be in focus. As a general rule, stand at a minimum of one foot per focal distance from the nearest foreground object that you want in focus. So, if you are shooting at 24mm, stand at least 24 feet away from the foreground object. If shooting at 14mm, stand at least 14 feet away. One method for focusing on the foreground object (with autofocus) is to have someone stand parallel to the object and shine a flashlight back to your camera. You can then focus on the flashlight, which is the same distance away from the foreground object.

The best method for focusing goes like this:

  1. Put your camera in live view, then zoom in 10x.
  2. Shine a bright flashlight on the foreground object.
  3. In live view (zoomed in 10x), use manual focus and focus on the area where you are pointing the flashlight.
  4. Take the camera out of live view and make sure your lens is on manual focus.

You may be surprised, but you can actually get the foreground tack-sharp using this method.

Like any photography skill, astrophotography takes some trial-and-error at first. Once you determine the proper settings for your camera and lens, then you can experiment with different locations and setups.

A word of caution: I do recommend having a buddy with you when you’re doing this type of photography, unless you are very familiar with the area and know that it’s safe.

I look forward to seeing your new astrophotography images! If you have any questions, I can be reached at: Jamie@CoastalGeorgiaPrints.com

 

Jamie Anderson is a native of Savannah, Georgia, and enjoys photographing the one hundred miles of barrier islands, inland waterways, and historic sites known as Coastal Georgia. He currently volunteers as the Coastal Chapter coordinator and is a member of both the Conservation and Communications committees.

FACEBOOK
1
^ BACK TO TOP ^