Photographing constellations is a great introduction to astrophotography and a fun way to start learning the night sky. All you need is a camera, a lens and a tripod to start with. Constellation photography in its simplest form, only requires placing the camera on a tripod, setting the camera on Manual mode and taking the picture using the camera timer or a remote control to avoid camera shake. Don’t forget to always shoot in RAW format (Nikon: NEF).
Hover over the image below to see the annotations.
So, what to shoot and how to find it? Nowadays there is a plethora of apps to use to help you navigate the stars, constellations and deep sky objects. The screenshot below is from a free software called Stellarium. There is an option to see the constellation names and lines and also a really handy tool (see upper right corner) that shows you your field of view in a variety of camera and lens combinations. For example, to shoot Ursa Major, including the landscape with a crop camera (Canon 60D, Nikon D5300 etc) you need a 20mm lens or wider.
The image below is a 20-second single exposure, ISO 1600, f/5.6 using a Nikon D600 camera and a Samyang 14mm lens on a tripod. (Yes, this is me inside the cave!). Note the Ursa Major constellation right above my head. This is a Full Frame camera and an ultra-wide lens. This combination allows me to include a large part of the sky and landscape in one shot.
The first image in this post is the Cassiopeia constellation. It is a stack of many images and it was taken with a Canon 6D camera and a Samyang 135mm lens. In deep sky astrophotography, we stack images to improve signal-to-noise ratio (less noisy images) and we use a star tracker (or Equatorial Mount) to compensate for the Earth’s rotation and be able to shoot long exposures. For more details about astrophotography using a tracker, you may have a look at my other post: Joe the Alien Astrophotographer.
When we just use a tripod, without a star tracker, we only have a specified amount of time before the stars in our photo start to look like lines due to the Earth’s rotation. A practical rule to remember is that when using a wide lens (for example 14mm) you can shoot around 20 to 30-second exposures before the star trail issue is too obvious. When using a 50mm lens you only have a few seconds. A more accurate way is to use the ‘500 Rule’ which is the following formula: (Exposure time = 500 / crop factor * focal length). Example with a Canon 700D camera (crop factor: 1.6) and an 18mm lens: Exposure time = 500 / 1.6 * 18 = 17 seconds.
Note: A more accurate formula for calculating the exposure times is NPF Rule, developed by Frédéric Michaud. For simple constellation and Milky Way photography though, the 500 rule is more than fine. Also, keep in mind that these ‘rules’ are not written in stone. A constellation or Milky Way photo will look great even if stars are not absolute pinpoints.
Equipment: Any DSLR or Mirrorless camera is fine but it helps to have a low-noise camera and a fast lens. Canon 60D and Canon 6D are solid cameras and provide excellent value for money.