Camera settings differ quite a lot, depending on what you want to achieve. If you want to take a detailed shot of the Milky Way, you have to expose for much longer than you would have to for taking a quick snap of Ursa Major. 

Based on what you want to image, you have to determine what kind of equipment you need and how to set it up. Even the imaging location depends on the target.

The basic equipment you need includes the following:

• DSLR
• Wide-angle lens
• Sturdy tripod

 
If you want to take longer exposures, you have to add a star tracker to your list. As the earth rotates, it looks like the stars are wandering across the sky. A star tracker counteracts this rotation, basically tracking the stars, letting you expose for longer without the stars having trails. 

My current equipment:

• DSLR: Sony a6400
• Lens: Sigma 30mm f1.4
• Lens: Samyang 12mm f2.0
• Tripod: K&F Concept

For a beginner, setting up your camera for Night sky photography may be confusing and extremely different from daytime photography. You want to maximize the amount of light you collect, which is achieved by long exposure time, higher ISO and a low f-stop:

RAW:
You should always shoot RAW, as you will lose a lot of detail and depth if you shoot JPEG. 

F-stop:
Stop down your camera 1 or 2 steps from the lowest one, to still let in a lot of light but to also get a sharper image, as most lenses are not perfectly sharp at the lowest F-stop. (I stop my 30mm Sigma 1.4 lens down to F2.0 for example.)

Focus:
Use manual focus. Autofocus just doesn’t work with stars, so you have to focus yourself. You can use the zoom mode and the brightness boost of the preview in your DSLR to see the stars better.

Timed shutter:
Pressing the shutter on the camera body creates a lot of vibration and force. To avoid this, you should use timed shutter at 5-10 seconds. Alternatively, you can use a remote shutter control device plugged into your camera.

Exposure time:
The hardest of the settings to get right. If you expose for too long, you get trails on the stars. That’s why you have to calculate the maximum time by using the NPF-Rule:

N (aperture):               
The f-stop of your lens.

P (pixel pitch):
The size of a pixel of the sensor of your camera. You can find it doing  
a quick google search or inside the manual.

F (focal length):           
The focal length of your lens in mm.

How to calculate:

[ (35 * f-stop) + (30 * pixel pitch) ] / focal length = max. exposure time (sec)

This may look very confusing at first, but it’s actually pretty easy. You just use the numbers of your setup in the calculation and you get the max. exposure time you can use, without the stars getting streaks.

Example:            I’m using a Sony a6400 DSLR with a Sigma 30mm f1.4 lens.

                            A quick google search reveals the camera has a pixel pitch of 3.9.

                            The lens is stopped down to f2.0

                             [ (35 * 2) + (30 * 3.9) ] / 30 = 6.23        

According to this rule, the max. exposure time for me is about 6 seconds. 

The rule is not 100 % bullet proof, but a solid starting point. Just take some test shots and zoom in to see if there are noticeable trails or not. 

ISO: Should be set last, in a way that you collect enough light but don’t introduce too much noise. 1000-2000 is a good starting point. Don't be afraid to go a bit higher (like 6400), as modern cameras and software are pretty good at removing noise. If you have a lot of light pollution around you, ISO should stay lower, as the image will get washed out if it’s too bright.

If you learn these basic steps, you will be able to shoot your own Night Sky in no time. The next steps would be stacking multiple images, in order to get more detail and light, and adding tracking/guiding, so you can get longer exposures. 

Written by Johannes Möslein, 11. March 2024