DSLR Camera Settings for Astrophotography

Currently I only use a DSLR (Digital Single Lens Reflex) camera for astrophotography.  There are other more specialist cameras that can be used, but these require a computer to control them and view their images. You can also use compact and bridge cameras as well as mobile 'phone cameras up to a point, but as I have no experience of any of these I cannot say anything about them.  There are however, many websites, Facebook groups and forums specifically aimed at these other types of camera.

I'm also currently only using my camera lenses rather than a telescope to take astro shots, although I do have a telescope and intend to at least try it at sometime in the future.  So this post is only about the camera settings which I use to get my shots with my prime and zoom lenses plus teleconverters.

The first thing to do is to make sure that the camera is set to take RAW images, rather than JPGs.  RAW images store all the data captured by the camera's sensor, whereas JPGs lose some of it by compressing the image to make it smaller in file size (not image size). JPGs are mainly used to put photos on the internet or to share shots by email and social media, where file size usually matters more than quality.  Some basic cameras and mobile phones only take JPG images.

The next thing is that your camera should be in fully manual mode.  If your camera doesn't have a manual mode, you may have a 'night sky' setting that you can try.  Manual mode means that you control the shutter speed, the aperture and the ISO rather than the camera. You should also turn off any vibration reduction technology your camera or lens has, such as VR or IS.

The camera always needs to be on a tripod or tracking mount and it's best to use an intervalometer, a remote shutter cable or at least some kind of exposure delay or self timer to avoid wobbling the camera by pressing the shutter button. The slightest movement will cause blur.

You need to learn how to use your camera and focus in the dark, so it's good to practice changing settings in the light! Your camera's LiveView screen should be turned on so that you can see the live image on the back of your camera rather than having to use the viewfinder which is very difficult in the dark. Zoom in to a star in LiveView and slowly roll the focus ring on the lens back and forth until the star eventually appears as just a small bright dot.  It doesn't have to be the star you're shooting at as the focus will be pretty much the same for any distant object.

Exposure settings are largely a matter of trial and error as what what works for one person in one situation doesn't work somewhere else.  However it is good to have some starting values to aim at. I mainly use the following ranges of settings, but I do also experiment with others from time to time. Please remember these are my settings for my camera and lenses - yours may be quite different.

Untracked and Unstacked Wide Shots - Constellations and the Milky Way

• Lens: 14-24mm zoom and 24-70mm zoom
• ISO range: 1600-3200 : Aperture range: f/2.8-f/4 : Shutter speed: 10-30 seconds
• Number of shots: 1

Tracked and Stacked Deep Sky Objects - Galaxies and Nebulae

• Lens: 500mm with 1.4x, 1.7x or 2x teleconverters
• ISO range: 800-1600 : Aperture range: f/8-f/11 : Shutter speed: 30, 60 or 90 seconds
• Number of shots: 20-30

Single shots of the Moon

• Lens: 500mm with 1.4x, 1.7x or 2x teleconverters
• ISO range: 100-200 : Aperture range: f8-f11 : Shutter speed: 1/80th -1/200th second
• Number of shots: 1

As I mentioned above, experimentation with these exposure ranges is vital because conditions vary each night. Always do some test shots and have a look at what you're getting, making the necessary adjustments after each shot before starting a long sequence of exposures.

There is no magic wand, you just have to get out there and try it.  Don't be disappointed if your first few nights produce nothing or little worth keeping, mine certainly did.  Perseverance is key - don't give up.