Long Exposure Without a Tracking Mount

To Capture long exposures of the night sky normally we would use a star tracker or telescope mount which is a piece of equipment that compensates for the Earth’s rotation so you can take sharp long exposure photographs of the night sky.

Unfortunately, these can be quite expensive but you can still achieve great images without a telescope tracking mount.

Basically the wider the lens i.e (18mm) the longer you can expose without getting star trails.

Most astrophotographers often use what is called the “500 Rule”.

“The 500 Rule”

500 Divided By the Focal Length of Your Lens = The Longest Exposure (in Seconds) Before Stars Start to “Trail”

For example; let’s say you’re taking a shot with a 18mm wide angle lens. 500 / 18 = 27.77 seconds, which you can round to 27 seconds. So you can roughly expose for 18-27 secs depending on if your camera is full frame or crop sensor before the stars with begin to trail.

This image below of the Andromeda galaxy was a short 20 sec image, to achieve a better image with less noise and more details, we would normally take many images of the same shot and then ‘Stack’ the images which will produce a better image with more details and less noise. You can see the difference below with the 2 images, the top one was 1 image 20secs and the other was 45x 20 secs images stacked and then edited in Photoshop.

Night sky without a tracker

Andromeda Galaxy With a DSLR and Lens

Best Camera Settings For Night Sky Astrophotography

Here are the Best Camera Settings for Milky Way & Star Photography:

Camera Mode: Manual Mode – This mode allows you to independently and manually adjust the ISO, Aperture, and Exposure time by hand.

Image Format: RAW Image Format

Metering Mode: I find Matrix Metering on my Nikon  to work the best for night photography. Canon calls this same function Evaluative Metering.

I tried all the different metering modes my camera has to offer and Matrix seems to be the best. But maybe what works for me might not work for you , but try and experiment!

White / Color Balance: For all night photography adjusting your colour balance certainly helps.  I find myself shooting at 4200-4500K.

ISO: I would recommend trying iso 1600-2500 max and use widest aperture as your lens will allow F3.5 if you are using a kit lens on a Canon.

  • Long Exposure Noise Reduction Setting – Set to Off
  • High ISO Noise Reduction Setting – Set to Normal

Finally, set your lens to focus to infinity by turning the focus ring until you see the ∞ symbol.

You may need to adjust focus, to get pin point stars

I’ll try and cover image stacking in my next article on Taking Images Of The Night Sky Without A Tracking Mount.