Focussing for Nightscape Images

One of the most difficult aspects of Nightscape Photography is finding Infinity focus. Many people are excited after a night out shooting the stars only to be disappointed when they see their images on the larger computer screen and discover they are out of focus.

This video addresses some of the areas we need to look at in our quest for finding Infinity Focus when out in the field. It's hard to say that a blanket approach works for everyone because their are quite a few factors that come into play when shooting. Different cameras and lenses can make the process easy or somewhat frustrating.

My desire is to help people understand some principles and theory behind what infinity focus actually is and then give some guidance as to the methods to achieve it with any camera and lens combination. We look at the tried and true Live View Focusing method and then explore a less well understood but equally effective process of finding accurate infinity focus using a Depth of Field Chart.

The two images below were shot on the same night. The one on the left was the traditional method of utilising the live view screen of the camera to zoom in and focus on the actual stars themselves. The picture on the right is taken by first establishing the infinity focus distance using a Depth of Field Chart, and then focusing on that point which was actually on the small cubby house about 10 meters away from the camera. You will see that both images look exactly the same and the stars of both are in accurate focus.

                                                       Nikon D750  Nikon 20mm f1.8   @ f2.8  20 second exposure iso2000