PDF on Infinity Focus for Star Trail and Night Photography

1. The Photographers Blog INFINITY FOCUS HOW TO FIND INFINITY FOCUS OF YOUR LENS? Infinity focus is mainly used to get distant objects in focus. During night photography or star trail photography, it is necessary to get the stars in focus. Let us understand what infinity focus is and how to get your lens to focus at infinity. What is infinity focus? Before getting into the real technical definition of infinity focus; let me try to simplify things for easy understanding. When you focus your lens on infinity, it means you have focused on things that are very far away from you. It also means that everything in your frame is in focus up to infinity. Infinity focus is mostly used for star trail photography or Astrophotography or most commonly while photographing the Milky Way With infinity focus, you make sure that the faraway subjects are in focus and will thereby appear sharp in your pictures. Technically, at infinity focus, the light rays coming from your subject are parallel to your lenses. Until the point of infinity focus, light rays tend to diverge or spread while they reach your lens. When you set infinity focus, you make those light rays parallel by virtue of your lens adjustment feature, so that once they are parallel, anything beyond the point of your subject remains in focus until infinity. Theoretically, everything remains in focus and that is why we call it as ‘Infinity Focus’. You don’t have to adjust the focus of your lens every time you compose for a picture.

2. The Photographers Blog When to use infinity focus? Infinity focus is typical to focus on far away subjects like stars, Milky Way or Astrophotography, where you want to make sure the subject appears sharp in your photographs. Shooting star trails is the best example for using infinity focus. Instead of relying on autofocus, you will get better results with manually focusing on infinity for far away subjects. Photographing Fireworks is another good time to use infinity focus. How to achieve infinity focus? Good old days manual lenses had hard mechanical stops on focus scales of the lenses. So it was easy to set the lens on infinity focus even in the dark by just turning the lens to a mechanical stop. With the advent of autofocus lenses, these infinity stops started to disappear. Setting up an infinity stop to a lens needs a lot of calibration for the lens manufacturer. With autofocus though it is possible to shoot at infinity, (later on that) so none of the manufacturers cared about giving infinity stops to autofocus lenses back then. Two effective ways to set your lens to infinity focus: 1.When your lens has the infinity marking on it 2. When you do not have an infinity mark or your lens