Focus to Infinite

Every photographer has struggled with infinite focus

Concept

When you are trying to focus in low light situations and when you are using a tripod, the camera’s auto-focus system is basically unusable. Therefore, you must switch to manual focus. Imagine a situation where you are trying to focus on stars in a night sky. The camera cannot auto-focus and if you look through the viewfinder and try to manually focus using your eye, it is impossible to get accurate results.

Good quality lenses have a focusing window that you can use to manually focus the camera to any distance including infinite.

Settings

There are several different setups that you will see on DSLR camera lenses. The most common is this first example. You should line up the middle of the infinite logo with the small line at the top middle of the lens.

The second common focus set-up is as follows.  In this setup (very common with CANON lenses) you must line the bottom leg of the L that is next to the infinity symbol with the small line on the top of the lens. NOTE: The focus ring will turn a bit further, but if you like the line up with the infinite symbol instead of the bottom of the L, you will be severely out of focus. 

Techniques

The focus ring is very sensitive to movement and even a small adjustment, in the neighborhood of 1mm will cause the photo to be out of focus. Throughout the process of shooting, stay in the habit of verifying that the focus ring is in the correct position.

NOTE: Test out the lens. The theory that the lens is in focus at infinite is a theory. With many lenses, this is the case, but in some cases, the actual infinite focus point is slightly askew. Take some test shots of the stars and verify which spot on the focus ring produces the sharpest image.