Today’s Question: I had been told to focus one-third of the way into a scene to achieve maximum depth of field, and this seemed to work well. But I recently saw a video suggesting that this was a myth in photography. Can you confirm whether this really is a myth?
Tim’s Quick Answer: The “rule” of focusing one-third of the way into the scene you are photographing relates to the hyperfocal distance, and I would say that it isn’t exactly a myth, but it is often a bit misunderstood.
More Detail: The hyperfocal distance is the closest distance you can set your focus while still having the depth of field extend all the way to infinity. Making sure you are focusing at or beyond the hyperfocal distance can therefore help ensure maximum depth of field, which is a popular goal in landscape photography, for example.
When you do set your focus at or beyond the hyperfocal distance, your depth of field will extend from approximately half the distance between you and the focus point all the way to infinity. Because of this, many photographers have employed the rule of thumb to focus a third of the way into the scene. The idea is that doing so will generally cause the entire scene to be in focus, because the depth of field will extend from about halfway between you and the focus point and infinity.
However, this only actually works if your focus point is at or beyond the hyperfocal distance. In landscape photography this rule of thumb often works out well, because of the distances and camera gear involved. However, it won’t work for all scenes. Depending on your configuration, focusing one-third of the way into the scene won’t necessarily result in depth of field that extends all the way to infinity, for example.
As a more extreme example, let’s assume the scene you’re photographing is a small detail with a macro lens, where you’re focusing a few inches away from the subject. No matter where you set your focus, you will not achieve depth of field for the entire scene, and more than likely the depth of field will only be a fraction of an inch. Focusing one-third of the way into the scene won’t increase depth of field and will likely mean that what little depth of field you do have isn’t in the area of the scene you are most interested in having in focus.
I recommend the PhotoPills app for calculating depth of field and hyperfocal distance. My video training course can help you learn to make the most of this powerful app for iOS and Android smartphones and tablets, and is available on the GreyLearning website here: