By Frank Gallagher, NANPA Blog Coordinator
Landscape photographers often want to get the greatest possible depth of field in their photos. In other words, they want to make sure everything from near to far is in focus. To do that, several factors come into play: the distance to the nearest object, your choice of lens, of aperture, and of where you place your focus point. Of these, the most important might just be the last, and there are several methods that can help you determine exactly where to focus your camera. You might have thought that where you place your focus point would be pretty cut and dried, but there are several schools of thought on how to determine just where that should be. There are even different interpretations of what “infinity” means!
What is depth of field?
First, some basics. This term refers to the distance between the nearest and farthest objects that are “acceptably sharp” in an image. This distance will vary based on how far from the camera the nearest point that must appear sharp is, as well as the photographer’s choice of lens focal length, aperture, and focus point. (See F. M. Kearney’s articles for more on how aperture, shutter speed and focal length affect depth of field.) There is also a mathematical formula with which one can calculate depth of field and some apps that will do it for you.
A wide angle lens will have greater depth of field than a normal or telephoto lens at any given aperture. On any lens, the smaller the aperture, the greater the depth of field. So, for example, a 24mm lens at f/8 will have a much larger potential depth of field than a 70mm lens at f/8, assuming they’re both focused on the same point. Similarly, a 50mm lens will have a greater potential depth of field at f/11 than it will at f/2.8 assuming it is focused at the same point.
With enough experience, you get a sense of what your camera and lenses can do and set your focus points almost by instinct. But when you’re starting out, what’s the best and easiest technique to use?
So, where should I focus for maximum depth of field?
OK, I have my wide angle lens and my aperture is set to f/8. Now what? Here’s where it gets tricky.
Using the mathematical formula, you can calculate where to place your focal point to get the nearest object acceptably sharp and retain the greatest depth of field. This focus point is called the hyperfocal distance. You can use an app to figure out what the ideal hyperfocal distance is and then estimate where that might be in your scene, but that all takes time and, often, the light is changing too rapidly to make those adjustments, so some shortcut is needed.
An old rule of thumb was to focus 1/3 of the way into the scene. Pick an object that’s about a third of the way into the distance or about a third of the way up from the bottom of the frame. With a suitably wide angle lens and a small aperture, that often works just fine. And it has the advantage of being easy. You don’t need any calculations or apps. But it doesn’t always work.
Spencer Cox at PhotographyLife uses a different method, the double the distance shortcut. Take the distance to the nearest object you want to render sharp, double it, and place your focus point there. If a colorful rock is two feet away, double that distance and place your focus point at four feet. That will give you a foreground and background that are equally sharp.
Both of these methods make intuitive sense. The very closest bits of foreground and the most distant objects might be a bit soft, but the increasing sharpness as you enter the photo helps lead your eyes into the composition. And we typically perceive distant mountains as a bit soft because of atmospheric haze and other factors.
Then I ran into two videos with completely different takes on the subject.
Popular landscape photographer and YouTuber Thomas Heaton typically focuses on the farthest object he wants in focus. On a landscape shot, he might focus on a hill in the far distance, which is often at the infinity mark on his lens. In a video, he tested his infinity method against focusing at the hyperfocal distance and using the depth of field preview function on his camera. For him, focusing at infinity gave superior results. With a wide angle lens and an aperture of f/9 to f/16 he knows he will get everything from 10 or 12 feet to infinity in focus. If he has foreground objects that are closer to his camera, he’ll focus stack two or three images. When he’s using a telephoto lens, he’s usually far enough away that everything will be in focus regardless of where he focuses.
I checked the Depth of Field Table in PhotoPills. Focused at 500 feet (as far as the app goes) with a 24mm lens at f/11, I’d get everything from five feet six inches to infinity in acceptably sharp focus. With a 15mm lens, it’s everything from two feet nine inches to infinity. So, there’s something to his method. And it certainly is quick and easy to use in the field.
Then I ran into a video featuring Marcus MacAdam in which my very understanding of the word “infinity” was challenged. Rather than infinity defining some extreme distance from the camera, he describes it as “the point we reach where, when we focus on a subject, everything behind that subject is automatically in focus too, so it’s impossible to focus on an object at infinity and get any other object further away out of focus.”
MacAdam does a quick calculation. For a 24 mm lens, infinity starts at 24 meters (or about 24 yards) distance, while a 200 mm lens reaches infinity at 200 meters (or about 200 yards).
So, with a 24mm lens, in a scene where closest object is more than 24 meters (yards) away, everything will be in focus at any aperture—even f/2.8! That means you don’t need small apertures like f/11 or f/16 but can shoot the scene using the sweet spot of your lens (typically f5.6 or f8).
Well, most landscape photographers like interesting foregrounds that are a lot closer than 24 meters (24 yards or 72 feet). What then? Here’s where this gets practical. Instead of focusing 1/3 of the way into the frame, MacAdams focuses “1/3 of the way between the closest point we want to render sharp and where infinity starts, because only this will give us the maximum depth of field.” So, for a 16 mm lens, “infinity” begins at 16 meters (about 48 feet). With a foreground that’s two meters from the camera, he’d focus 1/3 of the way between two meters (six feet) and 16 meters (48 feet) or at about 14 feet. According to PhotoPills depth of field calculator, that gets everything sharp, even at f/2.8. Focusing 1/3 of the way into the entire scene would place the focus point much farther into the scene, which is unnecessary as everything beyond 48 feet will be in focus regardless.
So there you have it. Four different ways to figure out where to place your focus point to get maximum depth of field.
What’s your favorite technique for achieving maximum depth of field? If you have another way of doing it that works for you, tell us about it. Drop us a line at firstname.lastname@example.org and explain how you do it.
Frank Gallagher is a landscape and nature photographer based in the Washington, DC, area who specializes in providing a wide range of photography services to nonprofit organizations. He manages NANPA’s blog.