Notes On Aperture & Hyperfocal Distance

by Anthony Morganti

When I started out in photography over thirty years ago and photographed landscapes wanting the entire scene in focus, I generally stopped my lens all the way down to the smallest aperture available and snapped away. Later I learned that this wasn’t always optimal because, at smaller apertures, an effect referred to as diffraction comes into play. The image effectively becomes distorted when the light moves through the smaller aperture.

Eventually I learned that as far as sharpness is concerned, a lens is at it’s sharpest 2-4 full stops closed down from wide open.

f-stop chart

 

Using the diagram above, if your lens’s maximum aperture is f/2.8, you can assume that it is at it’s sharpest between f/5.6 and f/11. It may not have as good a depth of field at let’s say, f/22 but it will be at its sharpest at its point of focus.

I’ve done test shots with all of my lenses and found all but one are at their sharpest at f/11. The lone exception is my 50mm f/1.8 that’s sharpest at f/8. I call this f/stop – the f/stop where my lens is at it’s sharpest, my lens’s sweet spot.

To test your lenses and find their sweet spot, use a tripod and frame a scene, bracket three shots with one being 2 stops closed from wide open, one 3 stops closed and the final shot 4 stops closed from wide open. Compensate the shutter speed appropriately so that each of the three shots are exposed identically. Next, examine them in Lightroom or any photo viewing utility that allows you to zoom in and carefully note which f/stop the image is at it’s sharpest. That is that specific lens’s sweet spot.

Hyperfocal Distance

Over the past few years there’s been a lot written about hyperfocal distance. In photography, focusing your camera at the hyperfocal distance ensures maximum sharpness from half this distance all the way to infinity.

What is that magical hyperfocal distance? Well, it depends on the focal length of the lens and the aperture being used. For years photographers carried hyperfocal charts in their camera bags to look up the distance they should focus on. Now, since the advent of smart phones, there are numerous apps that instantly calculate the hyperfocal distance when you dial in the lens focal length and aperture.

Focusing A Third Of The Way Into The Scene

Many photographers don’t want to carry charts or use a smartphone to calculate the hyperfocal distance. They prefer to focus a third of the way up into the scene. The logic is that half that distance back to the camera would be in focus and twice as far beyond that focal point would be in focus so if you focus a third of the way into the scene, most of the shot will be in focus.

What I Do

I don’t like either method. In my opinion, the best landscape photographs have something in them that the photographer wants the person looking at the photograph to notice and focus on. It could be a little red cabin on a lake, or perhaps a craggily piece of driftwood on a beach. That little red cabin and that craggily driftwood should have the best focus. A blind adherence to the hyperfocal distance or of focusing a third of a way up into a scene may cause a photographer to neglect the point of interest. Perhaps you’re photographing a scene with a finely detailed foreground and a soft distant background. Blindly utilizing the hyperfocal distance or focusing a third of the way up into the scene means that the most important part of the shot, the point you want people to notice, will be soft. What I do is dial in the f/stop of my lens’s sweet spot and focus on most important item in the scene.

Lifeguard Stand

Click on the image to enlarge

In this photo, I wanted the lifeguard stand to be in perfect focus, I carefully focused on the stand at f/11 – my lens’s sweet spot. As you can see, the stand in the midground is in sharp focus while the sand in the foreground is nicely focused. In this shot I used a 10-stop ND filter to get a long 20 second shutter speed because I wanted the water to be smoothed out and the clouds blurred. Despite that fact, you can see that the water and the clouds are still in focus, their blur is just caused by the movement incurred over that 20 second exposure.

If I had used hyperfocal length, I would calculate it by using my lens’s focal length of 18mm and aperture of f/11. Using the app on my phone, I calculate the hyperfocal length to be 4 feet, 9 inches. The lifeguard stand was at least three times that distance so, if i focused using the hyperfocal length, the most important element of my shot wouldn’t have been as sharp as I could make it.

If I utilized the other method and focused a third of the way up into the scene, I would have focused beyond the stand which means that again, the most important element of my scene wouldn’t have had the best focus.

 

Sand and grass

Click on image to enlarge

In this photo, I wanted the grasses in the foreground to be in sharp focus. I used my lens’s sweet spot and focused on the grasses. As you can see, the rest of the shot is nicely in focus as well.

 

Hyperfocal distance focusing and/or focusing a third of the way up into a scene are fine if there isn’t a distinctive focal point in the scene — perhaps you’re photographing the sand dunes in the White Sands National Monument in New Mexico. In that case, by all means focus a third of the way up into the sand dune or calculate and use the hyperfocal distance but, if you decide to have a person in the shot, dial in your lens’s sweet spot and focus on the person.

 

In summation, do some experimentation to discover the sweet spot of all your lenses and when you’re setting up a shot, don’t lose view of what the most important element is in the shot. Make sure it has the best focus.