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A funny thing happened as photographic technology became better and better: lenses got smarter, but photographers?—not necessarily.
Yes, modern lenses are ultra-sharp and super-contrasty, they focus automatically, and undesirable artifacts like chromatic aberration and barrel distortion have improved. However, autofocus technology has brought three critical changes that serious photographers need to consider carefully when they choose their lenses, because they can be a hindrance to thoughtful photography if not used carefully.
Editor's Note: This is a guest blogpost by Brian Dilg of NYFA. For more educational resources, you can check out lots of their classes.
The first is electronic autofocus itself. When it works, it's fantastic. A little focus-zone box lights up, you can hear a beep if so you choose, and you’re reassured that your focus is razor sharp. I teach it in great depth; I make my students practice it on moving targets; and I use it myself—sometimes. So what are the caveats?
First of all, on a camera with a sensor large enough where depth of field becomes critical (i.e., not cell-phone cameras), matrix focusing makes absolutely no sense. “Here,” you say to your camera, “I don’t know what I want in focus. YOU decide!”
And how does the camera “decide” what should be in focus? Not based on content. Not based on the photographer’s idea. Not based on where your brain is concentrating its attention, thinking, “This—THIS is my subject.” It just looks for the highest-contrast edge. Try using autofocus on a white wall sometimes—total failure. Autofocus systems don’t truly understand focus; they understand contrast, and they maximize it by spinning the focus ring. And as we’ve all experienced, when a camera can’t find something to automatically focus on, most refuse to shoot at all. Moment gone.
I would never do that, you’re thinking. I choose my autofocus points manually! So do I. And in low-light situations, that autofocus system is a lifesaver. I trust it more than my weakening eyesight. But the fact is that it takes considerable practice to skillfully use manually-selected focus points with autofocus (much more so than using manual focus). More importantly, it takes precious time to use, during the very moment when you’re trying to capture an image—even for a practiced expert—and it can introduce as many problems as it solves.
Great moments often last only a split second. In that brief moment, a photographer has to make a handful of decisions so quickly, that there isn’t even time to be consciously aware of them: ISO, aperture, shutter speed, focal point, vantage point, composition, focal length, exposure, and most importantly, the precise moment of exposure.
In the meantime, while you’re fumbling to find the little button that moves the autofocus point around, that moment is passing—and life keeps moving. So that eyelash that you were planning to focus on? Already moved. Still moving. And the perfect spot for that eyelash in terms of composition is often not where an autofocus point is necessarily available.
You know the drill: squeeze—move the autofocus point—pan the camera to keep up with the moving subject—squeeze again—lock focus—recompose—hope the subject doesn’t move again—and finally, shoot. I teach my students to pre-visualize the image they’re going to make before they even raise their camera to their eye, and to already be half-squeezing the shutter and picking their autofocus zone as they’re bringing their camera up to their eye. Not easy, but worth the practice.
However, there is one very simple way to keep your focus responding in real time to a moving subject. It’s called manual focus. You can compose perfectly the first time while following focus, and shoot whenever you like.
And if you’re like most people these days, you don’t use it. You’re so conditioned to the reassuring beep of the autofocus that you don’t feel confident in your focus without it. And here’s a tip: 95% of people I’ve met have never bothered to set the viewfinder diopter to match their eyesight. So chances are, everything looks blurry through the viewfinder anyway. (Not to mention that you’re straining your eyesight.) Defocus your lens, set the diopter so the gridlines in the viewfinder are sharp, and check it every day! Your eyes change, and the diopter knob slips.
Also, your composition is very often compromised by the facts that autofocus zones do not reach anywhere near the edges of the frame, and that focusing and recomposing take time. Sometimes you shoot prematurely before you’ve composed properly, because the moment is about to be lost. Alternatively, you don’t use the whole frame. We see these problems every day in the images made by our students.
This is not a case against autofocus. It’s a tremendous tool, and like all tools, it is invaluable in certain situations. But it is not a panacea, and it is a mistake to just leave it on all the time, instead of picking the best method for the shooting conditions.
Ideally, lenses should work just as well in manual and autofocus modes. Unfortunately, everything about the design of autofocus lenses is optimized only for automatic mode. That has dictated two changes that have a major impact on how you can shoot: short focus rings, and few depth of field marks, if any at all.
Manufacturers are counting on you to use autofocus. They sell far more cameras to amateurs than pros, and amateurs want automatic, easy everything, so autofocus is here to stay.
And they know you want it fast, or you’ll miss the shot. So they’ve made focus rings ultra-short. Short rings mean faster autofocus performance (the ring doesn’t have so far to spin), but it makes manual focus nearly impossible. The control is simply not fine enough.
There are exceptions, like the Canon ƒ1.2 prime lenses, or strictly manual-focus lenses like those made by Zeiss or Schneider—at a cost. If you want any chance of successfully using manual-focus mode, you need to pay attention to the length of those focus rings when you choose a lens. Like Little Red Riding Hood, not too long, not too short. Test before you buy.
What are they? Ask a photojournalist, who may quote you an old adage: ‘f8 and Be There.’ In other words, have your camera ready to shoot, use a reasonably deep ƒ-stop, and pre-set your focal point so that everything within your usual shooting distance (let’s say 1m – 4m) is acceptably sharp—a fact that you can verify simply by looking at the depth of field marks on your lens, gauging the distance by eye (a skill every photographer should develop). Roughly speaking, about one-third of your total depth of field is on the near side of your focal point, about two-thirds on the far side. Depth-of-field marks tell you exactly where those points fall—if you have the marks.
These days, depth-of-field marks are almost non-existent. The focus barrels are so short that there simply isn’t room for more than one or two, if any. Bottom line? You don’t have to be a war photographer to be missing shots. Did you ever try using autofocus to keep up with kids or pets? That situation is tailor-made for working depth-of-field ranges. So again, when you choose a lens, look for these.
Photo by Brian Dilg
One more consideration: If you want to shoot video with that fancy DSLR that can produce such beautiful high-definition images with cinematic shallow depth of field, you can forget about autofocus. It is unusable in video—at the very least, you’ll see the camera hunting for focus, and worse, the exposure is often temporarily adjusted by the camera in order to enhance contrast for the sake of autofocus, destroying the shot.
An alternative that many people have embraced, particularly those who also shoot video, is to buy used lenses, those following older designs, or strictly manual focus lenses with long focus rings and depth of field marks for every ƒ-stop.
There is no formula for great photography. There are as many kinds of photos as there are ways of making them. The technical needs of someone who shoots landscapes on a tripod are very different from someone shooting documentary street photography. A mark of a master is the ability to switch instantly to the technique that’s most appropriate to the situation, and that just takes loads of practice.
Something to consider is that an awful lot of great photographs were made before autofocus and zoom lenses were invented. Great technology is wonderful, but better technology does not mean better photographs. Cameras are wonderful machines, but they have no idea how to take a good picture. That can only come from the vision of the photographer.
Disclaimer: The opinions expressed in this piece do not necessarily reflect the views of B&H Photo Video Pro Audio