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Hyperfocal Distance

(© Ian Plant) Finding the hyperfocal distance for any given photo is one of the most vexing technical challenges facing photographers today. Without getting too technical, think of hyperfocal distance as the optimum focus point (combined with an optimum aperture) that will render everything in your photo—from the element in the scene that is closest to you, to the element in the scene that is farthest away from you—as acceptably sharp in focus.

Remember, by stopping down your lens to smaller apertures, you extend your depth-of-field beyond the focus point—much like ripples radiating from a small stone thrown in a pond. Hyperfocal distance tells you where to set your focus so that you may optimize your depth-of-field to extend over the critical elements of your scene. Using the stone analogy, if you throw your stone into the far edge of the pond, the ripples may dissipate before they reach your side of the shore; if you throw your stone close by, then the ripples may never reach the far side of the pond; if you want the ripples to reach all sides of the pond, you need to throw your stone somewhere in the middle. To add another element to the equation, if the pond is large enough, then a small stone might not have enough heft to create ripples big enough to reach the shore. The right combination of stone placement and stone size will ensure that the ripples reach all parts of the shore. Hyperfocal distance and depth-of-field work together in a similar fashion to produce a photograph that is sharp from near to far.

Confused? Just wait, it gets worse. For now, I’ll give your brain a break, and ground this discussion somewhere near the realm of reality. Hyperfocal distance is what allowed me to ensure that the flowers, mountain, and everything else in between in the image below were rendered sharp. Understanding how hyperfocal distance works is critical if you want to make sharp 24”x30” prints to proudly hang on your wall.

[To learn more information about how I made this image, please visit my daily photoblog.]

Okay, your break is over. For a brief moment I’m going to get technical, just to make a point. Part of the reason that hyperfocal distance is so vexing is that it is built on a subjective variable; that is, what level of sharpness is considered to be “acceptable.” The criterion for the desired acceptable sharpness is specified by an aptly-named variable known as the “circle of confusion limit,” which (according to Wikipedia) “is the largest acceptable spot size diameter that an infinitesimal point is allowed to spread out to on the imaging medium (film, digital sensor, etc.).” Yeah, I know—huh? Basically, this is a subjective evaluation, dependent on the size of the film or the sensor, that something is sharp or not.

It gets worse. Other variables in the equation can be the size of the print that you wish to make, and how far away someone will stand to view the print. At this point, if your brain hasn’t begun to throb slightly, don’t worry—it will get even worse very soon. I did warn you that this is vexing.

There are several ways to calculate hyperfocal distance, although none of them are simultaneously accurate and easy to implement in the field. I told you this gets worse.

First, you can rely on the depth-of-field scales on your lenses. Old-style fixed-focal length manual focus lenses have great depth-of-field scales that are both easy to use and reasonably accurate. Alas, such lenses aren’t in much use these days. Autofocus zoom lenses, which are all the rage, feature severely truncated depth-of-field scales that are all but useless. Good luck finding your hyperfocal distance and optimum aperture that way.

Second, you can use your depth-of-field preview button, which comes standard on most DSLRs. Your electronic camera and lenses keep the aperture wide open to make things easy to see when you are composing and focusing through your viewfinder, stopping the lens down to your chosen aperture only when you trigger the shutter. By using the depth-of-field preview button, you manually stop the lens down so that you may preview the effect your chosen aperture has on depth-of-field. In theory, this should allow you to tinker with focal point and f-stop until you find the right combination of hyperfocal distance and optimum aperture. In practice, when you stop down you significantly reduce the amount of light coming in through the viewfinder (which, by the way, is ridiculously tiny to begin with), making it effectively impossible to see just about anything.

Third, you can manually calculate hyperfocal distance and optimum aperture using complex equations and charts, some of which are available as smart phone apps. You’ll need some way of accurately determining your distance from various elements in the scene—tape measures and range finders might do the trick—but when conditions are changing fast, the last thing you want to be doing is taking a math quiz.

Fourth, you can rely on conventional wisdom “rules-of-thumb” regarding hyperfocal distance. My favorite (and I say this facetiously) is the “focus one-third of the way into the scene” rule. Although I sometimes tell people this one, I quickly point out that it is (a) technically inaccurate, and (b) utterly meaningless. For example, when working with a scene that stretches from three feet to the horizon, focusing “one-third of the way” into the scene is going to give you a fairly preposterous result; where, after all, is one-third of the way between three feet and infinity? When working with scenes that include both very close and very distant elements, your hyperfocal point might only be a few feet away, a far cry from the number you would get applying the “one-third” rule. Another rule-of-thumb that is reasonably accurate and marginally practical is as follows: determine your distance from the closest element in your scene, and then focus at a point that is twice that distance. Unfortunately, with both methods you are making estimates or carrying superfluous measuring devices, and neither of these two rules tells you anything about the optimum aperture needed to ensure sufficient depth-of-field.

The bottom line is that playing around with messy tables and measuring devices, both of which will slow you down considerably, aren’t very practical when working in the field and make you look like a total dork (if, indeed, it is possible to look even more dorky than you already do with your baggy equipment vests and knee pads—yes, I mean you). Truth be told, determining hyperfocal distance for a given scene is something that comes with experience, depends somewhat on the lens you are using and its optical qualities, and is unfortunately one of those “I know it when I see it” types of things. And don’t forget that subjective variable I mentioned in the beginning—depending on your intended use, how sharp is sharp enough? I’ve been shooting for almost two decades now, and through experience I’ve developed a fairly accurate intuitive sense for the optimum hyperfocal distance and aperture for a given scene and lens combination. I’ll be the first to admit, however, that it is very much a fly-by-the-seat-of-my-pants sort of thing. More often than not, when reacting to fast-changing situations and working a near-far scene with a wide-angle lens, I’ll simply focus at a point between 5 and 7 feet away and stop down to f/16. A bit sloppy perhaps, but it gets the job done when I don’t have enough time to think things through.

Are there any reasonably practical ways of determining hyperfocal distance and optimum aperture? Well, actually, there is one that in my opinion works very well—Live View on your camera. The ability to zoom in and pan around an image in Live View really helps when you are trying to find the correct hyperfocal point to balance focus between near and far elements in a scene. Some lucky Canon users can take this a step further: many Canon cameras allow the user to engage the depth-of-field preview button in Live View. When you press the depth-of-field preview button, the lens will be stopped down to your selected aperture, and the Live View image will get dark for a moment, but then (unlike with your tiny viewfinder) Live View will compensate and brighten the image (unless composing in relatively dark conditions). When using Live View in conjunction with the depth-of-field preview button, you can actually see how your chosen focal point and aperture affects apparent sharpness and depth-of-field throughout the image—at 100%—allowing you to make focus and aperture adjustments until you find the perfect combination.

If your camera doesn’t support using Live View in conjunction with your depth-of-field preview button, Live View can still assist you in finding the hyperfocal point. Here’s something you can do, which, although not entirely technically accurate, will get you in the ballpark just as well as (if not better than) most other methods. Here it goes: when in Live View, zoom in to 100%, and focus first on the object in the scene closest to you. Then pan to the object in the scene farthest from you, and focus there. Now, try to find a focus point right in the middle of these two—or, put another way, find a focus point that renders both the near and far objects equally out of focus. This will give you something that resembles the hyperfocal point. Now, you’ll still have to make an educated guess about how far you need to stop down to get sufficient depth-of-field from near-to-far. For many shots, f/11 might be sufficient; for scenes that go from very near to the horizon, for example, f/16 or f/22 may be necessary. When in doubt, stop down a little extra as insurance. Although lens diffraction might be an issue (see my previous post on this topic), it is less of a concern than having some critical element of your scene rendered out of focus.

Also, the instant playback feature of your DSLR, which allows you to review images on your camera’s LCD screen, is useful for ensuring that you have optimized your hyperfocal point and aperture, although it can be a bit on the tedious side. After making your best educated guess about hyperfocal distance and aperture, take the photo, and then review the image, zooming in to 100% to check your sharpness from near-to-far. Make any adjustments as necessary and start again.

When it comes to hyperfocal distance, it is no wonder that many workshop instructors simply give up and tell their students “f/22 and be there.” It can be an incredibly opaque concept for many people, and getting it 100% right is a bit of a quixotic endeavor. In my opinion, simply knowing that concepts such as hyperfocal distance and optimum aperture even exist is half the battle. Figuring out a method for roughly approximating either is good enough for most people, including seasoned pros. In other words, try your best to optimize focus and aperture, but don’t lose any sleep over it.

Good luck! You’re going to need it.

P.S. Don’t forget to check out my new line of Photoshop video turorials. They’re extremely helpful, and even better, really cheap.

To keep up with my blog entries on my personal photoblog and on this blog you can subscribe to my blog feed, or follow me on Twitter or Facebook.

Creative Vision eStore by Ian Plant