Hyperfocal Distance Guide
The concept of hyperfocal distance is easy to understand: focus a lens at the hyperfocal distance and everything in the photograph from some near distance to infinity will be sharp. Landscape photographs are often taken with the lens focused at the hyperfocal distance; near and distant objects are sharp in the photos.
Application of the concept leads to many questions: Which lenses are best for using hyperfocal distance focusing? What is the hyperfocal distance for a lens? How do I focus at the hyperfocal distance? Do I have to focus exactly at the hyperfocal distance? In this article we'll look at the basics of using hyperfocal distance to maximize depth of field in a photograph.
Hyperfocal Distance Definition
Choosing a Lens
Normal to wide-angle lenses (50mm and shorter lenses on 35mm cameras) are good candidates for hyperfocal distance focusing. These lenses have a relatively short hyperfocal distance when set to larger f-numbers. For example, the hyperfocal distance for a 28mm lens set to f/16 on a 35mm camera is about 5.5 feet. Everything from 2.75 feet to infinity will be sharp in a photograph taken with this lens focused at the hyperfocal distance.
Telephoto lenses are rarely used for hyperfocal distance focusing. The hyperfocal distance is quite distant with these lenses. For example, the hyperfocal distance for a 200mm lens set to f/16 on a 35mm camera is about 275 feet. Everything from about 138 feet to infinity will be sharp in a photograph taken with this lens focused at the hyperfocal distance. You can see that a 200mm lens isn't useful for taking a landscape photograph in which you want near objects to be sharp.
Calculating the Hyperfocal Distance
If you are fortunate enough to have a lens with a depth of field scale, you don't have to calculate the hyperfocal distance. Read the "Focusing on the Hyperfocal Distance" section below to learn how to use the scale.
You can calculate hyperfocal distance with the simple hyperfocal distance equation. It is a function of focal length, f-number, and circle of confusion (or, more precisely, the circle of least confusion.) However, you probably don't want to use the equation when you're out shooting. Instead, you can just use one of the many charts, tables of values, and software that are available. These tools will show the hyperfocal distance for a lens set to a particular f-number.
As stated above, hyperfocal distance is a function of the circle of confusion. You'll likely become bewildered by the many explanations for the circle of confusion. The debate over the "proper" circle of confusion has been raging for more than 70 years and will probably be raging forever.
Discussion of the circle of confusion is beyond the scope of this article. (See "Circle of Confusion" for an in-depth explanation.) However, I suggest that you use 0.030 mm for 35mm film. "Circles of Confusion for Digital Cameras" lists values for many cameras. This circle of confusion calculator is useful for calculating a value for other cameras.
Links to many sources are on the links page of this site. You can find dozens of charts, tables of values, and calculators on the internet by searching for "hyperfocal distance calculator" or "hyperfocal distance chart" on Google.Com.
The DOFMaster Hyperfocal Chart software for Windows operating systems prints hyperfocal distance charts.
The DOFMaster software for Windows operating systems emulates the depth of field scales that used to be engraved on lens barrels. It prints scales (circular slide rules) that you can take into the field. These scales provide a quick and easy way to find the hyperfocal distance for any lens and f-number combination.
The DOFMaster LE program for Palm devices is a easy-to-use program for calculating depth of field and hyperfocal distance in the field. This on-line depth of field calculator also calculates hyperfocal distance.
Focusing on the Hyperfocal Distance
You must focus the lens at the hyperfocal distance after deciding on a lens focal length and f-number combination that yields the hyperfocal distance you need. This is easy to do when the lens has a distance scale and a depth of field scale. But, many modern lenses don't have a distance scale and most don't have useful depth of field scales. Methods for focusing with these lenses are explained below.
It is important to note here that you should not change the focus after the lens has been focused at the hyperfocal distance. When you look though the viewfinder of an SLR camera you'll see that the near objects aren't sharp when the lenses is focused at the hyperfocal distance. The reason is that the lens aperture is wide-open. The depth of field you see in the viewfinder is not that same as that produced by the lens when it stops down to take the picture. You may be able to see what depth of field will be produced by the lens if your camera has depth of field preview.
It is common for beginners to adjust the focus to get near objects in focus when they look through the viewfinder. Have confidence that objects from half the hyperfocal distance to infinity will be acceptably sharp in the photographs and avoid the temptation to change the focus.
Three methods for focusing at the hyperfocal distance are explained below:
Measuring Hyperfocal Distance In the Field
You don't have to measure to the hyperfocal distance when your lens has a distance scale. As described above, you can just set the lens focus index opposite the distance on the scale. With other lenses you'll have to measure to the hyperfocal distance so you'll know where to focus. You can also just estimate the distance as described in the next section of this article.
Use of a tape measure is the only accurate way to measure to the hyperfocal distance from the camera position. As you usually won't have a tape measure in the field, you probably can't accurately measure the exact hyperfocal distance. Besides, hyperfocal distance calculated using formulas is just a reasonable estimate for real photographic lenses. The hyperfocal distance equation is derived from the "thin-lens" equation, which assumes a single-element lens with no thickness. It doesn't apply exactly to any real photographic lens.
You don't have to focus the lens exactly at the hyperfocal distance. Focus the lens as best you can, and focus it slightly beyond the hyperfocal distance if you are unsure of your estimating abilities. Say, for example, focus at about 15 feet when the hyperfocal distance is 12.2 feet. Then, stop down one stop (e.g., from f/11 to f/16) to get a little more depth of field. See "Estimating Hyperfocal Distance in the Field" below for more details.
Here are two ways to measure from the camera positon to the hyperfocal distance in the field:
Estimating Hyperfocal Distance in the Field
You can just estimate the measurement to the hyperfocal distance when your lens doesn't have a distance scale and you don't have a means of measuring to it. Fortunately, the hyperfocal distance is near the camera position for normal and wide-angle lenses. So, you should be able to estimate the distance with sufficient accuracy.
By using your knowledge of the length of many things, you can make some decent estimates of distance in the field. For example, I can estimate distances of about 25 feet and 40 feet with some accuracy because of my familiarity with the width and length of my house. My car is about 12 feet long, so I use that knowledge (e.g., "that's about a car length away") to estimate the focus distance.
Use your best estimate of where the hyperfocal distance is from the camera position and focus your lens there. Then, apply these rules to give yourself some leeway:
Let's see how these rules apply to focusing a lens for hyperfocal distance photographs.
Everything from at least one-half the focus distance to infinity will be in the depth of field when the lens is focused beyond the hyperfocal distance. The actual near limit of acceptable sharpness will be less than 1/2 the focus distance. Say, for example, the hyperfocal distance is 12.3 feet for f/8 and your lens' distance scale shows 7 and 15 feet. Focus the lens at 15 feet. Everything from at least 7.5 feet to infinity will be in the depth of field. Note that for this example you'll have given up, at most, 1.4 feet of the depth of field (15/2 - 12.3/2 = 1.4). Stop down one stop to f/11 to include the extra 1.4 feet in the depth of field.
It's better to focus beyond the hyperfocal distance than to focus in front of it when estimating the focus point. The far objects won't be sharp if you focus in front of the hyperfocal distance. Say you have a 35mm camera with a 50mm lens set to f/8. The hyperfocal distance for this example is 12.2 feet. Everything from at least 7.5 feet to infinity will be sharp when the focus point is 15 feet . The depth of field ranges from about 5.5 feet to 50 feet when the focus point is at 10 feet; objects beyond 50 feet won't be sharp.
Stop down one stop from the f-stop you used to calculate the hyperfocal distance. For example, focus at the hyperfocal distance for f/11 and set the lens f-stop to f/16. Stopping down brings the near distance of acceptable sharpness closer to the camera position. Stopping down will generally give enough extra depth of field to account for any focusing or estimating errors.
Using Hyperfocal Distance in the Field - An Example
Here's how I set the focus point for this photograph of Lake McDonald:
Lake McDonald, Glacier National Park
I didn't have a depth of field scale or hyperfocal distance table for the Canon G2 lens (zoomed to 8mm). However, I knew that at f/8 the hyperfocal distance was something less than 10 feet. So, I set the focus to 10 feet. By focusing beyond the hyperfocal distance I knew two things. First, the depth of field would extend to infinity. Second, everything beyond 1/2 the focus distance (everything beyond 5 feet in this case) would be sharp.
According to the depth of field scale for the G2 lens, the actual depth of field is 3 feet to infinity for the 8mm lens set to f/8 and focused at 10 feet. The hyperfocal distance is 4.5 feet. If I had focused at exactly the hyperfocal distance, the depth of field would have ranged from 2.25 feet to infinity. So, in actual practice I lost about 9 inches of foreground sharpness by focusing at 10 feet. Those 9 inches aren't even in the photograph.
Remember that hyperfocal distance is just a reasonable estimate for actual photographic lenses. Focus a little beyond the hyperfocal distance and you'll know that everything from at least 1/2 the focus distance to infinity will be acceptably sharp in the photo.
The answers to the questions posed in the introduction are: