Hyperfocus

Photography & Video

February 7, 2009

285

February 7, 2009

Anyone interested in landscape photography should understand and use the technique called Hyperfocus.

So, what the heck is Hyperfocus? Hyperfocal focusing is based on the the fact that depth of field typically extends 2/3 behind the point focused on and 1/3 in front. If you focus on infinity, the depth of field behind is completely wasted. So, if you are taking landscape photographs & choose the horizon or anything that sets the lens at infinity as your focus, either manually or using autofocus, you are going to have more of the scenery close to the camera out of focus then you would if you used hyperfocus techniques.

How do you “Hyperfocus?” Well, it was easier back when manufacturers built scales into barrels of lenses. A hyperfocus scale is shown in the bottom of each of the two diagrams on the left. The center diamond indicated the actual focus of the lens. The scale shows what will be in acceptable focus at different f: stops. Note that as the lens is stopped down, the range of what is in focus increases. For example, when the lens is focused at infinity & the aperture set to f: 16 the acceptable focus will include everything from infinity to 5′. By using the scale built into the lens, the photographer can manually set the focus to 5′. By focusing at 5′ the scenery at infinity is still in focus, and we gain a couple of feet – the scale shows that we will have acceptable sharpness down to around 2.5′. The photographer gains 2.5′ of acceptable focus by using hyperfocus techniques.

Another method for showing hyperfocus scales is used with this 55mm macro lens. The different f: stops are different colors – etched into the lens barrel are color coded lines that give the same information as the scale shown above.

Again, this was fairly easy to do when hyperfocus scales was built into lenses. The problem now is that most manufacturers have been leaving the hyperfocus scales off lenses for years. In fact, because many modern lenses electronically set the aperture, there many lenses that have no f: stop ring built into the lens – the only way to select an aperture is with the camera.

With this new $1700.00 lens, the only information available on the lens itself is a difficult to read focus distance, and the focal length the photographer chose! Since the camera rather than the lens is used to set the aperture, the photographer can still see that information in the viewfinder, however there is no information for determining hyperfocus values. Unrelated to hyperfocus, because modern lenses may not have a manual iris ring, you cannot use them on older manual cameras.

One solution is to use a Hyperfocus Distance Table. As long as you know the focal length of the lens & the f: stop you have chosen, a table will show you the hyperfocus distance, the distance where everything between one half the set distance & infinity will be in acceptable focus. Although it is possible to build a table yourself, it is far easier & faster to use one already prepared for you. The Nikonians website is very useful for any photographer, although as is obvious by its name, is primarily designed for Nikon users. Among its pages is a good description of hyperfocus, along with a table covering many lens sizes. By the way, this page also explains the “Circle of Confusion” (COC), the term used to determine acceptable focus. There is a link on the page to a printable PDF version that extends to 1000mm lenses you can add to your camera bag. If you want specifics for Nikons & other cameras, including some point & shoot cameras, a calculator is available.

To use the table, set your camera on aperture priority or manual, and choose the f: stop you wish to use. Using the focal length of your lens (or the focal length you have chosen if using a zoom lens) manually focus the lens to the distance shown in the table. This is not as easy as it seems, since most manufacturers don’t have all that accurate focus scales built into their lenses, but get it as close as you can. I’d try a couple of exposures with slight shifts of focus to make up for the inaccuracy of the focus scale on the lens. If your camera supports “Live View”, use it & magnification to check for focus accuracy.

You can also use your camera’s depth of field preview to visually check what parts of the viewing area are in focus. While holding the preview button down, focus to infinity, then back off the focus until the near parts of the image are sharp. Check the most distance part of the image for focus. If it isn’t sharp, refocus to correct.

Although you may need to dig deep into your manual to find out how to manually focus your point & shoot camera, hyperfocus techniques can be used with any camera that can be manually focused.

If you want those wonderful landscapes that are sharp from the rocks a few feet (or even inches) in front of the camera all the way to the mountains in the background on the other side of a lake, hyperfocus techniques are what it takes.