Hyperfocal image - Blockup Gorge

Hyper-focal focusing

A technique for maximising depth of field

Joe Cali

What is hyper-focal focussing?
Hyper focal focussing is a technique which yields the maximum depth of field for a given combination of f stop and lens focal length.

What is hyper-focal distance
It is a distance from your camera that you focus at to maximise the depth of field.

Why do I need it?
Old camera lenses with fixed focal length lenses had a scale for determining depth of field. Modern SLR cameras come equipped with zoom lenses and auto focussing. Because depth of field varies with focal length or more correctly image scale, manufacturers cannot put a simple scale on a zoom lens.

How do I find the hyper-focal distance?
It is a mathematical quantity that can be calculated from a formula. Failed maths? Relax. Tables for most common focal lengths and f-stops used on 35mm camera's are provided with this article.

How do I apply the hyper-focal distance?
Look up the table for your lens focal length and f-number used. Set your lens to focus at that distance. Everything from about half of that distance to infinity will be in focus. You must set the lens focus to the hyper focal distance setting manually.

Is it the same for digital and film cameras?
No it isn't. The hyperfocal distance calculation is based on factors relating to the size of the film or sensor, the amount of enlargement necessary to make a certain size enlargement.

What are the assumptions used in this article?
Two tables are printed at the end of the article. One assumes that 35mm film or full frame digital sensor 24x36mm is being used while the other assumes that a half frame digital sensor 15x23mm is being employed. Both tables assume that the end print is an 8x12 inch enlargement being inspected at arms length. These numbers also hold for a 16x24 inch image being observed from 1.6 metres away.

You may not be able to see this in your camera unless it has a depth of field preview. The easiest way to convince yourself is to try taking two similar images. Put your camera on a tripod. Compose an image low to the ground so that nearby foreground is visible from closer than one meter right out to the horizon. Use aperuture priority automatic or manual mode and manual focusing. Set the camera to f16 and the zoom to 28mm.

First exposure Set the focus to infinity.and take one shot   Second exposure Set the focus to 2m ( the hyper focal distance for a 28mm lens set to f16 )    Third exposure Focus on the nearby foreground (1 metre) with the lens on f16

When you get the three pictures back, you will see that the one taken at the hyper focal distance setting is in focus from 1m from the lens to infinity. The other will only be in focus from 2m from the lens to infinity. The pictures of Barn Bluff and Blockup Gorge were taken using this technique. I had very little light, no tripod and was forced to trade off, shutter speed and depth of field using hyper focal distance. The third photo will have the horizon slightly out of focus and all the foreground sharp. Is the horizon being out of focus in #3 as distracting as the out of foreground focus in picture #1. The answer invariably is "no." If in doubt when in the field, focus on the foreground and let the background fall out of focus and take the shot.

Barn Bluff : f 8 and be there! Using the HFD technique, I only needed to use an 18mm lens on f 8 to get everything in focus. This was the second day of an 85km walk through the Cradle Mountain and lake St Claire National Parks. A heavy tripod was not an option. Knowing that f 8 was adequate rather than stopping down to f 16 as a precaution, meant that I could hand hold the camera ousing an exposure of 1/30 second @ f 8 rather than ending up with a blurred image using 1/8second @ f 16.

Hyperfocal Distance table

This table below lists the hyper focal distance in metres for a given combinations of lens focal length and f stop, . Look across the table to the column that corresponds to the camera focal length. Look down the column until you get the number next to the f-stop being used. Set your lens focus to this distance and the aperture to the f-stop shown. The lens will be in focus from one half the hyperfocal distance to infinity.

For example :
A 35mm lens set to f 22 has a hyperfocal distance of 2.2 metres. Set your camera lens to the 2.2 metre focus mark, the camera will focus on objects anywhere from 1.1 metre all the way to the horizon.