In the beginning, in order to keep costs down, lenses on most simple cameras were not mechanically designed to allow shifting their points of focus from near to far. Instead they were set or "fixed" at a certain distance that would usually assure acceptably sharp focus from about six feet to infinity. Thus, they became known as FIXED-FOCUS lenses. (Don’t confuse this with the term "fixed focal-length lenes" which simply means the lens is not a zoom, and has nothing to do with focus.)

Fixed-focus lenses covered the normal range of snapshooting, but out-of-focus pictures would usually result if the camera was moved in too close to the subject. If head and shoulders shots were desired, accessory "portrait" lenses were usually available to slip over the regular lens. Millions of pictures were taken with fixed-focus lenses on simple cameras like Kodak Brownies and, since most were never enlarged greatly, the resulting prints were acceptably sharp.

Touching now on just a bit of theory, every lens produces a range of sharpness called depth of field (not depth of focus) that extends one third in front of the object focused on, and two thirds behind it. The extent of that range depends on the camera’s film (or digital camera’s CCD) size, the lens aperture being used, how close you are to the subject, and whether you’re shooting with a wide angle or telephoto lens. Terms like "hyperfocal distance" and "circles of confusion" also play a part in the focus equation and we may cover that at another time, but not now.

Sophisticated digital cameras allow to you rotate the lens so you can focus exactly on the part of the image you’ve chosen to be the sharpest. This is called MANUAL FOCUS and it allows you to get some nice special effects, like keeping your subject in focus while letting the background go soft (out-of-focus). You have to know something about lens apertures to do this "selective focusing" consistently well; the wider you open the lens, the narrower the depth of field becomes. To assure correct exposure when using larger lens apertures, faster shutter speeds are required which can usually be programmed automatically by the camera.

When AUTOFOCUS came along it was hailed as a great new photographic miracle. You just pointed the camera at the subject and, with a little whirring of a tiny servo motor, the lens focused itself. Of course the subject had to be more or less in the center of the picture or the lens might go haywire and focus on something else. But, by and large, it worked fine and if your subject was off-center, you could just point the camera at him or her, hold down the shutter release button halfway, and the focus would be locked in. You could then re-frame the shot with the subject off-center and it’d stay in focus. It still works that way with today’s digital cameras.

All this was pretty straightforward and you didn’t need an advanced degree to understand it until the hype hit, with terms like "FOCUS-FREE." It’s a deceptive description and purposely ambiguous. It’s supposed to fool you into thinking "autofocus" when, in actuality, it’s just good old fixed-focus. It means that you don’t have to focus but it doesn’t mean that the camera will do it for you.

Now we’ve come full circle back to manual focus but it sometimes has a different meaning in the photodigital world. As you’ll recall, manual focus usually means that you can focus the lens on anything from near to far and in-between. But now it can also refer to setting an autofocus camera to a few pre-selected distances, just like fixed-focus. Olympus calls it QUICK FOCUS and its D600L has two buttons that can be punched for instant electronic switching to different distance settings.

It’s an excellent feature, because when those settings are used, you can take pictures even if your camera’s autofocus is not locked in on the subject. Many digital cameras just won’t shoot if they can’t focus on something; fast-moving objects or very low-lit scenes usually give them fits. Manual (or quick) focus settings override that lock-out, and let you get the picture- and keep it in focus. Using quick focus also can speed up the time between pressing the shutter release and making the actual exposure because it eliminates the wait for the autofocus to lock on. When you take your finger off the quick-focus button, the camera reverts to normal operation.

Finally, some inexpensive digital cameras claim to have manual focus, but it’s not continuous. It usually means the lens can be set to three distances- very close, medium, and far, sometimes called macro, portrait, and landscape. Although this is supposed to be an improvement over fixed-focus, in some ways it’s not as good. Unless you remember to move the focus setting from where it was when you took your last picture, you can end up with badly out-of-focus images- which is exactly the opposite of what the manufacturer intended.

If this was a bit confusing, don’t fret. From my recent experiences, I can assure you that you now know more about focus specifications than most of the Sales, PR, and Ad people who sell and promote digital cameras.

© Arthur H. Bleich 1999, All rights reserved.