Manual Focus Is Not Your Enemy

Featured Image: © Karol Pietka. Taken with the Irix 15mm f/2.4

Suggesting manual focusing is a great way to end a conversation with many photographers these days. After all, they've made a substantial investment in lenses that work with the AF systems on their DSLR cameras. It speeds up their shots. It eliminates the need to adjust the diopter. I could name a dozen more reasons I've been given for letting the camera and lens handle the focusing, and to be fair, many of them make sense in the right situations.

There's another side to the argument, however. I will ask you to take a few minutes to consider some of the best reasons to use manual focus. I hope to give you a new perspective on the issue and some food for thought about broadening your photographic horizons (puns intended). Ready? Here we go:

Auto-focus systems can't think creatively.

One of the most common terms you'll hear in reference to AF technology is "intelligent". While that may be accurate in relation to technology, it's the creative mind behind the camera that should determine where the point of focus should be in a photo. By allowing all that sophisticated hardware to determine the focus setting, you're actually giving up some creative control.

AF Modes can cause focusing errors.

Most DSLRs have at least 2 Autofocus modes: a standard mode and a tracking mode. Each of these has a drawback:

• If your subject or the camera is moving, shooting in standard, or "One-shot" mode means that the optimum focusing distance can change in the time it takes for you to press the shutter release.
• If you're shooting in tracking, or "Servo" mode, any movement of the camera or something in the frame can cause the focus to shift when you don't want it to.

Using manual focus may take a bit more effort, but you won't blow the shot because the wrong AF mode was set.

Auto-focus will almost always focus in the wrong place when you're shooting through a window or similar transparent object. Shooting through something like a chain link fence will also fool AF mechanisms.

Autofocus is useless in many situations.

No matter how elaborate and expensive your gear is, there are many situations that are going to fool your AF system. Here are a few:

• Low light: Your camera needs light to focus.
• Low contrast: very low contrast scenes can make it hard for your AF to resolve a point.
• Distant objects: The farther away your focal point is, the harder it is to line up a focusing spot on the exact point.
• Shooting through objects: Auto-focus will almost always focus in the wrong place when you're shooting through a window or similar transparent object. Shooting through something like a chain link fence will also fool AF mechanisms.
• Repetitive shooting and time-lapse: When you're taking multiple exposures of the same scene or shooting time-lapse sequences, AF systems can shift the focus from shot to shot.

In these situations, you're much better off focusing manually.

Judging depth of field and hyperfocal distance is difficult.

Many auto-focus lenses don't have depth of field scales, and even if yours does, the tendency is to ignore it when you use AF. That means that you'll either set your aperture size by your best guess or by pressing your DOF preview button after focusing. Using the preview button darkens the viewfinder, isn't accurate and guesswork is, well, guessing.

When depth of field is important, you're much better off setting both your aperture and focus yourself, to yield the results you want. The scale on your lens is the best indicator of what to expect, assuming you have one. Good manual lenses incorporate a DOF scale that eliminates the guesswork. Irix still lenses even have a hyperfocal distance scale that's invaluable when you want to ensure maximum front-to-back sharpness at a given aperture setting.

If I can shoot with a pro-quality prime lens for less than a third of the price of an AF lens, I'm okay with turning a focus ring.

Autofocus lenses are expensive.

You may recall that in the first paragraph, I mentioned that photographers invest substantially in their AF lenses. That's actually one of the biggest drawbacks to auto-focus. Let's compare the pricing on a few high-end lenses with and without autofocus motors:

• Canon EF 14mm f/2.8L II USM: about $2,000. (AF pro-level)
• Nikon AF NIKKOR 14mm f/2.8D ED: about $1,800. (AF only works with some cameras)
• Irix 15mm f2.4 Blackstone: $649. (Manual focus, electronic aperture & metering)
• Irix 15mm f2.4 Firefly: $399. (Manual focus, electronic aperture & metering)