4. Autofocus vs. Manual Focus
The majority of lenses being manufactured today are capable of being used in either autofocus or manual focus mode. Nikon does not currently make a single lens for its DSLR cameras that isn’t capable of both. To keep costs down and make camera bodies smaller, Nikon removed the autofocusing motor from many of their consumer-level camera bodies and instead put the focusing motor in the lenses. The lenses that have the built-in focusing motor have the designation AF-S, which stands for Auto Focus-Silent Wave Motor. Lenses that do not have this built-in motor cannot autofocus on the D3300 and D5300 camera bodies.
Many, but not all, of the Nikon lenses have a switch on the camera barrel that allows you to switch between manual focus and autofocus. This switch is labeled with M/A and M. In the M/A mode, the camera tries to autofocus as long as the camera is set to autofocus. In the M mode, you have to focus manually by turning the focusing ring no matter what focusing mode the camera is in. For autofocus to work, you have to make sure that both the lens and the camera are in autofocus mode.
Now, if you are a purist, you might be thinking, “Why would I ever want to shoot in autofocus mode?” To which my reply would be, “Why would you ever want to shoot solely in manual focus mode?” There is value in shooting in both modes, and knowing when to move to one or the other will help capture the image you want without undue frustration with your technology.
Autofocus is a fantastic innovation for camera technology—a paradigm shifter. It allows us to be efficient in shooting and more accurate in many cases. When subject matter is in motion, such as a running horse (Figure 1.8) or football player, autofocus is an innovation I do not like to go without. My “good” shot rate increases in circumstances where auto-focus can be used, as opposed to manually focusing on such subject matter.
Figure 1.8 Continuous auto-focus was necessary for me to capture this horse running fast and at an angle that closed the distance between us. Although possible, manually focusing this event would have presented a few more challenges and a lot more missed shots.
ISO 100 • 1/800 sec. • f/5.6 • 400mm
However, there are times when manual focus is indeed your best option. Autofocus in Nikon DSLRs works well when there is enough contrast (the difference between light tones) on or between subject matter that the camera is able to detect. There are times when subject matter lacks enough contrast for the autofocus to work properly, leaving you with a lens—and really a camera—searching for focus. Very low-light situations, such as nighttime landscapes, come to mind (Figure 1.9). In these instances, flicking the switch on the lens to manual focus puts you in full control of the lens’s focusing.
Figure 1.9 For a timed exposure of some adventurous photography students crossing the Llano River, I set my camera on a tripod and switched my lens to manual focus to maintain a steady shot and to keep the lens from “hunting” focus.
ISO 800 • 30 secs. • f/11 • 17mm
Shooting macro (extreme close-up) photography also benefits greatly from manual focus mode. There is nothing more frustrating to this nature photographer than trying to autofocus on the petals of a flower that is occasionally bumped by a soft breeze. Autofocus will continually search for something to focus on, even if the autofocus mode is turned to Single in the camera. This isn’t easy on the eyes.
You can also use autofocus and manual focus together to achieve a single image. When shooting landscapes for which you want maximum depth of field, it is often helpful to use autofocus to focus exactly one-third into the scene (more on hyperfocal distance in the next chapter) and then switch to manual to keep the same focal plane when recomposing the frame. I do this when I intend to set up for a while—such as capturing a really large thunderstorm or light painting a structure—and want to make multiple exposures without refocusing for each shot.
In the end, using autofocus or manual focus is based largely on user preference. I am in autofocus 90 percent of the time. Over time, I’ve become used to the different autofocus modes Nikon cameras allow the shooter to use, and I’m extremely comfortable in “AF.” However, if manual focus is the wheelhouse in which you find yourself, then use it!