Understanding Single and Dynamic Autofocus Settings in the Nikon D200

The Nikon D200 has an array of four different autofocus methods, and some differences in how they work between AF-S and AF-C modes.

In figure 3 we see an image of the AF Area Mode Selector switch on the back of the Nikon D200. We’ll discuss each of the four settings in enough detail that you’ll feel more comfortable using the modes fitting your style of photography.

Spend a little time testing each of these AF modes, and in no time, you’ll feel comfortable with each of them. Then, at a moment’s notice, you‘ll know just which mode will best serve your purpose.

Single Area Autofocus Area Autofocus

Most photographers are perfectly happy to use the simplest autofocus setting, “Single Area AF.” With this setting your camera locks on to slow moving and static subjects using a single focus area of the eleven available in the Nikon D200. Most others would use the center AF sensor, or toggle to other sensors, with the multi-selector thumb switch.

Others lock focus and then move the camera to the final composition before taking the picture. In figure 5 there’s a simplified example of a D200 focus screen with Single Area AF enabled, and the center AF sensor selected. The plus sign shows which sensor is in use, and the red bracket shows which sensor you have selected. Sometimes these are not the same (as we’ll soon see).

(Please Note: You will never actually see a “+” sign in your camera’s viewfinder. I, and Nikon’s manual writers, use the “+” sign to symbolize which sensor is actively seeking or focused on a subject, which could be a different sensor than the one you have selected and that lights up in red.)

The multi-selector thumb toggle switch allows you to select any of the 11 sensors seen in figure 5. This mode works best for relatively static subjects, like nature, family snapshots, and slow moving wildlife. The sensor in use will briefly light up in red when first selected.

Single Area AF is great for the majority of photographers, and is quite easy to understand and use.

Dynamic Area Autofocus

This “Dynamic” AF setting allows you to control the sensor focal point, like in Single Area AF, but gives you a margin of safety in case your subject moves out of range of the selected sensor. All the AF sensors are active, so the subject will be tracked by the other sensors as it moves across their areas.

In figure 7 is the simplified D200 screen to show how extensive the area of focus actually is.

Notice that all the 11 AF sensors are active and seeking a subject (see + signs). But, also notice how the center sensor is selected as symbolized by the red bracket in the middle. You can move the primary focus area around at will, like in Single Area AF, but remember that all the sensors are active in case of quick movements.

It is important that you leave custom setting a5 turned on with this mode; otherwise, any intruding subjects might get the camera’s attention. Remember, setting a5 controls Focus Tracking with Lock-On. If you were focused on a rabbit hopping along the ground, and a bright red bird landed behind him, the D200 might just decide it likes the bird better and switch focus. Lock-On (a5) prevents that from happening by forcing the D200 to track the subject you first focused on.

Since Dynamic Area AF is truly dynamic, it sees any high-contrast subject in any of the 11 focus areas as fair game for autofocusing upon, even though you have a different sensor selected with the thumb switch. It doesn’t matter if the new subject is in front of or behind the old subject. If it has more contrast, or is larger and brighter, the Nikon D200 will eagerly seek to change to that new subject. By leaving custom setting a5 set to ON, the Nikon D200 is much smarter and tracks your real subject until it leaves the frame, or you take the picture.

Group Dynamic AF Closest Subject Pattern 1

In Group Dynamic AF Closest Subject Pattern 1, the camera focuses on whatever is closest and/or brightest in the viewfinder. In figure 10 is a simplified series of D200 screens that represents the focus sensors in use in this mode. Notice that no one particular sensor has the initial focus:

Since the D200 is using Closest Subject Priority, the camera will select the brightest and closest subject it can detect. It uses the cross-shaped pattern above to do so, and then tracks the movement of the subject across the AF sensors. The camera makes the choice of which sensor to use, initially, and as the subject moves from AF sensor to sensor.

For more detailed information on how Closest Subject Priority works, please see the section entitled “Dynamic Area Autofocus with Closest Subject Priority” later in this article.

Group Dynamic Settings

With Group Dynamic AF, you’ll select the sensor you want to use and the D200 will use it as the primary focus sensor. This setting allows you to be very precise in using individual groups of AF sensors by using selectable “grouped sensor patterns.” It’s somewhat similar to Single Area AF, except that the immediately surrounding sensors are also active, in a cross-shape (see figure 9 below). This allows some erratic movement from your subject, as long as the movement is not too large.

This works a lot like Dynamic Area AF, except that the active sensors are in a movable cross shaped pattern, instead of all eleven being active at once. This mode is best for erratically moving subjects that do not move very far. Maybe you are shooting an ant crawling around on a flower. He keeps moving, but your camera is bolted down to the tripod. This allows the camera to keep close focus on a small area, while allowing the subject to move around within that area.

Many sports photographers also use this mode for sports shooting. It allows an area around the primary focus point to stay active, which helps track a moving person, but not all eleven AF sensors are in use which might tend to pull the autofocus to another unintended person moving nearby.

Center Area Pattern 1, in Figure 9, is only one selection of Custom Setting A4. Pattern 1 also has another mode called Closest Subject Priority, which we’ll consider in the next section.

Dynamic Area Autofocus with Closest Subject Priority

Remember how the Dynamic Area Focus works? If a bird landed BEHIND your rabbit, the D200 may decide it likes the bird better? Well, this version of Dynamic Area AF uses Close Focus Priority to ignore any objects or people behind your primary subjects.

You have NO control of what sensor is in use, but you will see an indication in the viewfinder screen of which sensor is in use. The D200 manual on page 54 states that you will NOT see a viewfinder indication of which sensor is in use. This is apparently a misprint in the manual, which I think is a close copy of the Nikon D2x manual. In testing the Nikon D200, the Dynamic Area modes, including this one, all show which sensor is in use. The Nikon D2x does not show you which sensor is in use while using it in AF-C mode, while is does in AF-S mode. I’m glad to see that the D200 always shows the active sensor.

In Dynamic Area with Closest Subject Priority, there is no indication of which AF sensor is in use UNTIL you start the AF by pressing the shutter button half way. But, then, you will see a red sensor flash showing which AF sensor is focusing on your subject. You cannot control that sensor in this mode, though.

The camera focuses on whatever is closest and/or brightest in the viewfinder. In figure 16 at right is a simplified Nikon D200 screen that represents the focus sensors in use in this mode. Notice that no one particular sensor has the initial focus:

This mode is great for snapshooting, or for group shots, or any time you don’t want to make any focusing decisions, yet still want great pictures. One of my favorite reasons for using it is the old two person background gap problem we discussed before. How many of us have beautiful pictures of the background, while the two people we wanted to take a picture of are completely out of focus? When you focused your camera, YOU were looking at the people, but the camera sees the gap between them, and a nice bright something in the background. Voila, ruined picture!

Close Focus Priority pretty much eliminates that problem, since the subjects are closer than the background. But, what happens when someone walks between you and your subjects? Do you want the camera to focus on the new closer subject? Not usually! So, it is also important that custom setting a5 is left ON with this AF mode. Focus Tracking with Lock-On prevents anything that might move in front of our “locked on” subject from interfering with our focus.

Please note, though, this warning from Nikon: “Camera may be unable to select focus area containing closest subject when telephoto lens is used or subject is poorly lit. Single-area AF is recommended in these cases.”

So, all you birders, wildlife shooters, and sports photographers out there take heed. It may NOT be a good idea to use Closest Focus Priority with your big telephoto lenses, unless the subject has very high contrast. Be forewarned! Why not try regular Dynamic Area AF instead.