Understand the Multi-Cam 1000 Auto focus

Understanding the Nikon D200 Multi Cam 1000 AF Module

The Nikon D200 is proving to be one of the most popular digital SLR cameras ever produced by Nikon, and for good reason. Within the Nikon D200’s smaller-sized body lives the heart of a true professional camera. Since it contains most of the feature sets of Nikons costing thousands more, the Nikon D200 is a complex and effective image maker as long as you understand the technology that makes it work.

One of the more complex parts of a camera’s operating system is the Autofocus (AF) subsystem. The Multi-CAM 1000 AF system was released for the first time in the Nikon D200, so we’ll use that camera and its manual as the base for this article.

To really maximize the use of the Multi-CAM 1000, it’s important that new users spend some time with articles like these (and with the camera’s manual) until they have a good grasp of how the AF system works. The initial time spent studying will result in professional quality images later.

The Multi-CAM 1000 AF system is not that hard to understand so why not get your user’s manual, and your camera, and let’s go over the autofocus modes in detail.

What is Multi-CAM 1000 Autofocus?

It’s a significantly improved version of the Multi-CAM 900 autofocus module found in the Nikon D100, D70, and D50 digital SLR (DSLR) cameras. Where the Multi-CAM 900 was limited to Single Area, Dynamic Area, and Dynamic Area with Closest Subject Priority modes, the Multi-CAM 1000 adds another AF mode called Group Dynamic. This mode gives you finer control over things like sports photography, macro focusing, and selective area AF.

While the Multi-CAM 900 had five AF sensors, the Multi-CAM 1000 gives us 11. It is very similar to the 11-sensor arrangement in the flagship Nikon D2x Multi-CAM 2000 system. So, you can expect professional-level performance from Multi-CAM 1000 in the D200.

Why is it called Multi-CAM 1000? The number 1000 represents the approximate number of CCD contrast-sensing elements in the autofocus system. With so many elements, it will autofocus in low to high light levels and at high speeds.

A unique feature of the Multi-CAM 1000 in the Nikon D200 is the ability to combine the 11 sensors into a 7-AF areas wide-array arrangement. This gives you the ability to better follow moving subjects like flying birds, race cars, or airplanes. We’ll discuss the Focus Zone Selection (7-AF areas array) in a later section of this article.

Now, let’s consider the various parts of the Multi-CAM 1000 AF system, and how they work.

What is Focus Lock, and How Does it Work?

Let’s start our exploration by looking at some basic information.
One question often asked is, “What does it mean to lock focus?” That’s a great question since it involves how the camera decides when a picture can be taken, and what AF modes you’ll find most useful for your particular needs.

If a subject is moving, the camera will use two technologies to track it. They’re called Predictive Focus Tracking® and Focus Tracking with Lock-On®.

We’ll talk more about them in a later section.

Using these technologies, the camera detects that the subject is moving in the few milliseconds that autofocus is in action. According to whether it’s in “single-focus” AF-S mode (Single Servo AF) or “constant-focus” AF-C mode (Continuous Servo AF) two distinct events will occur.

Single Servo AF: In this case, the autofocus system sees subject movement and does not “lock” the focus until the subject stops moving. When the subject stops the focus “locks.” Once this lock takes place, the little round green light comes on in the viewfinder, and autofocus activity ceases. You must reactivate autofocus by lifting your finger and reapplying pressure. The focus is truly locked and will not try to follow your subject unless you refocus. To follow a moving subject requires you to tap the shutter button as the subject moves.

Continuous Servo AF: When using this mode the autofocus never “locks” at all. It does “lock on” to your subject though, and tracks it until you take a picture.

So, “Focus Lock” is simply the camera making a decision, based on the fact that it has acquired a subject and is ready for taking a picture.

Once the camera decides that it is ready, something else comes into play. It will capture images with two levels of focus accuracy, according to how you have the AF “priority” set in Custom Settings a1 and a2. The two priorities are “Focus” or “Release.” We’ll discuss these in the next section.

Release Priority vs. Focus Priority (Custom Settings a1 and a2)

Let’s consider a couple of very important custom settings that can affect how many images you get that are truly in sharp focus. They’re Custom Settings “a1” and “a2,” which sets the camera to either FOCUS PRIORITY or RELEASE PRIORITY. These apply to AF-C (Continuous Servo AF), and AF-S (Single Servo AF). AF-C uses custom setting a1, while AF-S uses a2.

Focus Priority simply means that your camera will refuse to take a picture until it can reasonably focus on something. Release Priority means that the camera will take a picture when you decide to take it, regardless if anything is "in focus" or not. (Read the last paragraph a few times for clarity until it sinks in.)

Now, you might ask yourself “why is there such a setting as Release Priority?” Well, many professional photographers are shooting high-speed events at high-frame rates, taking hundreds of images, using depth-of-field (or experience and luck) to compensate for less than accurate focus. They are in complete control of their camera’s systems relying on a huge amount of practice in getting the focus right where they want it to be.

So, clearly, there are valid reasons for certain photographers not to use Focus Priority. But, most of those same photographers do not let the shutter release button start the autofocus either, since the focus would change every time the shutter button is pressed. They set Custom Setting a6 so the autofocus does not even activate until the AF-ON button is pressed. (see manual page 151) They then use the AF-ON button for their autofocus, and the shutter button to take the picture. They separate the two functions instead of using the shutter button for both.

You need to ask yourself, “What type of a photographer am I?”

If you are a pro, shooting hundreds of pictures of fast race cars, focus priority may not be for you. But, for the average photographer taking photos of his kids running around the yard, a beautiful landscape, flying birds, or a bride tossing a bouquet, Focus Priority is the best choice. For most of us, it’s better to have the camera refuse to take the picture unless it is able to focus on your subject.

When shooting quickly, focus priority may cause your camera to skip a series of out-of-focus images. Focus Priority will slow down your camera’s frame rate so that it will not reach the maximum 5 frames per second. But, I have to ask, what is the point of 10 out-of-focus images and 5 in-focus images? Why waste the card space, and then have to weed through the slightly out-of-focus images?

In Figure 1 below are pictures of the series of menu screens used to set Release vs. Focus Priority.

For AF-C Mode using Custom Setting a1:

The factory default is for “FPS Rate” priority. Most of us will want to change that to “Focus” priority. (FPS = Frames Per Second)

“FPS rate” and “FPS rate + AF” are both forms of Release Priority, with “FPS rate + AF” giving “improved” autofocus while still allowing the image to be taken no matter what. For reliably sharp focus in AF-C mode, use Focus Priority. On this menu, it’s the bottom “Focus” selection.

Now, let’s turn our attention to AF-S mode and Custom Setting a2. We need to verify whether Focus or Release Priority is set. Examine Figure 2 for the correct sequence of menu items.

For AF-S Mode using Custom Setting a2:

In figure 2, your choices are “Focus” and “Release.” Since the factory default is Focus Priority, it may already be set to “Focus.” If not, then select Focus. Now, your D200 is set up to take an image ONLY if it can focus on your subject, no matter what AF mode you choose.

Predictive Focus Tracking …

This relies on a technology designed to help in instances when your subject is moving as you press the shutter button to actually take the picture. There’s a delay in the shutter actuation time of only a few milliseconds. This is a mere 50-millisecond delay which could tend to cause fast moving subjects to go out of focus by the time the shutter actually fires.

When you press the shutter button for autofocus the camera’s computer asks, “Is this subject moving?” Here’s what happens next:

Subject IS moving: Predictive Focus Tracking figures out how far the subject will move before the shutter fires. Once you’ve pressed the shutter button all the way down it moves the lens elements slightly to correspond to where the subject should be when the shutter fires a few milliseconds later. In other words, it focuses slightly in front of your subject so that the camera has time to move the mirror and get the shutter blades out of the way.

It takes 50 milliseconds for the camera to respond to pressing the shutter release. If you are shooting an Airshow, for instance, in 50 milliseconds a fast moving airplane can move enough to slightly change the focus area by the time the shutter opens.

If you press the shutter in one smooth motion all the way to shutter release, first autofocus occurs, then the mirror moves up and the shutter starts opening. That takes the previously mentioned 50 milliseconds. In the time it takes for the camera to respond to your shutter release press, the airplane has moved slightly, which just barely throws the autofocus off. The camera’s computer predicts where the airplane will be when the image is actually exposed, and adjusts the focus accordingly.

Think about this illustration: Let’s say you were playing a ball game and you threw the ball to a running player. You would have to throw the ball slightly in front of the receiving player so that the ball and he arrive in the same place at the same time.

Predictive Focus Tracking does that for you so that you don’t have to focus your camera in front of your subject and wait 50 milliseconds for it to arrive. That would be a bit hard to time!

AF-C (Continuous Servo AF Mode)

If you have Focus Priority set (custom settings a1 and a2), the image will be in focus, if you do not, it may not be.

Lens movement, especially with long lenses, can be interpreted by the camera as subject movement. Predictive Focus Tracking in this case is tracking your camera movement while simultaneously trying to track your subject. Attempting to handhold a long lens will drive your camera NUTS (as it will you) when you later view the shaky pictures. Use a vibration reduction (VR) lens or a tripod for best results.

Nikon says that there are special algorithms in Predictive Focus Tracking that notice sideways movement, realize that you are panning, and shut down Predictive Focus tracking. If the subject is moving toward or away from the camera, it will track focus while attempting to predict where the subject will be when the shutter is released. Predictive Focus Tracking is not activated by the D200 for sideways subject movement or panning.

Focus tracking with Lock-On® (custom setting a5) …

This technology is designed with a completely different purpose in mind. It’s a focus algorithm that allows your D200 to lock focus on a subject and ignore anything that comes between the camera and the subject for a period of time. It will “Lock On” and track where that subject is on the array of focus sensors.

AF-S and Single AF mode is not as accurate when using Focus Tracking with Lock-On since the D200 is using only one selected sensor.

The “Lock On” part will work with one sensor in use. But how will the “Focus Tracking” work since there is only one sensor in use?

Dynamic Area AF will give you more accurate tracking of moving subjects, since it uses an array of sensors. When you switch to AF-C mode, also get in the habit of switching to one of the Dynamic Area or Group Dynamic focusing modes.

Custom setting a5 (Lock On) has little to do with how well the Nikon D200 focuses. Instead, it is concerned with what it is focused on. Here are some good reasons to leave Custom Setting a5, “or Lock-On, enabled in your D200.

Dynamic Area AF with Closest Subject Priority with Lock-On disabled will instantly react to something coming between your subject and the camera. By enabling custom setting a5, the camera will ignore anything that briefly gets between you and your subjects. If you turn a5 off and use Closest Subject Priority, your camera will happily switch focus to a closer subject, even if it only appears in the frame for a moment.

A good example of this is when you are tracking a moving subject, and just as you are about to snap the picture a closer or brighter object enters the edge of the frame and is picked up by an outside sensor. The camera will instantly switch focus to the intruding subject. If you turn off Custom Setting a5 you’ll get a camera that doesn’t know how to keep its attention on the subject you are trying to photograph.

When using Dynamic Focus modes, I call turning off custom setting a5, “focus roulette!”

Custom Setting a5 also allows you to select the length of time that your camera will ignore an intruding object that blocks your subject. The a5 setting specifies the following:

Short (about 1 second)
Normal (about 2 seconds)
Long (about 3 seconds)

This allows you to fine tune how you want Focus Tracking with Lock On to work. It can ignore an intruding subject for a few seconds.

In testing the Nikon D200, with Lock On enabled, I was amused at how adamant it was about staying with the current subject. I’d focus on a map on the wall, and then cover the focusing sensor with the Nikon D200 manual. The Nikon D200 would quickly switch to another sensor that detected the map. When I covered the new sensor with the manual, it would pop to another sensor and keep the focus on the map. I could just hear the Nikon D200 muttering, “Hah, you can’t fool me, I can still see a little edge of that map there, so I’m not changing focus!”

Only when I stuck the Nikon D200 manual completely in front of the lens, covering all the sensors, did the Nikon D200 decide to start timing the “a5 Lock On” time-out. After a second or three the Nikon D200 would give up on the map and focus on the manual instead.

In fact, I think I could hear a tiny little voice saying, “Hmm, I can’t see the map because of that stupid manual in front of my lens. Okay, 1-second…still no map…2 seconds…no map yet…3 seconds…well, I guess the map’s gone, I’ll focus on the manual now.”

Try this yourself! It’s quite fun, and will teach you something about the power of your camera’s AF system. But, if you actually do hear voices - consult a doctor. (I did!)

Below is a series of Nikon D200 menu selections showing how to set up Custom Setting a5 and its “Lock On” time-out period.

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

(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

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.

Nikon D200 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.

Nikon D200 Group Dynamic AF Closest Subject Pattern 1

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.

Nikon D200 Group Dynamic AF Center Area Pattern 2

Pattern 2 has a little trick available. Notice in Figure 11 above how the center pattern is a horizontal line of three sensors. Well, you can simply press the middle of the thumb switch and it will switch to a vertical line. In Figure 12 below, you will see the two CENTER selections that you may switch between.

Nikon D200 Group Dynamic AF Closest Subject Pattern 2

In Figure 13 & 14 we see the same idea as in Figures 11 & 12, except that no particular sensor has the initial focus control.

You may also toggle between horizontal or vertical CENTERs with the thumb button center switch. See Figure 14.

This Group Dynamic AF mode may feel a bit overwhelming or confusing at first, since there are so many selections, toggles, and patterns. But, read it over several times, set the settings, and play with your camera. You’ll come to understand it very well with a bit of usage.

Group Dynamic AF is a very powerful group of functions. Use them well, and you’ll be rewarded with better images.

Nikon D200 Dynamic Area Autofocus with Closest Subject Priority

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.

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.

Now let’s move on to a new technology introduced by the Nikon D200, namely, Normal or Wide-Frame Focus Zone Selection.

Nikon D200 Custom Setting a3 – Focus Zone Selection

There is another custom setting in the Nikon D200 that let’s you change how your D200’s AF sensor system works. Custom Setting a3 modifies how Single or Dynamic autofocus works. Instead of the normal 11 AF sensors, this setting changes your AF system into a 7-AF areas wide-array.

Nikon D200 Custom Setting A5 – Lock On® – Should I Use It?

This is a technology that has a lot of misunderstanding surrounding it. Since it is designed to cause the autofocus to hesitate for a variable time period before seeking a new subject it may seem to make the camera seem sluggish to some users. But, this “sluggishness” is really a feature designed to keep you from losing your subject’s tracked focus.

Once the camera “Locks On” to a subject’s area of focus, it tries its best to stay with that subject, even if it loses the subject briefly. That keeps the lens from racking in and out, and searching for a new subject as soon as the previous subject is no longer under an AF sensor.

It also causes the camera to ignore other higher-contrast situations, or closer intruding subjects while it follows your original subject. You will have to judge the usefulness of this technology for yourself. I suggest that you go to some event you are familiar with and track moving objects with and without Lock On enabled. Your style of photography has a strong bearing on how you’ll use it, or whether you’ll use Focus Tracking with Lock On.

Suggested AF modes for Various Subject Types

For static subjects like nature shots, family, and slow moving wildlife try these settings:

For moving subjects like a flying bird, a race car or cycle, or even a bride and groom walking up the aisle, I would suggest the following:

For sports shooting where my human subject is moving around in a group of other humans:

For macro shooting of static subjects like flowers, trees, rocks, and such try these settings:

For fun shooting like a party where I don’t want to think about my camera’s settings, but want great pictures:

Conclusion

The Nikon D200® is a very flexible camera with four fairly easy to learn AF modes. Memorize the four AF switch settings on the back of your camera today.

Don’t limit yourself to the Single Area AF mode. The D200 is a very “intelligent” camera. Allow it to assist you by dynamically tracking your subject, keeping the focus locked on a subject, or taking over completely so you can have some fun.

With this article fresh on your mind, go out and shoot a few hundred images. Play with this flexible AF system, and you’ll soon find yourself really enjoying your new found mastery of it.

With the D200, Nikon has created a powerhouse of an image maker! Use it to the fullest by discovering all the AF modes.

Keep on capturing time…