I\'m hardly the expert on this topic so read at your own risk. I have used a number of bodies over the years (both Nikon and Canon) and have a fairly good grasp of how tracking AF works. I can say that the AF modes have become harder to figure out but the end result is worth the hassle.
So here\'s my take on using the D700.
Let\'s go through some of the key settings and then we\'ll cover how to combine the settings given the subject.
The first setting is not negotiable :tongue: - you must learn how to use the AF-ON button: a5 - AF Activation.
AF-ON is your friend. It unlinks focus from the shutter. It takes some getting used to but it\'s well worth the investment. Why? Your brain will start to separate focus from release too and know when you need to re-focus and when to just release the shutter. It\'s a higher level of control that leads to more in focus captures.
Next setting to consider is AF-C Priority Selction:
Pretty simple choice to understand. The main thrust of your decision should be around frames per second and rhythm. If you are shooting heavy action, the camera will slow down if the image is not in focus. This may through off your timing since you are expect to hear a consistent click-click-click. I personally don\'t mind if the camera stops firing to acquire good focus so I use the last choice: Focus.
Next setting is probably the most overlooked setting and may explain user frustration: a4 - Focus Tracking with Lock:
This setting controls the amount of time the camera waits before refocusing if the subject is out of focus. The default is Normal. So if you are shooting a football game with players passing in between you and the subject, this setting makes perfect sense. Remember most football action is moving across the frame so your subject shouldn\'t change distance from the camera rapidly. It\'s thus preferable to have the AF delay to keep focus at the subject distance rather than jump to the subject passing in between.
If, however, you are shooting a single subject with no objects passing between you, AND your subject is moving towards the camera (or rapidly changing distance to you), then this will feel like the camera is not working.
Why? As the subject moves closer/farther away the AF will delay, based on your setting (long/normal/short), before refocusing. You will think the AF is not tracking correctly. So I generally set this to \"Off\" unless I know there will be something between the subject and me.
It\'s important to remember that Priority Selection and Focus Tracking with Lock should be chosen in conjunction with AF-Area Mode and the subject you are shooting.
Next setting to cover is AF-Area Modes:
The choice here is all about the subject and shooting conditions.
Two key questions to consider:
1) Will you move the camera to follow the subject OR will the subject move within the frame?
Why? Think about it. It you place the subject in an area of the frame and keep it there by moving the camera, you can select a smaller AF-area mode since the subject isn\'t moving much within the frame.
In this case Single-Point AF or 9-Point Dynamic-Area AF are best. In these modes you\'re telling the camera to ignore the rest of the frame and just look for subject movement in either a single point or a 9-point cluster.
If, on the other hand, you expect your subject to move within the frame and not move the camera much to track this movement then you need to use a larger AF-area mode. Depending on the mode either you or the camera will decide whether to move tracking points across the entire frame.
In this case you should be looking at 21-Point Dynamic-Area AF, 51-Point Dynamic-Area-AF, or 51-point 3D Tracking.
21-Point or 51-point?
How quickly does the subject move around the frame and how much control do you want to follow it? In 21-Point mode once the subject leaves the 21-point cluster you must move the focus area to follow it, if you don\'t the image is out of focus. This mode works best if the subject is moving around a specific area of the frame (1/3 or smaller) but not moving around the entire frame.
If the subject is moving around the entire frame then 51-point is the best choice. 51-point will follow the subject anywhere in the frame as it moves off your initial focus point. This is intended for smooth movement (runner, race car, horse) and not erratic subject movement (tennis player, bird, child jumping around).
What about 51-point 3D Tracking?
51-point 3D tracking is a bit different from standard 51-point. When you press the shutter halfway the camera stores the color area surrounding the focus point. So this works best when the subject is a different color than the background (think brown bird against a blue sky). This color information makes for more accurate tracking of highly erratic subjects. So as long as the color difference is there, you have a shot at very good tracking.
What about Auto-Area AF?
I don\'t recommend using it. Really a point and shoot option where I just don\'t see the benefits. Probably more useful in single-servo AF where the subject is farther away so your not looking for \"critical focus\" since you have plenty DOF and you don\'t want to move the single focus point around much.
2) How will the subject move - towards/away from the camera or across the frame?
This is where refer back to a4 - Focus Tracking with Lock-On. The AF-Area Mode will be most successful when combined with the correct Focus Tracking delay.
Combining Settings Based on Subject and Conditions:
Scenario One: Subject is moving straight towards the camera with no risk of anything passing in between you and the subject.
Focus Tracking with Lock-On - OFF
Single-Point AF or 9-Point Dynamic-Area AF
Scenario Two: Football game shot from the sidelines so action traveling across the frame at a consistent pace. Other players may move between you and subject.
Focus Tracking with Lock-On - Normal or Long
21-Point or 51-Point Dynamic-Area-AF
Scenario Three: Your child playing in the yard erratically jumping around the frame.
Focus Tracking with Lock-On - OFF
51-Point 3D Tracking
As I said in the beginning, I\'m not an expert but I know what works for me. Hope this is helpful to those of you learning the complex but brilliant AF system in the D700 (and D3/D300 too).
Nov 08, 2008 at 07:06 PM
Previous versions of Joe Marques's message #6361531 « How to: Using the D700 AF-C Mode »
I have used a number of bodies over the years (both Nikon and Canon) and have a fairly good grasp of how tracking AF works. I can say that the AF modes have become harder to figure out but the end result is worth the hassle.
