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 - 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.
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).
Thanks for this post. I've been having a lot of trouble with the tracking while trying to shoot some birds... the tracking was completely inaccurate...I'm not sure what that was due to. I'm now wondering if that's due to setting a4 being set to "Normal". I probably won't understand the point of only using the AF-button to focus until trying this setting in practice.
I didn't realize the focus tracking lock setting impacted focus speed. I figured it would track as normal in servo mode but when a subject moved into focus range at a much closer distance, it would react according to the setting. I leave it on normal because I don't want the sudden change in focus caused by an inadvertant subject I don't want captured.
I am also under the impression that the more AF points you enable, the slower the AF performance. For this reason, I stick to center or 9 pt. AF.
For rjk - focus tracking lock impacts accuracy. It can get fooled by the subject itself, or more commonly, if you change subjects. When switching between subjects I notice the delay so I keep it off.
I don't know if more focus points make AF slower. I can say that 51-point 3D focusing is very fast and accurate so I don't see a big downside in using it.
I agree with most of what you wrote with the exception of AF-C focus priority. I think, and this is also from my experience, that if you use slow focusing lenses or bodies Focus priority should be used if you want your subject in focus. But, if you use fast af lenses and/or bodies Release makes more sense. I've been using Release when shooting any sport with my 80-200 AFS and D300 and rarely have OOF shots--shooting 8FPS BTW. If I have OOF shots it's usually my error.
I appreciate you taking the time to write all that out, however!
Good thread. However, there seems to be a little confusion about the benefits and effects of the a4 setting (Focus tracking with lock-on). Here are a few comments of my own based on recent playing with a new D700 and also extensive use of the Canon 1-series cameras which have a similar feature:
1. It does not affect how quickly the camera calculates focus - it just affects how quickly it reacts to changes in the calculated focus distance. Note that the focus process is pretty much to find a target; determine required focus change from existing focus setting; initiate required focus change; let that change happen (the lens has to respond); repeat as required. The camera is fast enough to do many focus calculations before you even see the lens start to change focus.
2. It does not alter the speed with which the camera tries to attain initial focus when you first activate the AF, whether that is done by pressing the AF-On button or half-pressing the shutter button.
3. It does not alter the speed with which the camera reacts to continuous (relatively subtle) changes in required focus distance - just the way it reacts to significant, sudden changes in focus distance.
4. Significant, sudden changes in required focus distance arise in several ways:
4a. Something gets between you and the intended subject and is at a very different distance. This can for example be other sports players, or twigs in a tree in front of a bird, or when an approaching car drops below the crest of a hill, etc.
4b. You let the chosen AF sensor drift too far off target and, combined with the area focus setting, you ran out of lateral focus tracking capability (as distinct from the focus distance tracking capability that applies to every focus sensor, lateral focus tracking is the ability of the camera to use adjacent focus sensors to maintain focus on the intended subject when needed). The fewer sensors you let the camera use the less lateral tracking capability it has to offer and the more it relies on the accuracy of your own aiming and tracking ability.
4c. You decided to focus on something else at a different distance but did not let the camera know by first releasing the AF and then starting it again on the new subject
4d. The subject changed shape or colour or tone or contrast or angle and that confused the AF system. e.g. note the difference in the appearance of a bird as its wings flap. Large-winged birds such as eagles are far more visible from some angles that they are when viewed front-on. The same applies for aircraft but they are generally less agile than birds. I'm guessing too that a sports player with different colours on the front and back of his shirt could pose a similar problem to 51-point 3D tracking that utilises colour information.
wjlapier wrote:
I agree with most of what you wrote with the exception of AF-C focus priority. I think, and this is also from my experience, that if you use slow focusing lenses or bodies Focus priority should be used if you want your subject in focus. But, if you use fast af lenses and/or bodies Release makes more sense. I've been using Release when shooting any sport with my 80-200 AFS and D300 and rarely have OOF shots--shooting 8FPS BTW. If I have OOF shots it's usually my error.
If you want the maximum frame rate of perfectly in-focus shots then I suggest that you use focus priority. It might cause a part-frame delay but that can be better than missing a whole beat on a wasted frame. On the other hand, two factors work in favour of using release priority: One is that you'll get something while the action is happening and that may be better than missing out on what could be very brief action sequence. The other is that depth of field may overcome any slight focus error anyway, making a delay unnecessary.
Even slow focusing lenses can generally cope with progressive focus distance changes as a subject approaches you. They lose out when the approach rate is too fast or when you select a new subject. It depends what and how you shoot as to how well they cope but admittedly some are worse than others.
Thx alot Joe. It did confused me while I was purely reading the user manual. However, are all these settings only be active when the camera is in CF mode? Cuz mainly Im shooting portrait and mainly use SF mode. I do still having issues with slightly blur images even my object isn't moving at all. I m thinking maybe My hands are shaky while taking pictures.
I did a practice lastnight (indoor) using 1/60 f1.4 and auto ISO. I have to extremely get my breath hold and make sure that when I release the shutter my finger wasn't over press to shake the camera. It was extremely hard and I still have shaky images 3 out of 10.
Any idea or simply my hands are shaky nothing to do with the setting. I have my camera set to 51 points dynamic area focus. Does the setting matters for taking portrait? If it doesn't then that means that I simply need more practice for not to shake my image
What FL are you talking about HapZung? I personally use release priority and AF-ON only (just like the suggestion for D700) on my D2H and D1H. Works great. I'm also always in continuous focussing mode. No problems with static or dynamic subjects. Just be sure that it's not movement blur from lack of shutter. Eg for a 50mm FL, you should use at least 1/80, just in case.
I think it's your shaky hands. You should try test on tripod.
Joe, Thanks for the detailed explanation. Very helpful. Regarding the AF-on button: It seems to me that, if I have the shutter button pressed half-way it will produce less camera shake when I press it the rest of the way. Are you saying that pressing AF-on will keep it focusing between shots faster and better than I could do using the shutter-release button? Is that the benefit?
The benefit of having the shutter button NOT AF is that you are delinking the two. That way you can choose to focus and recompose w/o it refocussing when you hit the shutter.
I set it on tripod while taking this picture. I forgot whats the exact shutter speed for it (I've to check it when I got home tonight) But even so, I've taking almost 10 test shots until I get it extremely sharp in the reflection of myself.
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.
or simply my hands are shaky nothing to do with the setting. I have my camera set to 51 points dynamic area focus. Does the setting matters for taking portrait? If it doesn't then that means that I simply need more practice for not to shake my image 
