I've had my D700 for about 8 months now and I continue to be impressed by the capability of this superb camera. My previous camera was a D200, which I still use occasionally.
Most of my photography is landscapes, urban, travel - subjects are generally static or slow moving and I am happy with my autofocus technique in these situations. Where I find that the D700 is very different to the D200 is with moving objects. I think that I understand Dynamic-Area AF with Continuous Servo using 9 or 21 points (a1 and a2 set to Focus Priority) - my results are't always brilliant for moving objects but I get a good proportion of shots in focus (see attached cropped image) and things improve with practice (typically 200-300mm, f8-11, 1/400 or faster, VR on, handheld). I've also tried 51 Points (3D Tracking) with Continuous Servo for moving objects (e.g. neighbour's dog) on a few occasions but have so far found it impossible to use with success. With the shutter button held down halfway and me doing my best to follow the dog with the centre focus point the focus bracket jumps around the viewfinder seemingly randomly between the 51 focus points, on and off and back onto the dog and the resulting photos (CL Release Mode) seem hit and miss in terms of whether the camera has focussed on the dog or the lawn - what have I failed to grasp about this 51 Points 3D Tracking mode?
51-3d is the one mode where the camera will show you which focus point it is actually using. It works quite well when the subject is easily distinguished from the background, normally by color.
In the other dynamic modes (9, 21, 51) the camera is limited to the number of points you select but only shows the point in the center of the group as this this the one used to establish the focus lock.
The fewer points used, the fewer calculations and less decision making needs to be done by the camera.
Objects moving directly at or directly away from the camera are the hardest ones for the camera to track.
---------+---------+---------+---------+---------+ Joseph K Seattle, WA, USA
Thanks Joseph - I will practice some more with the 51-3D setting with different subjects and backgrounds. The key thing that I've picked up is the need for the subject to be easily distinguished from the background - with that in mind I'll see whether I can work out when the camera finds that easy (and of course difficult) and use the setting accordingly.
I shoot sports a lot, and my experience, anecdotal though it may be, is that 51-3D works best for things like swimming, where the the subject moves in a fairly uniform and predictable manner. It seems to struggle more when shooting sports like soccer and football, where speed and direction of travel often change rapidly.
Sat 06-Apr-13 10:27 AM | edited Sat 06-Apr-13 10:28 AM by hillsidekim
Would having the VR on hamper focusing? I know it takes a small amount of time for the lens to lock on the VR. Would that be enough time for the moving subject to become out of focus? Kim Western burbs of Chicago