The focusing sensor was squarely on the back of the bird but it's soft, while the branch that he's perched on is nice and sharp. Eight shots with the same framing produced the same results. I think this is proof positive that it needs to go back to Nikon for repair. I'm still unhappy with this camera.
It's a bit hard to tell from the Web-sized copy, but it looks like the bird's beak is in focus. The focus sensors are substantially larger than the rectangle shown in the viewfinder, and they tend to favor high-contrast parts of the image to focus on. So, I suspect the performance of the camera is within specifications and repair service will find nothing to repair.
With the D2X, it's difficult to autofocus on small objects because of the size of the AF sensors.
Of course, if the D2X had focused on the bird's back its head would be out of focus because the DOF is so small, so I'm not sure you would have been happy with the shot anyway.
>With the D2X, it's difficult to autofocus on small objects because of the size of the AF sensors.
Is this a design issue? What's the significance of designing an AF sensor that's larger than the rectangle shown in the VF? Other Nikon DLSR's do not have this issue. I have used my D2H and the focus is dead on as long as the point of focus is the same size or slightly larger than one of the AF rectangles.
The D2H also has sensors that are slightly larger than marked areas, as does the D2Hs. As you mention, it's not normally a problem.
Although I'd prefer that the viewfinder markings were more accurate, there's a benefit to these larger AF sensors. If you're using one of the dynamic focusing modes, the nearly constant sensor coverage across the frame allows the camera to hand-off moving subjects from sensor to sensor without losing lock. This is extraordinarily nice when you have a subject like a bird or mammal that's moving around the frame - it's quite remarkable to watch to happen. Additionally, the larger sensor area is more likely to stay locked-on if you have reasonably sized subjects. That's because there's a greater likelihood of it finding sufficient contrast within the sensor area.
One thing to watch is splitting an AF sensor area 50/50 with subjects at two distances, both of which have good contrast. I've found that in this scenario (not a good photographic one, usually), it's possible for the AF system to lock on a point halfway between the two.
As with a lot of things, once you understand that the sensors are slightly larger than the markings, it's easy to factor that in and get good results. Small, low-contrast subjects remain tough with any current AF system.
As Jon says, and has been discussed many times in this Forum, the AF sensor areas on the D2 series are pretty big, and certainly are larger than the marked brackets in the viewfinder. It sounds to me as though the sensor covered the bird and some of the surroundings, and the branch/sky edge or the beak/leaf edge provided much more contrast than the feather/leaf edge.
If you haven't read it already, the CAM2000 AF article by Digital Darrell is a great primer on how to get the best out of the D2X.
This is a classic example of how to confuse the AF sensor in your camera.
1) Subject is tiny relative to the sensor 2) Subject is low-contrast 3) Subject axis is oriented perpendicular (roughly) to the sensor plane
In cases like this, ANY AF module will be confused, and will tend to either a) lock-on to a higher-contrast object (like the branch) b) split the difference between the front and back of the perpendicular subject
Your AF module is not broken. You found a situation where AF is nearly always confused.
The above posts all pretty well identify the relevant issues, for me.
This hummingbird example appears to me a a simple depth of field issue, amplified due to the long lens, because the bird's body is on the same axis as the lens. Most everything perpendicular to that axis, and at that range, appears to be in focus.
You may be better served by taking test images of static objects in order to isolate possible subject movement from lens/camera performance.
Depth of field is approx 1 inch with a 200mm lens at 9 feet @ f4. However the hummer2.jpg image looks to me like subject movement since some parts are OK. Not being a hummingbird expert but don't they zap around at high speed ? I would be suprised that they then keep perfectly still on a twig to be photographed even at 1/640. Try bumping up the ISO and shutter speed and see if the double image (on it's tail and rear of wing) disappears. If it does but still looks soft you'll have to increase your aperature as well to get more than 1 inch d.o.f.
Remember, the twig it's on will be affected by the birds weight especially if it has just landed even if you can't see it at 9 feet away.
You'll see that with a 200mm lens at f/4 and 9 feet, the DOF is approximately 0.05 feet in front of and behind the plane of focus-- 1.2 inches.
I shoot birds all the time and the hardest thing to do is get the head in focus when the darn thing is parallel to the lens axis. Really hard to do! I use continuous servo AF, and continuous (high) advance rate. I shoot a burst and hope that at least one will have the head of the bird sharp.
This is not a criticism of your technique. You've found a challenging subject, that's all.
i have shot hummingbirds with 300 and 70-200vr with the DX and the low contrast/no contrast back is not a good focus target.... the depth of field is very shallow at 9 feet with or without high speed crop.any judgement of auto focus performance should not be made on such a very difficult to evaluate target such as a moving bird.... Good luck with your new camera and there definitely is a learning curve on using the different auto focus parameters.....Birds are a very tough subject oftentimes especially when three of them will fit in the palm of your hand.....i recently shot some sharply focused midges in flight that were 1/16th in long by using bursts at a known focusing distance with my 300mm f4............fisheye16
I am sure your D2X is just fine. Here's a hummingbird shot that I took with mine and a 200-400VR with 1.4TC. Focus was clearly on his beak. I blew the shot, though, because my SB-800 was filling too heavily. I needed to set it at -2/3 (maybe even more being that I was so close).
I've been experiencing a different problem. I shoot mostly on AF picking one of the eleven single focus points. Recently I noticed that some of the focus points were not yielding sharp pictures (with strobe on a tripod in a brightly lighted room). I did a test to attempt to isolate the problem and actually mapped the problem The top row of focus points + the ones on each end (Horz) don't seem to be functioning. I did a hard reset of the entire camera (the two green buttons) and have the most recent version of the firmware. Has anyone ver had or heard of this problem? I called Nikon support and they were useless!