|
All images © Bob Atkins
This website is hosted by:
|
 Author
|
Topic: Is the AI Servo "Jumpy" on the 1D Mark IV (Read 7798 times)
|
427l
Newbie
Posts: 6
|
I am borrowing a 1D Mark IV from a friend in an effort to see if I really feel the AF (and other features) are worth the money. I am basically interested in whether or not the camera can focus on a moving animal , say its' face, and stay focused even while its moving (w/ 70-200mm 2.8 IS lens) I have the camera set on AI Servo, with AF expansion set to all 45 AF points active (C.FnIII-8=3), the tracking sensitivity to zero (C.FnIII-2=0), AI Servo 1/2nd img priority to AF priority / Tracking priority (C.FnIII-3=0), and AI Servo AF tracking method to Continuous (C.FnIII-4=1). The primary subject I was using was my golden retriever (golden color) dog in my backyard, green grass, bushes and some brown mulch on the ground. I select a focus point, say the center one, and place it on this face for a few moments prior to movement and push the shutter down 1/2 way for focus lock. Once the dog starts moving the focus point seems to struggle staying on his face and instead it seems to jump around to anything that has a lot of contrast to it, sometimes it focus on the ground , sometimes things behind him, sometimes it will bounce between his side or hind legs and then back to his face. Is this normal.... with a 200mm zoom at f/2.8 should I expect to keep a moving animals face in focus? I haven't actually looked on a monitor yet at the result but I'm wondering if you can give me a feel for whether I'm expecting to much from this camera or whether maybe I am doing something wrong with the settings?
What should I expect or what will give me the best results in this case?
Ben
|
|
|
|
|
Logged
|
|
|
|
|
|
|
KeithB
|
First off, the AF system does not see color, it does not use the sensor at all. I think you are asking too much of the AF. It should be able to track moving things, but that is more like tracking the whole dog, not just the face. Try zooming out and see if it works better.
|
|
|
|
|
Logged
|
|
|
|
|
Bob Atkins
|
I'd probably cut down on the number of AF zones in use. You shouldn't need all 45 of them. As I recall (I don't actually own a 1D MkIV) you can select a smaller grouping around a smaller area of the viewfinder.
|
|
|
|
|
Logged
|
|
|
|
427l
Newbie
Posts: 6
|
Bob, so basically you're saying just use a smaller grouping like the specific AF point I select with the "surrounding AF points" grouping and just concentrate on keeping that focus point on or close to the dogs face while he's running? Basically , since the camera doesn't see color its not going to track the dog as I maybe preiviously envisioned (which would have been pretty cool)?
Ben
|
|
|
|
|
Logged
|
|
|
|
|
Bob Atkins
|
Yes, that would be my suggestion. If you just focus on the dog, leave the camera fixed and count on all 45 AF zones tracking the dog as it moves across the frame the AF system is going to have problems, especially if the dog changes direction and/or speed.
The AF system is pretty smart and it will try to track an object moving across the frame (handing off AF between zones) , but it has limitations, especially if the object is small and moving in an erratic manner and it would likely to be even more limited if it's moving in and out of background objects or the background is at a similar distance as the subject.
If I was a wildlife shooter in that situation, I'd be doing my best to track the subject by hand, only depending on the AF system to switch AF zones if my tracking wasn't perfect
|
|
|
|
|
Logged
|
|
|
|
427l
Newbie
Posts: 6
|
That is totally clear, thank you. I'm glad I'm getting this chance to demo this equipment and understand the capability of the camera. This is stuff I just don't see much on forums. Do you know if Nikon's D3 is similar or might it be better/worse at tracking a subject as I've described.
|
|
|
|
|
Logged
|
|
|
|
|
|
|
|
|
 |
|
