----- Original Message ----- From: "Larry Cook"
Subject: AF Performance (Was: Re: Opinions about 80-200 f2.8 zooms)
So the answer is that the camera possess the algorithms for AF but the performance is based both on the algorithms and how responsive the lens mechanism is? If that is correct then a lens that seems to "hunt" more than another is not directly at fault? It is the camera algorithms not being able to adequately handle the responsiveness of the lens? Interesting. Of course you would still want to avoid such a lens because it is the system as a whole that is important and therefore an unresponsive lens that causes the camera to hunt is still a bad thing regardless of which component is actually "at fault".
Unresponsiveness or hunting can be induced by a variety of external factors that have nothing to do with the equipment, as well.
Trying to focus on a low contrast subject that gives the AF nothing to latch onto will cause hunting. Low light levels will cause hunting, and this problem will be exacerbated by a slower lens.
Some third party lenses won't work as well with some cameras as first party lenses.
Consumer market equipment may not be a responsive as pro market equipment.
It isn't possible to get a camera/lens combination that will perform 100% flawlessly 100% of the time.
I think it is a good idea to focus manually whenever auto focus isn't required. This way, you will have that skill in place for when you need it.
William Robb
