 Steve Beckle |
Does Autofocus Follow Moving Subjects? My next camera will be an autofocus DSLR, which is new territory for me. When it comes to autofocus lenses, will the lens refocus continuously as the subject moves closer/further? I ask because my Olympus digital camera locks its focus and then doesn't compensate if the subject changes distance, i.e. you have to refocus. This is unacceptable for action shots, hence my question. Thanks in advance.
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Sharon Day |
Congrats on your upcoming purchase! An autofocus lens will focus continuously as long as you select continuous focusing with your camera in the menu. This isn't something the lens just does, it has to be selected in the menus. I have a Nikon D70 and I can choose for it to continuously focus or focus just once, then lock. I'm sure they all work the same way but I don't know firsthand.
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Jon Close |
Choice of autofocus modes is one of the many advantages of SLR over compact point & shoots. Nikon, Olympus, and Pentax DSLRs have choice of S (single servo locks focus) and C (continuous) autofocus modes. Canon calls their AF modes One-Shot (locks focus) and AI Servo (continuous autofocus).
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Pete H |
Hello Steve; First things first. Continuous focus is just as Sharon said, the camera will (attempt) to maintain focus as the subject changes in distance. "Predictive" focus is the camera attempting to (predict) where the subject will be if the subject moves as you are squeezing off the shot. The two are NOT the same. Predictive focus utilizes "zone" focus points of your sensor. Depending on the manufacturer, there can be a few to many focus points. With that said; all cameras in their focus abilities are not created equal. Personally, I despise continuous focus; here's why...The camera in continuous focus will shoot with no regard to weather the subject is in focus or not! Generally speaking, and I do not speak for all, most photogs will lock their focus to the center of the frame. No big deal here as one can simply focus, lock, recompose and shoot. There is also a "closest subject" mode on many DSLR's, where the camera will only focus on the closest subject..I guess that's how it got it's name. LOL Your best bet is to do what many have done...practice with it. See how well and how fast it locks up. One final thought: Metering as you pan etc will change..(i.e) Following a bird in flight as it approaches you may change lighting as it flies from sky to foliage in the background..Be aware and be prepared. The DSLR is a great tool, just as the hammer is; but if you don't know how to swing it, you will get disappointing results and "miss" often. :) I intentionally did not mention brand names when it comes to focus speed and accuracy; for that I know would start a little flame war..Read some reviews on the cameras and it will soon become apparent, all cameras are NOT created equal in regard to the question you pose. All the best, Pete
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anonymous A. |
In addition to the two modes Pete referred to, Canon (and perhaps others) offer a mode that locks on as abut then adjusts if the locked subject moves. This overcomes most of the problems that Pete referred to when using a Continuous Focus mode. It is also normal to take your exposure reading from the focal point...not all cameras allow you to do this, but it is especially useful with moving subjects.
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