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Old Jul 13, 2003, 3:39 AM   #1
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Default Shutter Lag

Gooday all. I'm after a digital camera for action/sports photos. I know shutter lag will be a problem with a digital camera, but I'm wondering how much of a problem. The 2 sports I'd being taking photos in are moutnain biking and windsurfing, whihc are obviously not as fast as say motor racing. Just wondering how the Olympus c740 would hold up in the AF continuous mode. I like the 10* zoom, that is my main attarction towards the C740 (and reasonably priced)
I think the biggest test for the AF Continuos mode would be when the subject is coming directly towards the camera, causing a change in focus fairly regularly. I use to have a film SLR, that easily kept up with the subject, continually re focusing. Would/can a digital such as the C740 do that ?


Bill A :twisted:
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Old Jul 14, 2003, 2:35 AM   #2
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The reason AF is slow with digicams is because they use Video AF. Basically what that means is that the camera knows that it's out of focus, but it can't tell how far, or which direction. So it goes in one direction until it's in focus or it reaches the limit in that direction. Then it goes in the other direction until it finds focus or it hits that limit. Continuous AF works by finding focus on the subject and then continuously racking focus in and out by a small amount. As the subject moves, the camera moves the center of focus with it. This minimizes AF lag but doesn't eliminate it. It can also lose track of the subject if it changes speed or direction. It also eats batteries since the AF motor is continuously thrashing back and forth around the focus point. With SLR's (Both digital and Film) they use phase detection. Which means it can tell how much it's out of focus, and which direction it needs to go to achieve focus. This also allows for predictive autofocus so the camera can focus on the point the subject will be by the time the shutter actually opens. There is a digicam that has something similar to phase detection autofocus but it only has a 3x zoom. It's the Minolta F-300.
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Old Jul 14, 2003, 5:41 AM   #3
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Here's how autofocus works:

If you're really series about high-speed photography, you may have to splurge for a dSLR with little shutter lag. As a C-700 user, I don't think you'll be happy with the C-740's focusing speed for that type of photography.

Although in another message here someone has mentioned that the Casio QV-R4 (according to them) has a .01 shutter lag (although they didn't say if that includes focusing, or if it's in a manual focusing mode). Here's the link:
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