Tuesday, November 24, 2009

The Death of Predictive Auto Focus

Sony had it. They bought it from Minolta, who developed, as some might remember, the first Auto-focusing cameras. The Konica-Minolta 7D was a marvel. You could point it at an oncoming car, at speeds up to 180 KM/hour, and it would nail the focus. Not on the windshield, not on the rear of the car, but on the nose. The front bumper. On any point where those big sensors could find good contrast. It wasn't the fastest focusing camera, but for motion, it was amazing as it could calculate the speed an object was traveling, and adjust the AF to stay ahead of the object. It could even calculate whether the object was accelerating or decelerating! Nice, eh?

So how do the others I've tried stack up? Let's see:
Sigma SD-14- AF not fast enough, no predictive focusing.
Sony A700- AF is lightning quick-but no predictive focusing means that the front bumper is soft while the driver is sharp. Disappointing really, as they now own the patents to the predictive AF algorythyms.
Nikon D300- AF is even faster than the A700, especially with Hypersonic Focusing, or Wave Motor focusing, BUT... it doesn't predictive focus either. The noses of cars are still soft while the driver is sharp. For panned shots the focusing speed is amazing, but it cannot calculate speed and trajectory at all like the old KM 7D could.

I've not tried any of the Canon gear, but the photos I've seen posted online indicate that their AF system doesn't do predictive focusing either. With modern lenses reporting distance when focused to the body, it's not difficult to calculate how far a vehicle has traveled in a set amount of time.

Will Sony ever use this technology again? They'd earn my business if they did!

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