The problem you will encounter is AF.
Not many lenses are parfocal - it the AF point remains static while you zoom.
As such your AF not only has to cope with subject movement but with the change in focus while zooming.
Puausable but not easy and definitly pushing AF to the limits
The problem you will encounter is AF.
Not many lenses are parfocal - it the AF point remains static while you zoom.
As such your AF not only has to cope with subject movement but with the change in focus while zooming.
Puausable but not easy and definitly pushing AF to the limits
I was assuming the shot would be at a very high aperture so that the subject moved within the DoF range during the shot, and hence the AF wasn't an issue
But certainly one to take into account as RTS says
its something we do all the time in the bike game
ive never had a problem with my set up
usually a 1Ds body and 70-200 IS f2.8 seems to cope very well
with most jobs i throw at it
I was doing it yesterday at Silverstone, Canon 40D with 100-400L. I was picking up the cars heading towards me at 400mm, then zooming back to 100mm when they got close. The push-pull action of that lens makes it a bit easier I think.
Servo AF tracked them very well - better than I expected tbh. Drive was on high - 6.5fps. And yes, I ended up with masses of frigging photos! Still editing them now, as obviously 95% are rubbish. But most are decently framed and well focused I used centre-point AF, but others use multi-point. Depends on the subject I guess.
L lenses are better at this sort of thing, and pro spec cameras like the 1D or Nikon D3 do it really well. But the 450D has Servo AF doesn't it? Why not try it by pointing it up the road when a car is coming towards you and see how it does.
Whatever the result, servo AF will get you a lot more sharp photos that trying to do it manually.
I was thinking about this very thing the other day....I had a practice when my little boy was on the swings at the local park. Not that easy if I'm honest, I pictured a great image however none turned out how I envisaged.
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