gene_can_sing
11-12-2009, 05:21 PM
I was on the verge of buying a Canon EF 70-300 f4 to 5.6 zoom.
However, I just found out that it is non-parfocal, meaning it doesn't keep it's focus throughout the the zoom.
Sorry, I'm a bit of a newbie to this, but is this anything important? The reason I ask is because when shooting video of surfing (something I enjoy shooting), the surfer continuously moves towards or away from you. Which might cause issues with the non-parfocal lenses.
But since the people are so far out, the focus seems to be less important. If said person is 300 meters away, and proceeds to move to 100 meters away (Shot at f8 to f 11), would the focus be thrown off on a non-parfocal lens at that distance? Or is it only when the subject get close to very close that the focus goes out (with 10 meters or so)?
However, I just found out that it is non-parfocal, meaning it doesn't keep it's focus throughout the the zoom.
Sorry, I'm a bit of a newbie to this, but is this anything important? The reason I ask is because when shooting video of surfing (something I enjoy shooting), the surfer continuously moves towards or away from you. Which might cause issues with the non-parfocal lenses.
But since the people are so far out, the focus seems to be less important. If said person is 300 meters away, and proceeds to move to 100 meters away (Shot at f8 to f 11), would the focus be thrown off on a non-parfocal lens at that distance? Or is it only when the subject get close to very close that the focus goes out (with 10 meters or so)?