USM Speed : LUSENET : Ask Bob : One Thread

I have seen some texts describing certain USM lenses with focussing speed of 0.4s, 0.7s, etc from infinity to minimum distance. Does anyone know if all Canon ring USM lenses work with the same speed? This is only a matter of interest. I have several ring USM lenses, but how do I get info on their AF speed?

-- Anthony Wong (, August 21, 2000


Seriously, the speed of USM (ring type) is sufficiently fast enough that I pretty much can't tell 0.4 to 0.7 of a second. Don't obesses too much about it Anthony. Happy Shooting.

-- Alex Yap (, September 22, 2000.

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