70-200 L question


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Zephirum

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Mar 29, 2004
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I just got a 2nd hand 70-200 L lens, however it doesn't come with the manual. I am wondering what is the switch on the lens "1.2m-inf" / "3m-inf" use for? How do I use it?
 

vector1

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Feb 3, 2007
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The different settings for the autofocus will constrain the range over which the lens tries to focus on. For example, 1.2m -inf will try to autofocus starting from 1.2m up to inf if it can't get a lock. This is useful in situations where you are far away from the subject (sports) and you know you aren't going to be closer than 3m. Thus if you set the AF range to 3m - inf, you can get a faster focusing speed as the lens does not have to "turn" too far to get the right focus, as opposed to 1.2m - inf.
 

Zephirum

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Mar 29, 2004
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Thanks vector1, so setting it to "3m-inf" will have faster focusing speed for normal use?
 

calebk

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Jul 25, 2006
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Clementi
Thanks vector1, so setting it to "3m-inf" will have faster focusing speed for normal use?
Not necessarily. In the event that your lens does hunt, if you set the limiter to 3m-∞, and your subject is more than 3m away, the lens will save time hunting. However, if your subjects are going to be closer than 3m, then there's no use limiting it.
 

vector1

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Quite true, it all depends on how you define "normal use"
 

Ang Moh

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Oct 5, 2005
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Thanks vector1, so setting it to "3m-inf" will have faster focusing speed for normal use?
Setting to 3m-inf will have faster focusing speed as long as you are more than 3 meters from your subject. If subject is closer, use 1.2m-inf. It's just a distance switch that avoids the lens trying to focus close up if you already know your subject is far away.
 

kongping

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Aug 14, 2006
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From a practical perspective, just set it @ 1.2m - infinity.

The lens focuses pretty fast so the benefits, if any, may be more than off-set by lost shots if the subject gets too close.
 

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