-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Henry Posner
Sent: Wednesday, March 19, 2003 11:18 AM
To: [EMAIL PROTECTED]
Subject: EOS Re: Extenders again


At 01:51 PM 3/19/2003 +0100, you wrote:
>I currently have a 100-400L and a Canon 2x extender and was wondering if it
>was only canon extenders that you lost auto focus on, or all lenses slower
>than 2.8 regardless of the extender used.

The 100~400 is f/4.5-5.6. With a 2x teleconverter you have, effectively a
200~800 f/8-11. The EOS 3 AF functions at an effective max aperture of f/8,
but only the center AF point does. As far as I can recall all other AF
bodies lose reliable AF if the effective max aperture is below f/5.6.
-- -

regards,
Henry Posner
B&H Photo-Video, and Pro-Audio Inc.



Hi HP,

The EOS 1V based bodies will also retain AF operation down to f/8 using the
central AF point too.  But when used at f/8 the central AF point is only a
horizontal sensor not the high precision cross type.


Cheers/Chip



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