Talk:Autofocus

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[edit] Number of Canon EOS 3 AF sensors

Canon EOS 3 has 45 AF points. 6 of them act as high precision cross-type AF sensor with f/2.8 or faster lens. Central point acts as high precision cross-type AF sensor with f/4 or faster lens.

Reference : http://www.bobatkins.com/photography/eosfaq/eos3af.html

I think that this means that Canon EOS 3 has

• 45 normal precision horizontal-line sensitive single-axis AF sensors (each AF sensor has 2 CMOS sensors)
• 7 high precision vertical-line sensitive single-axis AF sensors (each AF sensor has 2 CMOS sensors)

So, strictly speaking, we should say that "Canon EOS 3 has as many as 45 AF points" or "Canon EOS 3 has as many as 52 single-axis AF sensors".

What do you think? --shotgunlee 04:52, 9 December 2005 (UTC)

I think it has 45 Area-SIR points in total, arranged as follows:

• 38 are horizontal-only standard-precision sensors active for any lens faster than f/5.6
• 6 points come in cross-type configuration with additional vertical high-precision sensors active for f/2.8 lenses or faster, among the horizontal standard-presicion sensors
• the central point has a standard-precision horizontal sensor for lenses up to f/8, and features a higher-precision vertical sensor active for f/4 lenses or faster

However, it's only my guess and there could be additional horizontal high-precision CMOS sensors; it certainly does not indicate how many actual sensing devices each point employs. --Dmitry _{(talk •contibs )} 16:30, 31 August 2006 (UTC)