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10-08-2013, 03:59 PM   #16
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Here is another representation, from Pentax this time. Once you understand an AF "point" looks for contrast at any point along the vertical and horizonal lines of the active AF point then you can see the problem.

Last edited by twitch; 10-08-2013 at 04:04 PM.
10-08-2013, 04:11 PM   #17
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QuoteOriginally posted by kenyee Quote
the current AF points are huge and don't match the display in the viewfinder.
Most of us know how big they are - they aren't that misplaced in case of my bodies, but yes the size is correct.
QuoteOriginally posted by kenyee Quote
Someone a while back who had a lot of Pentax f/1.4 lenses said the AF system just wasn't accurate enough (he was a practicing pro who did a lot of narrow DOF natural light stuff, not Benjikan's studio stuff) couldn't lay the focus point on an eye in a portrait and expect focus exactly at that'd be FF/BF a bit instead. That pro switched over to Nikon and was a lot happier.
Focus precision with fast lenses has more to do with wider spaced pair of focus sensors than the size of the "point" itself. Pentax had f/5.6 sensors only (till SAFOX X), so it couldn't be really accurate here and to my understanding the longer f/5.6 sensors are, the more precise the AF system is.
QuoteOriginally posted by kenyee Quote
So it really depends on what you shoot and what lenses you have.
I use fast primes most of the time and yes I do quite a lot of shallow DOF stuff too.
10-09-2013, 09:00 AM   #18
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The AF sensor has nine vertical lines indicating nine columns of AF points, but only 7 columns of AF points actually exist. Could the two points outside the 5x5 grid be double-wide?


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