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10-28-2012, 03:52 AM - 2 Likes   #1
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AF Speed and accuracy - precision in wording

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Last edited by beholder3; 08-11-2013 at 06:34 AM. Reason: [deleted]
10-28-2012, 04:10 AM   #2
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Good thread. But I think one also has to mention the "definition of AF." One of the quoted articles already mentions this. Pentax has wide AF points and it has its own idea on what the subject should be. This is why Pentax AF often appears to fail. But actually it is only misunderstood and then delivers the "wrong" focus. However, AF points probably have to be big, since Pentax has more cross-type AF points, but fewer total number of AF points. Either way, people often whine about AF, when its actually just this, and this is also happening with the Canikon flagships to some extent (as the quote in OP says)
So bottom line is.. don't put too much faith in tests. Instead, go and use the equipment, learn to use it best. And if it absolutely doesn't jive with you, try a different lens, a different body, or even a different brand.
10-28-2012, 05:34 AM   #3
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Good information - it should probably graduate to the 'Articles' section one day.

The other AF performance variable worth mentioning and which has been well examined by others like Falconeye is not just the brightness of the light, but how the AF deals with the quality of the light in a scene.

Specifically I'm thinking about issues of (a) colour temperature (eg tungsten under low-light causing problems) and the perhaps related issue of (b) chromatic aberration in the optics in the light path to the AF sensor causing AF sensor sensitivity problems.

Both of these issues have been addressed by Pentax now, via firmware in the K-5 and AF hardware improvements in the K-30 and K-5 II.
10-28-2012, 05:41 AM   #4
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Last edited by beholder3; 08-12-2013 at 01:38 AM.
10-28-2012, 06:08 AM   #5
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Last edited by beholder3; 08-12-2013 at 01:38 AM.
10-28-2012, 07:34 AM   #6
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QuoteOriginally posted by beholder3 Quote
Thats worth another thread.
Fair enough.

QuoteOriginally posted by beholder3 Quote
Also this needs to be adressed then in comparison.
True. Many camera brands have AF (and exposure metering too) issues with different colour temperatures, colour spectrum compositions, illumination frequencies (Hz), and lighting types (halogen, tungsten, LEDs especially). Etc. It is a big subject.
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