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02-03-2012, 05:46 AM   #1
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Any new CDAF tech from ME-F to K-01 ???

the CDAF tech on market doesn't know which way the lens should go while off focus. i.e. requires a full cycle focusing from min distance to infinity(All compatitors and all DCs are doing that), this time is a huge drawback for using CDAF for a legacy lens. however, the DC lens and some "mirorless lens" are made with a small focus group that it could be cycled quickly.

However, I found that the CDAF on my ME-F camera(the first AF DSLR for pentax?) knows which way the lens should go with its CDAF(there are 2 green arrows that indicate direction, and a dot for focus-on). If this is happenning on K-01, it will be revolutionary. Is there any hand-on focus review on web?

Here are some time data that from my test, on how much time is needed for a lens travelling from min to inf: (with lens cap on, K10d body)

18-55L: 0.17s from inf to min, 0.35s stop before going back

55-300L: 0.76s from inf to min, 0.39s stop before going back

If the ME-F tech is applied, K-01 will be a killer on market, well, maybe without the chimney


Last edited by kales; 02-03-2012 at 05:52 AM.
02-03-2012, 05:51 AM   #2
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this is from ME-F manual, the CDAF is telling user the direction of focusing, with whatever lens attached.
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02-03-2012, 06:53 AM   #3
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Well, unfortunately, this is not possible, as the ME-F used a early variant of today's PDAF technology, mixed with CDAF...

The ME-F CDAF sensors were located at the same place our current PDAF modules are now : bottom of the mirrorbox, with a secondary mirror (mounted behind the semi-translucent main mirror) sending some of the image into it...

The reason why the ME-F was able to predict the focus direction was because the two CDAF sensors were located slightly in front and behind the theoretical film distance... Thus, the ME-F could know which way to go, the sensor having the more contrast simply indicated the direction...
Focus was deemed good when both sensors were reporting similar contrast...

Only way this could happen in a mirrorless would be by adding recessed photosites... Hummmm, maybe I should make some patents on this???
02-04-2012, 09:58 PM   #4
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At least Panasonic GH2 knows which way to go

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