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      01-09-2013, 04:21 PM   #4036
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Drives: 2012 MB C300 4matic
Join Date: Jan 2009
Location: Foothills of Mt Level

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Here's what I've found after more testing. Using just the center AF point and trying to AF with the lens set at 300mm f5.6 (so 600mm f11 with the Kenko 2x TC), it would lock AF *if* the subject had high contrast. The first four images below show what I mean. All have definite contrasting edges. Then I switched to using all AF points and let the camera decide. I was able to lock onto anything regardless of contrast, although not always my exact intended focus point. For instance, in the pic of the window dormer on the brown roof, I was trying to get the dormer itself and the camera chose the higher contrast brown and white stripes of the building, so again, contrast plays a role. But in short, it will AF at f11 given enough contrast.

Of note here, none of these images is tack sharp, which is a consequence of using a 2x TC in general. They also have not been massaged in ACR or PS. Basically SOOC.


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