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02-14-2013, 02:29 PM   #1
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SMC DFA 100f2.8 macro clamp

Can anyone tell me what the "clamp" switch is used for on the SMC DFA100mmf2.8 macro? I called Pentax usa and they were clueless. I think the person helping me was born after the lens was produced.

02-14-2013, 02:33 PM - 1 Like   #2
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Lol. The clamp adds a lot of friction to the focusing ring so that you can more finely control, the focus, and so that you don't accidentally change the focus setting. Never use it with AF enabled.

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02-14-2013, 08:59 PM   #3
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Adam is right, the clamp switch adds extra friction for manual focus, and stops it from creeping. I do notice that on my dfa50 and dfa100 it also turns off the camera AF.
03-03-2014, 03:47 PM   #4
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This is what manual says

Here is what is on user's manual. As everybody says is only for comfort when using manual focus

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