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08-28-2018, 01:23 PM   #1
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SMC Pentax-D FA 50mm F2.8 Macro Focus Clamp

SMC Pentax-D FA 50mm F2.8 Macro

Purchased this lens used. It is in excellent or better condition overall but the Focus Clamp does not do anything. When you turn it on, the focus stays the same, that is there is no difference between on or off. The readout on the camera changes from AF to MF but that is the only difference. I thought this was a clamp to make the manual focus tighter and or stop the focus ring from moving. The Quick-shift and auto-focus works great.

Do I understand the correct way this Focus Clamp is designed to work? Otherwise this lens is great.

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Last edited by vestige2; 08-28-2018 at 10:25 PM.
08-28-2018, 01:25 PM - 1 Like   #2
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The focusing ring should become stiffer. If it doesn't, that would be a mechanical issue- but the focusing ring is fairly firm to begin with, so probably not a big deal if that turns out to be the case.

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08-28-2018, 01:51 PM   #3
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Thanks for the input. I only have three auto-focus lenses and two are macros. I have 14 manual-focus Pentax brand and 4 manual-focus non-Pentax brand making a total of 21 lenses. I have not had the auto-focus very long. I have been using manual-focus for decades and auto-focus is new to me. I was worried about the Quick-shift on both of my macros but it works great. I think I can live with this problem on the Focus Clamp.
08-29-2018, 08:01 AM   #4
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Sounds like your clamp still works as an AF/MF switch on the lens, which will allow you to use Catch in Focus as described here. It can be a handy option.

I agree with Adam that the focusing rings on the DFA50mm and DFA100mm macros are generally stiff enough that losing the ability to lock the focus is not a great loss. It should have been disclosed in the item listing though.

08-30-2018, 05:22 AM   #5
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Photos made yesterday with this lens. It works fine without Focus Clamp.

Photos made yesterday with this lens. It works fine without Focus Clamp.
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