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10-15-2014, 03:44 AM   #1
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Focus clamp doesn't seem to do anything.

Hey everyone!

Last Friday I shot an FA 100mm f/2.8 macro at eBay for 300 EUR. The price seemed pretty good, especially since the seller claimed the lens is in near mint condition. This was to be my first macro lense ever. The little guy arrived yesterday, wonderfully packaged and appart from one really minor scratch on the bottom (probably caused by a grain of sand on the surface the lens was set upon at some time), I can see nothing that suggests the lens isn't new!

The only thing I find irritating is that I can't figure out what the clamp is supposed to do - or if it does anything at all for that matter. The wheel itself feels pretty loose (it's easy to turn), but it locks into place at each end when you turn it. I can't really say that the focus ring feels any tighter because of this.

Am I entirely missing the point here or does this mean there is a problem with my lense?

Best regards

10-15-2014, 05:59 AM   #2
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From the lens operating manual;

"In manual photography...or in any situation where the lens is pointing down, turn the clamp screw to the ON position. The rotation of the focussing ring becomes tighter, helping to prevent the rotation of the focussing ring due to the lenses own weight and to avoid any shift in focus. When shooting in the autofocus mode, turn the clamp to the OFF position. Activating the autofocus mode while the clamp screw is in the ON position slows down the focussing speed. For normal use, turn the clamp screw to the OFF position."
10-15-2014, 08:34 AM   #3
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I have that same lens and without knowing what it did at first, I didn't notice a difference with it on or off. After learning its purpose, I can say there is a slight difference in the resistance when focusing manually. I've just generally left it off.
10-15-2014, 12:25 PM   #4
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I have the D FA 50 Macro which also has a focus clamp. As gtcal pointed out it is supposed to add resistance to make manual focusing easier. On my lens the difference is very slight and I don't find that it really helps manual focusing all that much so I just leave it off.


10-15-2014, 08:31 PM   #5
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It was one of the down sides to the FA. The clamp became loose. It is a feature on most of the FA 100s. Mine does work, but feels loose. It's still a great lens.
10-16-2014, 02:40 PM   #6
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The clamp function is mentioned on the 50mm version of this lens but not on the 100mm one. (look here FA 50/2.8 Macro ) Both 50 and 100mm lenses are identical in this respect. So it is a known design fault.
I have the 50mm one which has the same problem, they all have.


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