[aoeu]

It just arrived in the mail. When the clamp knob is set to ON the focus ring is stiffer but not locked. AF still works.

The question is: Is that normal or should I send it back?

Peace?
aoeu

[TER-OR]

AFAIK, that's how it's supposed to work, slow the focus down a bit so you don't overshoot as easily.

[scratchpaddy]

AFAIK, that's how it's supposed to work, slow the focus down a bit so you don't overshoot as easily.

Exactly. I was confused about this at first, too, when I noticed it on my FA 100.

Autofocus lenses generally have very loose focus rings so that the autofocus motor doesn't have to work too hard. However, manual focusing is much easier and more precise if the focusing ring has more resistance. With the FA 100, you get the best of both worlds. It's a really well-designed lens, and the optics are superb. Happy shooting!

[aoeu]

Thank you for a quick helpful answer:




Second Light. The first was to distant to be interesting. No cropping.

[bdery]

slow the focus down a bit so you don't overshoot as easily.

That's not exactly its purpose. The clamp is there to make manual focus easier, with more feedback (instead of being "lifeless"). It's not a good idea to leave the clamp on when using AF since it adds friction which could, in theory, stress the AF mechanism.

[hyyz]

That's not exactly its purpose. The clamp is there to make manual focus easier, with more feedback (instead of being "lifeless"). It's not a good idea to leave the clamp on when using AF since it adds friction which could, in theory, stress the AF mechanism.

This is not its purpose either. The manual says below. I think the original purpose is to prevent focus shift during critical focusing.

Clamp Screw
FA Macro 50mm f/2.8 and 100mm f/2.8 lenses
are equipped with a clamp screw that is
used when focusing manually. With manual
close-up photography using the copy stand in
any situation or with the lens pointing down ,
if you turn the clamp screw to the ON position,
rotation of the focusing ring becomes
tight. This helps to prevent the rotation of the
focusing ring due to the lens's own weight
and avoid any shift in focus.
• When shooting in the autofocus mode, turn
the clamp screw to the OFF position.
Activating the autofocus mode while the
clamp screw is in the ON position slows
down the focusing speed.

If the clamp is to make manual focus easier, how can we explain why it makes D-FA50mm's manual focus harder (stiff and not smooth at all)?

[scratchpaddy]

This is not its purpose either. The manual says below. I think the original purpose is to prevent focus shift during critical focusing.

Hmm. The plot thickens.

Whatever the clamp's intended purpose is, it does make manual focus easier on the FA 100, and the manual never contradicts that. It doesn't even say that using it with AF is bad, just that it slows things down. I still wouldn't use the clamp with AF, though.

In any case, to the OP, your copy is not defective. The clamp is not supposed to stop the focusing ring from rotating entirely. It just adds a little resistance.

[SOldBear]

On my copy of FA Macro 50mm f/2.8, when the clamp is engaged, manually turning the focusing ring becomes extremely difficult. I think AF doesn't work, but I need to verify this (I've never engage the clamp when using AF).

Edited to add:

I verified it: when the clamp is engaged, the camera (K-7) doesn't attempt to AF at all.

[bdery]

If the clamp is to make manual focus easier, how can we explain why it makes D-FA50mm's manual focus harder (stiff and not smooth at all)?

A stiff ring is a good thing for manual focus (as long as it's not TOO stiff). With my previous FA50 macro the clamp just added a nice amount of friction so that the ring gave feedback when you moved it, instead of being lifeless as I wrote.

I think the manual pretty much sums up the intended use of the clamp. With my 50 there was never any zoom creep that I noticed but it might be different with the 100.