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02-08-2010, 09:47 PM   #1
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D-FA 100mm macro focus ring

Actually I just received a used Samsung's version of this lens. Before this lens, I have two others lenses with quick-shift (all Samsung's clone..), 18-55mm and 12-24mm. But the focus ring of my 100mm macro is different than the other two.

They all can be turned freely in AF mode. With the 18-55mm and 12-24mm, the focus ring can be turned from minimum distance to infinity, and will stop at both end, can't be turned further. However, on the 100mm macro, even after it reaches minimum distance / infinity, i can still turn the focus ring. I don't need to put force but I do feel a little friction happening there. This friction only occurs when the focus ring turned further from minimum distance or infinity. Is this normal? Can anyone with D-FA 100mm macro or Samsung D-Xenon 100mm macro confirm this? Thank you!

02-09-2010, 12:01 AM   #2
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QuoteOriginally posted by sajah Quote
Actually I just received a used Samsung's version of this lens. Before this lens, I have two others lenses with quick-shift (all Samsung's clone..), 18-55mm and 12-24mm. But the focus ring of my 100mm macro is different than the other two.

They all can be turned freely in AF mode. With the 18-55mm and 12-24mm, the focus ring can be turned from minimum distance to infinity, and will stop at both end, can't be turned further. However, on the 100mm macro, even after it reaches minimum distance / infinity, i can still turn the focus ring. I don't need to put force but I do feel a little friction happening there. This friction only occurs when the focus ring turned further from minimum distance or infinity. Is this normal? Can anyone with D-FA 100mm macro or Samsung D-Xenon 100mm macro confirm this? Thank you!
That is normal for Pentax quick shift lenses. Both my DA* lenses work exactly like that. The 12-24 does not, as you note.
02-09-2010, 01:55 AM   #3
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Phew, that's a relieve. I thought was a defect.. The price was quite cheap which only made me more suspicious
Thanks again!
02-09-2010, 02:02 AM   #4
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Hi sajah,

The focus ring action on your lens is normal for this model, but unlike most DA series Quick Shift lenses in that the ring does not stop at the normal ends of travel (though the travel of the focusing helicoid does have definite stops at both ends).

The clamp allows you to "lock" the focus distance at a given point, but it doesn't lock solidly, and can be overridden with enough force. The purpose of the clamp is to allow you to lock the ring at a chosen magnification if you desire.

Scott

02-09-2010, 09:31 PM   #5
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I see. Thanks for the info, Scott. I was wondering about the clamp too (but forgot to ask), since I've tried to lock it and noticed I still could turn the ring, albeit harder.
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