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01-05-2010, 09:34 PM   #1
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Okay, is this normal?

I have a 18-55 K-x Kit Lens. I don't know if this lens is a quick shift lens but when it's on Auto Focus, I can still move the focus ring after the auto focusing. While I turn it, I feel a smooth and buttery mechanical movement inside. Is this normal?

ps - if it doesn't have quick shift, is it normal for me to be able to rotate it while on auto focus? When I do put it on MF and rotate it, the rotation has much less friction, almost none

Thanks

01-05-2010, 10:16 PM   #2
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If it's the Mk I or Mk II (not DA-L) then it has quick shift.
The movement you describe is normal.
If you have a DA-L and are still able to quick shift then lucky you.
01-05-2010, 10:35 PM   #3
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QuoteOriginally posted by Ash Quote
If it's the Mk I or Mk II (not DA-L) then it has quick shift.
The movement you describe is normal.
If you have a DA-L and are still able to quick shift then lucky you.
yes Ash, I have the White K-x with the DAL Kit lens. I just needed to know if I am not forcing something that is not suppose to be rotating while in AF mode. Am I straining the motor or am I really lucky
01-05-2010, 10:45 PM   #4
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When you quick shift with a lens that has this feature, it feels loose and you feel no friction against the ring. The DA L doesn't have quick shift so I wouldn't recommend moving the ring when it's on AF. The smooth grind when you move the ring while in AF is normal but you're not supposed to do it as it could wear out the gears of your screw-drive motor.

01-05-2010, 10:48 PM   #5
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thanks Dave, that's what i've been thinking. I wonder why they designed it so it's able to rotate even in AF mode. I'd like to hear from other DAL users if this is possible on their lens.
01-06-2010, 12:53 AM   #6
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The quick shift lenses disengage once focus has locked, allowing very free fine focusing.
I'd suppose your DAL wouldn't be permitting such easy fine focusing and you may be forcing the AF mechanism by doing so.

Definitely don't risk it.
01-06-2010, 07:34 AM   #7
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QuoteOriginally posted by joodiespost Quote
thanks Dave, that's what i've been thinking. I wonder why they designed it so it's able to rotate even in AF mode. I'd like to hear from other DAL users if this is possible on their lens.
How much anti-rotation torque do you think you should get from a mechanism that is powered by 4 AA cells? The mechanism provides enough stiffness that so it doesn't move when bumped. But it would take a cog or something to keep if from being turned when "cranked" on.
01-06-2010, 02:16 PM   #8
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QuoteOriginally posted by DonP Quote
How much anti-rotation torque do you think you should get from a mechanism that is powered by 4 AA cells? The mechanism provides enough stiffness that so it doesn't move when bumped. But it would take a cog or something to keep if from being turned when "cranked" on.
Given the gearing, you might be surprised.

01-06-2010, 03:15 PM   #9
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QuoteOriginally posted by Oggy Quote
Given the gearing, you might be surprised.
Nah... the plastic gears will strip first.
01-06-2010, 03:39 PM   #10
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Don, i initially thought there might be some locking mechnism that would prevent the rotation once focus is achieved.
01-06-2010, 06:53 PM   #11
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In order for their to be a mechanical lock you'd have to have some sort of pawl that would latch into teeth or some similar mechanism. The problem with that is there would then be discrete steps instead of an infinite number of focus points. What if the actual focus was found to be between two steps of a mechanical lock? You'd either be near-sighted or far-sighted. No one would buy a camera that by design couldn't focus where it needed to be under common circumstances.
01-06-2010, 07:59 PM   #12
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i didn't know a stepping system was necessary for rotation blocking devices. I'm no engineer but are you saying all lenses without quickshift will be overrideable with small force?
01-07-2010, 08:20 AM   #13
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I think the force might vary but, yes, I do believe they can all be overridden.
01-07-2010, 09:04 AM   #14
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QuoteOriginally posted by joodiespost Quote
i didn't know a stepping system was necessary for rotation blocking devices. I'm no engineer but are you saying all lenses without quickshift will be overrideable with small force?
QuoteOriginally posted by DonP Quote
I think the force might vary but, yes, I do believe they can all be overridden.
Yep - in my experience, non quick shift lenses are fairly easy to override, and it sure seems like a bad idea (I've only done it by accident, thinking I was in MF) - especially if you were to try to turn it quickly .
01-08-2010, 03:59 AM   #15
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QuoteOriginally posted by heliphoto Quote
Yep - in my experience, non quick shift lenses are fairly easy to override, and it sure seems like a bad idea (I've only done it by accident, thinking I was in MF) - especially if you were to try to turn it quickly .

Spot on Heli - it's a great way of letting the smoke out, likely as not from the camera body. Expensive.
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