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01-26-2011, 10:21 PM   #181
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QuoteOriginally posted by builttospill Quote
The SDM lens will be a manual-focus lens sooner or later, but still delivers nice pictures. That's why they hold their value.
I can name you a few instances (including one I experienced myself) where the focus mechanism jammed altogether on the 50-135mm, both AF and MF. The focus ring just stops moving the focus mechanism. No harsh impacts, no undue stress, no abuse. There's a lot more wrong here than shoddy motors.

01-29-2011, 07:08 PM   #182
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I wonder if the weather sealing could be contributing to the problems? That is, if the motor is generating enough heat that can't escape, could it be damaging stuff? I know I was suddenly less enamored of the weather sealing on the K7 the first time I tried to use Live View during a heat wave.
01-29-2011, 07:48 PM   #183
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QuoteOriginally posted by pentup Quote
I wonder if the weather sealing could be contributing to the problems? That is, if the motor is generating enough heat that can't escape, could it be damaging stuff? I know I was suddenly less enamored of the weather sealing on the K7 the first time I tried to use Live View during a heat wave.
IF that was the case, then a (cheap) heat-sink clamped on the motor body should disperse enough residual heat into the other lens components, not to cause a problem. However, having pulled my 16-50 apart and freed the jammed motor, I can tell you there's already a lot of air around the motor, and I really can't see that there'd be a problem dispersing heat from it. There's a great mass of glass and aluminium around it, too, to soak up heat generally, and the lens vents into the camera body.

Really, though, I think you'd have to be running the AF continuously and for a very significant length of time for motor heat build-up to be even in question.

As for weather sealing being an issue for Live View, the gaps in a non-sealed body are so small that convective heat transfer isn't likely to be an issue there, either. I could be wrong, but I'd like to see some real, scientific tests to prove it before I'd believe it. I'm not suggesting there isn't an issue with high ambient temperatures and Live View, just that I doubt it's the weather sealing causing it.
01-29-2011, 10:02 PM   #184
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Got my 50-135 back from repair - everything seems to be fine. However, autofocus speed is a little slower I think. I recall the original SDM being pretty much press-BANG - traverses focal range so quickly you barely notice it. It now seems to take a tiny bit longer- still probably no more than half a second from near to far.

Are they possibly rolling out different replacement motors?

01-29-2011, 10:49 PM   #185
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QuoteOriginally posted by awolfe98 Quote
Are they possibly rolling out different replacement motors?
oh boy, here we go again
01-31-2011, 09:45 PM   #186
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QuoteOriginally posted by Hound Tooth Quote
oh boy, here we go again
I must have missed the previous discussion then - has this been suggested before?
01-31-2011, 09:59 PM   #187
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QuoteOriginally posted by awolfe98 Quote
I must have missed the previous discussion then - has this been suggested before?
Yes and all indications point to wishful thinking.
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