16-50 sdm - A new lease of life


Nov 13, 2010
105
5
18
Queenstown
#1
Ever since my 16-50 sdm died a year ago. I have not used it at all. Don't like to use manual focus. Thanks to fengwei who helped to disable the sdm, now my lens is back in action.:)
 

fengwei

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Aug 25, 2004
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#2
Haha, thanks for the beer ;p

And now my 1650 focuses a lot faster than it focused with SDM. And I do suggest all guys who are using SDM lenses like 1650/50135 on your K5/K5IIK5IIs cameras, better convert them to non-SDM lenses, you'd love them even more :cool:
 

jasonlel

Senior Member
Apr 9, 2010
590
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16
39
Malaysia/Singapore
#3
fengwei said:
Haha, thanks for the beer ;p

And now my 1650 focuses a lot faster than it focused with SDM. And I do suggest all guys who are using SDM lenses like 1650/50135 on your K5/K5IIK5IIs cameras, better convert them to non-SDM lenses, you'd love them even more :cool:
2 thumbs up!
 

fengwei

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Aug 25, 2004
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#4
This morning I tried the lens under good light, man, its AF speed can compare w/ 18135 I think. It's almost instant from minimum to infinity :cool:
 

gtl1987

New Member
Oct 28, 2008
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#9
Is there quick shift still with the screwdrive?
 

morganoh

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Dec 24, 2002
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#11
Actually I dont really understand.
Does it means that theres 2 motor built into the lens?
One SDM
One screw motor?

I though theres only one motor for the lens AF?
 

fengwei

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#12
Actually I dont really understand.
Does it means that theres 2 motor built into the lens?
One SDM
One screw motor?

I though theres only one motor for the lens AF?
SDM is inside the lens, screw driven motor is inside the camera. You can use either one to do AF w/ some SDM lenses like DA* 1650/50135/200/300 and etc, but you can't use both together. When SDM is working, camera motor will be disabled/disconnected, when camera motor is working, SDM will be disabled.

The firmware updating is to disable SDM motor so the camera would recognize the lens as non-SDM lens, so the camera motor will turn to drive the lens when doing AF.
 

Bridgerock

Senior Member
Nov 20, 2006
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#14
Is this 'enhancement' reversible? I do find the 16-50 AF faster on the K5IIs. But if the screw drive does boost the AF even faster, then its really worth to do this 'enhancement'. ;)
 

fengwei

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#15
So can I confirm that SDM is really slower than camera body motor?
In this (DA*1650) case, yes, I can confirm that. I think SDM motor is a bit too weak to drive the lens element quickly, the acceleration and deceleration during AF movement are pretty slow and obvious. While with the camera AF motor the acceleration and deceleration are almost non exist. It's not super fast purely because Pentax' AF module and software are not there yet.
 

fengwei

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#16
Is this 'enhancement' reversible? I do find the 16-50 AF faster on the K5IIs. But if the screw drive does boost the AF even faster, then its really worth to do this 'enhancement'. ;)
Yes, just write the original ROM file back to the lens, it'd go back to an SDM driven lens :)
 

Last edited:

dualie

New Member
Apr 10, 2006
384
2
0
#17
fengwei said:
Yes, just write the original ROM file back to the lens, it'd go back to an SDM driven lens :)
Just to verify that it still cannot be done through a K5? So will need your K7 to do the update.
 

canbedone

New Member
Nov 25, 2010
330
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#19
there is new update for K5 IIs?
 

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