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10-16-2010, 07:37 AM   #1
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pentax k5 screw motor

I've read somewhere that the screw motor in the k5 is "faster" ... is that true? Has anyone tried AF with a 31 limited? how was it? faster?

i'm dreaming of a perfect on-the-go package for me... k5 + 31/1.8 + 55-300 low light capability for shooting climbing indoor and tele for outdoors ))

10-16-2010, 07:49 AM   #2
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I'm not sure the motor itself is faster, but as AF algorithms are improved AF will lock faster. This should improve AF on any lens.
But I haven't tested K-5, so I can not tell for sure.
10-16-2010, 07:50 AM   #3
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I'm also interested in this. I wonder how much of a factor the speed or strength of a motor is? The main point that I'm driving at is, does SDM have a higher capacity for speed that screw drive. If the AF processing brain of the K-5 was 5 times faster would screw drive speed max out, where SDM could keep up? I guess I've always thought that up to now the AF speed of the body was the limiter of everything.
10-16-2010, 08:51 AM   #4
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I have read with interest the screwdrive observations and have been impressed on several points. First the overall performance - speed to lock and then the locking process. All of this indicates much improved motor control in terms of "sliding" in to the designated position and stopping (not overshooting and then having to back up). I don't know about a more powerful motor, but Pentax appears to have found better control along with much better processing between the AF sensor and the positioning motor.



10-16-2010, 10:11 AM   #5
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I just tried the 31 on my K5 and K7 to try and see if I could perceive any improvement. The K5 feels like it is a bit more decisive and locks a little quick. I don't think the motor is "faster', just doesn't do (as many of) the little micro-corrections at the end. Focusing back and forth between two objects at different distances away, the K7 took 11 seconds to lock the times while the K5 took about 9. Hardly scientific, but it was repeatable and matches the general impression I get when shooting the K5 vs the K7.
10-16-2010, 05:16 PM   #6
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tnx!
10-16-2010, 05:23 PM   #7
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Someone said in another thread that the K5's AF is godly- I wouldn't be surprised if it were a combination of improvements to both the motor and the AF sensor.

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10-16-2010, 05:34 PM   #8
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I like to know whether on the menu on new Pentax DSLR (K-5 or Kr) has an option for choosing AF mode between SDM or Srewdriver.
I thought this feature is very useful for users to use their TC (Pentax has not come out with TC that work on SDM lens).

10-16-2010, 06:45 PM   #9
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That's a good question. I will check it out tomorrow as there are a lot of DA* lenses that need screw drive.
10-16-2010, 06:53 PM   #10
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QuoteOriginally posted by RTogog Quote
I like to know whether on the menu on new Pentax DSLR (K-5 or Kr) has an option for choosing AF mode between SDM or Srewdriver.
I thought this feature is very useful for users to use their TC (Pentax has not come out with TC that work on SDM lens).
I don't think there is any feature in the menu or custom functions to allow you to override an SDM drive to allow the use of the secondary screw mechanism (I've looked through the menus quite a few times and the user guide as well). Would be nice to have that option, and it would be an easy addition to the software, but I have a feeling Pentax has no intention of adding that feature (if they haven't already via firmware updates or in either of the last few body releases).
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