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02-10-2010, 03:03 AM   #1
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Do you find the KX autofocus speed abit slow compared to its competitors?

I don't know about the AF speed of the K7 as I have never tried it but I personally feel that the AF speed of the KX is not as fast when compared to its Canon and Nikon equivalents. I've tried my friend's Canon 500D and it seems to focus faster with just the kit lens compared to my KX with FA35. I tried taking a dance performance recently with the DA70 and it has abit of difficulty in focusing and catching up with the action too.

I remembered when I was using the Nikon D80 last time with 70-200 F2.8 and 18-200VR, I didn't encounter such problems. The focusing is faster and more accurate when taking events. So I guess Pentax AF speed is still abit lacking when compared to C and N?

02-10-2010, 03:42 AM   #2
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QuoteOriginally posted by aaronius Quote
So I guess Pentax AF speed is still abit lacking when compared to C and N?
That seems to be the consensus. Pentax cameras like to double-check. As a work-around, you can try continuous AF and spray and pray.
02-10-2010, 08:36 AM   #3
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Try some NiZn batteries. They make my autofocus motor run faster. That could help with focus lock.
02-10-2010, 09:52 AM   #4
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Canon and Nikon users find that ISO performance on their camera sucks.
They think that the Pentax K-m is better.
Hmmm....decisions..decisions..
I think, I need to look for more things to compare 'coz I'm not always satisfied with what I have and always see how it is always greener at the other side of the fence.
Canon XT was just 3fps when it came out..hmmmm..

02-10-2010, 03:04 PM   #5
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Hi guys...new one here.

Yes in my research, Canon weas much better at AF. It is considered to be the best there is. I found OLY and pentax to be about the same..The sony 230 was a bit better too.

But all things considered the k-x was a better camera and better price. Some times i just switch to manual focus.

My plan is to get better with this entry level and in a couple of years with better skills and with pentax hopefully getting a better AF..we can move up

I should add...when i did my 'testing' the KX wouldn't focus where the canon would...its not a question of speed so much, but wheterh it can focus in low lights..

Last edited by Littlejohn; 02-10-2010 at 05:00 PM. Reason: add comment
02-10-2010, 03:38 PM   #6
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Just to balance things up a bit, very few shots with 2 different lenses on a Canon 500D were actually in sharp focus in a review I read in a magazine recently. The Kx was spot on, as was a D90.
02-10-2010, 03:51 PM   #7
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QuoteOriginally posted by asdf Quote
Pentax cameras like to double-check.
I really think this is a myth asdf. (Along with the typical accompanying myth that other brands are faster but less accurate.) Bottom line is that SAFOX is just slow in low light. Tests like the ones popphoto has done for years confirm this. I think people attribute it to a "double check" because SAFOX gets "jerky" below about EV5. I notice it myself. AF speed is a Pentax weakness I admit. But Pentax also has many strengths.

These tests I posted before (not mine) show the jerkiness in dim light. I notice this on my Pentax cameras myself. I don't believe I would characterize it as double checking. More like: move, check, move check, move check, etc. Some lenses seem worse than others as well.

[YT]http://www.youtube.com/watch?v=ngUcQUchHEU[/YT]

Last edited by PentaxPoke; 02-10-2010 at 03:59 PM.
02-10-2010, 04:53 PM   #8
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wait, why isn't this a "POLL"...

02-10-2010, 07:13 PM   #9
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Haha ya I should have made it a poll. Can I still do it now?

QuoteOriginally posted by mtroute Quote
wait, why isn't this a "POLL"...
02-10-2010, 07:52 PM   #10
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Ya from watching the video, the 7D does seems to be noticeably faster than the K7 in AF but I guess that is to be expected as the 7D is supposed to be one of the fastest performers in terms of AF around.

I definitely love my KX and I agree that Pentax has many other strengths. But I just feel strange that my KX will be slower in AF compared to my old Nikon D80 which is old technology.

I am just wondering if it is due to the lenses used? I used to take events with my Nikon D80 + Tamron 17-50 + 18-200VR + 70-200VR and AF is really fast and accurate even in low-lighting. My KX is coupled with FA35 and DA70 and AF hunts. Is it because the Pentax lenses I owned are using screw-mount motor instead of SDM?

QuoteOriginally posted by PentaxPoke Quote
I really think this is a myth asdf. (Along with the typical accompanying myth that other brands are faster but less accurate.) Bottom line is that SAFOX is just slow in low light. Tests like the ones popphoto has done for years confirm this. I think people attribute it to a "double check" because SAFOX gets "jerky" below about EV5. I notice it myself. AF speed is a Pentax weakness I admit. But Pentax also has many strengths.

These tests I posted before (not mine) show the jerkiness in dim light. I notice this on my Pentax cameras myself. I don't believe I would characterize it as double checking. More like: move, check, move check, move check, etc. Some lenses seem worse than others as well.

[YT]http://www.youtube.com/watch?v=ngUcQUchHEU[/YT]
02-10-2010, 07:53 PM   #11
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And guys, just wondering if using C-AF will help the KX autofocus faster (hunt less) if I am taking performances and events?
02-10-2010, 09:48 PM   #12
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QuoteOriginally posted by PentaxPoke Quote
I really think this is a myth asdf. (Along with the typical accompanying myth that other brands are faster but less accurate.) Bottom line is that SAFOX is just slow in low light. Tests like the ones popphoto has done for years confirm this. I think people attribute it to a "double check" because SAFOX gets "jerky" below about EV5. I notice it myself. AF speed is a Pentax weakness I admit. But Pentax also has many strengths.
What myth? How are you even disagreeing with me? The Pentax rangefinder/phase detection has to re-check because its first reading is inaccurate. I didn't even comment on the accuracy of other rangefinders/phase detection systems. Of course it has to double or triple check while jerking the lens--because it's wrong the first time.

The video you keep spamming is ridiculous, btw. They should put the same lens on both cameras...say a Tamron 90 f/2.8. Pentax would still be slower, but this "comparison" would be less ridiculous.

Last edited by asdf; 02-10-2010 at 10:16 PM.
02-10-2010, 10:28 PM   #13
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QuoteOriginally posted by asdf Quote
The video you keep spamming is ridiculous, btw. They should put the same lens on both cameras...say a Tamron 90 f/2.8. Pentax would still be slower, but this "comparison" would be less ridiculous.
I didn't know I was spamming anyone. I find that video interesting. I am a visual person, and I think it is instructive to actually see focusing speed instead of talking about it.

Don't you find the 50-135 video slow? That is how I remember mine focusing. The 18-250 seemed slower than I remember as well, but I always used that lens outdoors.
02-10-2010, 10:38 PM   #14
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QuoteOriginally posted by PentaxPoke Quote
Don't you find the 50-135 video slow? That is how I remember mine focusing. The 18-250 seemed slower than I remember as well, but I always used that lens outdoors.
Here's the Tokina 50-135 on a Canon (it's relatively slow, as well):

[yt]http://www.youtube.com/watch?v=l5FgZToE7uQ[/yt]
02-10-2010, 10:52 PM   #15
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A lot of it has to do with the lens. But I really don't feel any difference in speed between my K-x with the kit lens and how my 40D felt with the 85mm f1.8 (reputed as one of Canon's faster focusers) if I'm using them in good light. Low light, the Canon held the high ground for the obvious reasons.

Focus speed with my M 50mm f1.7, on the other hand, is a different story altogether. Especially when I'm shooting wide open, the focus system seems to like to check, double-check, and then check once more before finally deciding it's in focus.
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