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12-16-2013, 08:21 AM   #1
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K3 versus K5 Autofocus Performance

I have found various comparisons online on the K3 versus the K5II/IIS. But can anyone comment on the difference in autofocus (speed, hit rate, and low light performance) between the K3 and the K5. I am considering an upgrade to the K3, but am also considering switching to another system. My primary use is wildlife/birds, and the lens used the most is the DA*300mm.

12-16-2013, 09:01 AM   #2
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According one of the reviews, the K-3 is faster than the D7100 for focusing, but the D7100 is slightly better for tracking, personally, those are the only two systems I'd consider.
I seriously doubt you'll find a better system for what you want to do.

The images on this page show you what the Pentax can do…

https://www.pentaxforums.com/forums/122-lens-clubs/55946-300mm-plus-lens-club...enses-683.html

Here's sampling of my own work with an A-400.

2013-12-13
Camera: Pentax K-3
Lens: Pentax SMC A-400mm
ISO- 800
Aperture: ƒ8
Shutter: AV mode, shutter speeds 1/1000 1/3000

The day starts shooting through the kitchen window , birds out in the maple trees apparently eating seeds.



And a woodpecker on a tree.



Then moving outside. It's minus 20 today, even in full outdoor gear, it was chilly.



The male Purple Finches went straight to the feeders, I couldn't get any pictures of them anywhere else.



The females were more co-operative…





We also had a group of Goldfinches there as well.



And even a rodent.

12-16-2013, 09:05 AM   #3
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QuoteOriginally posted by jerbro Quote
I have found various comparisons online on the K3 versus the K5II/IIS. But can anyone comment on the difference in autofocus (speed, hit rate, and low light performance) between the K3 and the K5. I am considering an upgrade to the K3, but am also considering switching to another system. My primary use is wildlife/birds, and the lens used the most is the DA*300mm.
It's much much better. I was shooting a client meeting this past weekend, and every single shot was in focus, despite difficult lighting. F* 300 is also much more accurate and responsive. It just works.

Going from a K10D/K7 to the K5 was a jump in performance. It's easily the same magnitude from K5 to K3.
12-16-2013, 10:27 AM   #4
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Does anyone that's gone from K-5 to K-3 have any direct experience of the AF speed/accuracy/tracking with the Sigma 50-500?

12-16-2013, 10:39 AM   #5
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If it's screw drive expect faster. If it's electric drive expect the same speed in the movement of the lens elements, but a faster, more decisive focus lock.
12-16-2013, 12:02 PM   #6
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QuoteOriginally posted by normhead Quote
If it's screw drive expect faster. If it's electric drive expect the same speed in the movement of the lens elements, but a faster, more decisive focus lock.
I'm just wondering if they made the screw drive too fast. I have three Tamron lenses with screw drive and they look and sound like they're suffering from the very quick acceleration and even worse when running into the end stops, or perhaps a better word would be crashing into the end stops. The most worrying is the Tamron 90 Macro which gets really hammered into the infinity end stop when it doesn't acquire focus first time. Focus tracking with it is quite unbearable to hear. Its like using a hammer to adjust a microscope.

I don't know if the behavior is the same or more gentle with Pentax screw drives as the only one I have is the plastic 18-55. I've tried that and I'm quite sure it would quickly be rattled to pieces but that is far from being representative of Pentax lenses in general.

Maybe control of acceleration in AF is something to put in firmware updates, unless of course they have a cunning plan to put all non Pentax lenses out of action
12-16-2013, 12:58 PM   #7
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QuoteOriginally posted by lister6520 Quote
I'm just wondering if they made the screw drive too fast. I have three Tamron lenses with screw drive and they look and sound like they're suffering from the very quick acceleration and even worse when running into the end stops, or perhaps a better word would be crashing into the end stops. The most worrying is the Tamron 90 Macro which gets really hammered into the infinity end stop when it doesn't acquire focus first time. Focus tracking with it is quite unbearable to hear. Its like using a hammer to adjust a microscope.

I don't know if the behavior is the same or more gentle with Pentax screw drives as the only one I have is the plastic 18-55. I've tried that and I'm quite sure it would quickly be rattled to pieces but that is far from being representative of Pentax lenses in general.

Maybe control of acceleration in AF is something to put in firmware updates, unless of course they have a cunning plan to put all non Pentax lenses out of action
I own a couple of FA limiteds and DA limiteds and they all seem to be fine on the K3. Zippy, except for the DFA 100 macro which is what it is.
12-16-2013, 01:39 PM   #8
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My Sigma 70-300 refused to focus in low light and then the return on the zoom ring broke. I don't know if that had anything to do with the faster AF screw, but my suspicion is, Pentax designed a spec that could be upgrades later with a faster screw, everyone else designed for the fastest speed with the available screw speed. When Pentax upped the screw speed, everyone else's specs were inadequate. Just a guess. All my Pentax lenses work just fine.

12-16-2013, 01:55 PM   #9
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QuoteOriginally posted by lister6520 Quote
I'm just wondering if they made the screw drive too fast. I have three Tamron lenses with screw drive and they look and sound like they're suffering from the very quick acceleration and even worse when running into the end stops, or perhaps a better word would be crashing into the end stops. The most worrying is the Tamron 90 Macro which gets really hammered into the infinity end stop when it doesn't acquire focus first time. Focus tracking with it is quite unbearable to hear. Its like using a hammer to adjust a microscope.
You should hear the FA100-300 f4,7 mounted on the K20D... You can FEEL the gears engaging when you half-pressed the shutter, the torque is that strong. I would not worry about your lenses.
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