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05-31-2013, 01:37 AM   #1
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Pentax K01 and AF on old sigma lens

Hello,

Could someone give his observations of how K01 works with old third party AF lenses.
I have one old Sigma 70-300 APO that i want to use. There are also some other old autofocus lenses that i also consider.

My concern is that K01 uses only CDAF for focusing and the old lenses are designed for PDAF systems. I see that some users as complaining that autofocus is very slow with such lenses.

BR

05-31-2013, 01:56 AM   #2
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QuoteOriginally posted by rdo Quote
Hello,

Could someone give his observations of how K01 works with old third party AF lenses.
I have one old Sigma 70-300 APO that i want to use. There are also some other old autofocus lenses that i also consider.

My concern is that K01 uses only CDAF for focusing and the old lenses are designed for PDAF systems. I see that some users as complaining that autofocus is very slow with such lenses.

BR
With a tele lens like that the AF will be slow. The K-01 works best with lenses that have a short focus throw, such as the limiteds.

Adam
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05-31-2013, 05:59 AM   #3
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Hi BR:

It depends on the lens. My K01 won't AF with the Sigma 18-250 HSM but will with an old Tamron 70-300.

Dale
05-31-2013, 06:22 AM   #4
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QuoteOriginally posted by DDoram Quote
Hi BR:

It depends on the lens. My K01 won't AF with the Sigma 18-250 HSM but will with an old Tamron 70-300.

Dale
Hi, this doesn't sound good at all.
Do you know why it will not work and is there any general rule which AF lenses will work.

05-31-2013, 06:38 AM   #5
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Every lens I've put on my k-01 has worked, and that's all of them in my signature (and more), though the screw drive ones are quite noisy. My roomate borrowed my old Pentax 28-80 for an anime con, and other than not being wide enough on her K-01 it worked well.
05-31-2013, 06:44 AM - 1 Like   #6
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QuoteOriginally posted by rdo Quote
Hi, this doesn't sound good at all.
Do you know why it will not work and is there any general rule which AF lenses will work.
I'm surprised the Tamron 70-300 works. Most variable-aperture zooms just don't let enough light in (especially at the long end) to get enough contrast to detect. They might work outside in bright sunlight, but proably not in shade or indoors.

Here's my general rule for AF lenses on the K-01: Short and bright = works alright. Long and slow = will not go.

05-31-2013, 07:30 AM   #7
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QuoteOriginally posted by rdo Quote
My concern is that K01 uses only CDAF for focusing and the old lenses are designed for PDAF systems.
I'm pretty sure that all lenses are "designed for PD AF", since CD AF is so new. CD AF on the K-01 was improved a lot with the firmware updates. My DA L 50-200 took forever to focus at fist, but after the update its actually usable. Not as fast as PD AF, but useable.
There was also a thread with a list of lenses and how well they focus on K-01. But it was user-submitted data and they didn't all use the firmware thats out now. If you find it, maybe someone tested that same lens. Also, its a bit random, because sometimes different lenses of similar focal length and aperture would perform differently.
05-31-2013, 07:55 AM   #8
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I have an old beater Sigma UC Zoom 70-210 that I've used a few times on the K-01 (v. 1.03), and it works, although it hunts a lot in low light. I don't use it much on the K-01 because it's not as sharp or fast-focusing as my DA 50-200 (and all the aperture numbers and focal lengths are worn off).

06-07-2013, 02:19 PM   #9
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Every lens except one I've thrown on my K-01 has worked. The only one that has given me trouble is a Tokina 35-70 f3.6. It hunts in what I consider decent light. In good light it's fine, but in indoor daytime light or heavily shaded, overcast light, it's rather awful. It's not terribly good for that on my K-x either, but it doesn't start hunting until the light is really fading when it's on the K-x. (FA 35-70 is much better in that regard)

That being said, my 28-210mm works great on the K-01, even though at full tele the aperture is f6.3. In good light focuses quick, in bad light still focuses, but it takes its time.

Charles.
06-08-2013, 09:43 AM   #10
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The K01 works with all screw drive lenses and the fact it won't work with my Sigma 18-250 is not a bid deal to me. I bought it to use small primes and manual focus lenses anyway.
06-10-2013, 11:15 AM   #11
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K-01/Sigma 70-300 DL Macro Super $45. Pre focus and AF doesn't search as much or just use manual w/K-01. Pansy on AF normal, yellow in macro. Shot in the last hour for your dining and dancing pleasure.

Last edited by lukulele; 06-30-2014 at 11:45 AM.
06-27-2013, 11:12 AM   #12
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I just want to add my K-01 doesn't work at all with the AF on my Sigma F1.4 50mm. It thinks its in focus and makes the confirmation beep ONLY when horribly out of focus. On my Tamron 18-200mm it takes incredibly long even in day light to focus. Very dissapointed. Didn't realize newer 3rd party lenses might have such trouble... probably would not have purchased if I knew, though I've got some great shots with the 40mm F2.8.
06-27-2013, 11:54 AM   #13
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QuoteOriginally posted by runintotherain Quote
I just want to add my K-01 doesn't work at all with the AF on my Sigma F1.4 50mm. It thinks its in focus and makes the confirmation beep ONLY when horribly out of focus. Didn't realize newer 3rd party lenses might have such trouble... probably would not have purchased if I knew.
Have you tried focus peaking (zooming in) with manual focus?
It works really well with my A50/1.2, even in really low light.
06-27-2013, 02:12 PM   #14
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Yeah I have tried that and I've got a manual 1.4 SMC that's much smaller than my Sigma AF 1.4 to do that with. I only bought the Sigma for the AF but it's wasted on the K-01. I wonder if the AF version of the 1.4 SMC 50mm actually focuses (not that I'd drop another couple hundred into one again - my first one fell apart). You're lucky to have the 1.2! I was eying that earlier today as I've done in the past...
06-27-2013, 02:34 PM   #15
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QuoteOriginally posted by runintotherain Quote
You're lucky to have the 1.2! I was eying that earlier today as I've done in the past...
I never trusted myself to be able to make good use of that lens on a DSLR,
so I didn't get one until I had the K-01.
Along with its useable apertures below f/2,
the absence of mirror shake on the K-01
gives an awesome hand-held low-light combination.
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