Question about different Pentax mounts

TXPentaxK50 · 08-17-2017, 02:32 PM

I am looking at purchasing a Sigma 70-200mm f/2.8 EX DG APO OS HSM II, to utilize with my Pentax K-50.

However, there has been some cautionary language about this lens not being compatible with certain Pentax mounts in terms of of the autofocus feature.

One review states: "The HyperSonic Motor (HSM) focusing system promises fast, silent and accurate autofocus for users of all brands of DSLR, although Pentax users should be aware that this lens is effectively of 'KAF-3' mount specification, and therefore won't focus on bodies which don't support SDM lenses."

So...will this lens work with the K-50?

I called Sigma and Pentax, and there was a lot of fumbling and mumbling - not many straight answers. 😎

Giklab · 08-17-2017, 02:37 PM

Only some very early DSLRs don't support HSM. The lens will work fine on your K-50.

**disconnekt** · 08-17-2017, 02:41 PM

On the older cameras they won't work, newer ones within the last few years (like the k50) will work fine with it

Adam · 08-17-2017, 02:52 PM

Originally posted by TXPentaxK50

I am looking at purchasing a Sigma 70-200mm f/2.8 EX DG APO OS HSM II, to utilize with my Pentax K-50.

However, there has been some cautionary language about this lens not being compatible with certain Pentax mounts in terms of of the autofocus feature.

One review states: "The HyperSonic Motor (HSM) focusing system promises fast, silent and accurate autofocus for users of all brands of DSLR, although Pentax users should be aware that this lens is effectively of 'KAF-3' mount specification, and therefore won't focus on bodies which don't support SDM lenses."

So...will this lens work with the K-50?

I called Sigma and Pentax, and there was a lot of fumbling and mumbling - not many straight answers. ��

Yes it will work. KAF3 lenses will focus on any Pentax DSLR from 2007 or newer, plus the K10D w/ 1.30+ firmware.

A simple way of looking at Pentax lens compatibility (which holds true with all K-mount cameras) is that the camera supports ALL lenses that were released before it. Most lenses newer than the camera will work as well, but this of course can't be guaranteed. In the K-50's case, all newer Pentax lenses also work.

Adam
PentaxForums.com Webmaster (Site Usage Guide | Site Help | My Photography)

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**boriscleto** · 08-17-2017, 03:34 PM

There might be issues with the K-1 if the lens has the wrong identifier in firmware. Sigma can flash the firmware to fix it. But it should work fine on a K-50.

TXPentaxK50 · 08-17-2017, 05:30 PM

Great info. Thank you so much !

Caribe · 08-19-2017, 07:26 AM

I bought one used from adorama a couple of months ago. I've only had time for test shots 😞 with my k30 and k3. So far so good! I'm guessing some new k1 owner traded it in.
But this makes me wonder if it will also be compatible with the kp, or the probable "k3mk iii"? I'm interested in replacing the k30 with a kp as the price has fallen. I like the sigma so far, specially for the price.

Anyone has the sigma-kp combo?

Giklab · 08-20-2017, 04:28 AM

Originally posted by Caribe

I bought one used from adorama a couple of months ago. I've only had time for test shots 😞 with my k30 and k3. So far so good! I'm guessing some new k1 owner traded it in.
But this makes me wonder if it will also be compatible with the kp, or the probable "k3mk iii"? I'm interested in replacing the k30 with a kp as the price has fallen. I like the sigma so far, specially for the price.

Anyone has the sigma-kp combo?

Sigma usually updates their firmware for use with newer cameras. At worst you'd have to send the lens in.

08-17-2017, 02:32 PM	#1
TXPentaxK50 Junior Member Join Date: Aug 2017 Posts: 45	Question about different Pentax mounts I am looking at purchasing a Sigma 70-200mm f/2.8 EX DG APO OS HSM II, to utilize with my Pentax K-50. However, there has been some cautionary language about this lens not being compatible with certain Pentax mounts in terms of of the autofocus feature. One review states: "The HyperSonic Motor (HSM) focusing system promises fast, silent and accurate autofocus for users of all brands of DSLR, although Pentax users should be aware that this lens is effectively of 'KAF-3' mount specification, and therefore won't focus on bodies which don't support SDM lenses." So...will this lens work with the K-50? I called Sigma and Pentax, and there was a lot of fumbling and mumbling - not many straight answers. 😎

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08-17-2017, 02:37 PM	#2
Giklab Veteran Member Join Date: Jan 2012 Location: Slovenia Photos: Gallery Posts: 2,182	Only some very early DSLRs don't support HSM. The lens will work fine on your K-50.

08-17-2017, 02:41 PM	#3
disconnekt Site Supporter Join Date: Oct 2011 Location: Riverside, CA Photos: Albums Posts: 1,577	On the older cameras they won't work, newer ones within the last few years (like the k50) will work fine with it

08-17-2017, 02:52 PM	#4
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,166	Originally posted by TXPentaxK50 I am looking at purchasing a Sigma 70-200mm f/2.8 EX DG APO OS HSM II, to utilize with my Pentax K-50. However, there has been some cautionary language about this lens not being compatible with certain Pentax mounts in terms of of the autofocus feature. One review states: "The HyperSonic Motor (HSM) focusing system promises fast, silent and accurate autofocus for users of all brands of DSLR, although Pentax users should be aware that this lens is effectively of 'KAF-3' mount specification, and therefore won't focus on bodies which don't support SDM lenses." So...will this lens work with the K-50? I called Sigma and Pentax, and there was a lot of fumbling and mumbling - not many straight answers. �� Yes it will work. KAF3 lenses will focus on any Pentax DSLR from 2007 or newer, plus the K10D w/ 1.30+ firmware. A simple way of looking at Pentax lens compatibility (which holds true with all K-mount cameras) is that the camera supports ALL lenses that were released before it. Most lenses newer than the camera will work as well, but this of course can't be guaranteed. In the K-50's case, all newer Pentax lenses also work. Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

08-17-2017, 03:34 PM	#5
boriscleto Loyal Site Supporter Join Date: Dec 2009 Location: North Syracuse, NY Photos: Gallery Posts: 16,245	There might be issues with the K-1 if the lens has the wrong identifier in firmware. Sigma can flash the firmware to fix it. But it should work fine on a K-50.

08-17-2017, 05:30 PM	#6
TXPentaxK50 Junior Member Join Date: Aug 2017 Posts: 45 Original Poster	Great info. Thank you so much !

08-19-2017, 07:26 AM	#7
Caribe Forum Member Join Date: Jan 2015 Posts: 90	I bought one used from adorama a couple of months ago. I've only had time for test shots 😞 with my k30 and k3. So far so good! I'm guessing some new k1 owner traded it in. But this makes me wonder if it will also be compatible with the kp, or the probable "k3mk iii"? I'm interested in replacing the k30 with a kp as the price has fallen. I like the sigma so far, specially for the price. Anyone has the sigma-kp combo?

08-20-2017, 04:28 AM	#8
Giklab Veteran Member Join Date: Jan 2012 Location: Slovenia Photos: Gallery Posts: 2,182	Originally posted by Caribe I bought one used from adorama a couple of months ago. I've only had time for test shots 😞 with my k30 and k3. So far so good! I'm guessing some new k1 owner traded it in. But this makes me wonder if it will also be compatible with the kp, or the probable "k3mk iii"? I'm interested in replacing the k30 with a kp as the price has fallen. I like the sigma so far, specially for the price. Anyone has the sigma-kp combo? Sigma usually updates their firmware for use with newer cameras. At worst you'd have to send the lens in.

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