Pentax k1 and with crop lenses

giselag · 12-03-2017, 03:06 PM

I got great information about using the 50mm DA F1.8 lens with the K1. Thanks for the info and the sample pics.

Does anyone have experiences using a the K1 with a DA 16-85mm lens and /or 10-20mm sigma lens?

Would love to know how they work in crop mode (how does it affect the megapixels/ image quality) and do they work in FF mode?

I currently use them with my K3. Thinking about upgrading to the k1 body but cant afford to buy new lenses at the moment.

Thanks in advance for the info.

Adam · 12-03-2017, 03:16 PM

The 16-85mm only works in crop mode, so for a walkaround lens you'd want something with FF coverage, like the 24-70 or the 28-105mm. Not sure about the Sigma but it probably doesn't cover FF until later in the range.

In crop mode you get 15 megapixels, so quite a bit less resolution than the K-3. Other aspects of the image quality are unchanged.

**kiwi_jono** · 12-03-2017, 11:27 PM

I'm not sure which Sigma 10-20 you are talking about but I can comment on the Sigma Ex 10-20 f3.5:
* It has strong vignetting in FF from 10 - 14mm
* Vignetting wise its not bad from 15 - 20mm.
* In terms of IQ though the corners are pretty mushy and so I do not use mine in FF.

surfar · 12-03-2017, 11:35 PM

Sigma 10-20 + 1.4x TC,its useable right thru the zoom range, corners are not sharp but they can be cropped out.

pathdoc · 12-04-2017, 04:52 AM

There is at least one wide-angle Sigma zoom that is a DG (full frame) and another, very similar IIRC, that is DC (crop). So one must be careful.

funktionsfrei · 12-05-2017, 12:23 PM

Originally posted by pathdoc

There is at least one wide-angle Sigma zoom that is a DG (full frame)

Yes, but that is not a 10-20, but a 12-24. This is the widest UW zoom lens out there for the K bayonet, there is but one UW prime that is even wider - the Irix 11mm.

For whatever dumb stupid reasons, Sigma has ceased manufacturing the 12-24 with Pentax mount, just about the time when the K-1 hit the market (thus being the perfect moment to make that lens interesting again, since it's a full-frame lens). If you're lucky, you can get a used copy. If you're really lucky, that used copy is in good condition.

The current incarnation, the "12-24mm F4 DG HSM Art" is not available in Pentax mount.
Only it's predecessors, the "12-24mm 4.5-5.6 II DG HSM" and the older "12-24mm 4.5-5.6 EX DG Asp IF" were produced with Pentax mount.

(And no, the Pentax SMC DA 12-24 is not a full frame lens, so it's no contender)

**clackers** · 12-05-2017, 05:49 PM

Originally posted by funktionsfrei

Yes, but that is not a 10-20, but a 12-24. ...
(And no, the Pentax SMC DA 12-24 is not a full frame lens, so it's no contender)

I bought a refurbished Sigma 12-24 DG this year, Funktionsfrei ... it's not bad.

I also have the Pentax 12-24 and it's excellent. From 17mm on it works very well with the K-1 in full frame mode. For someone looking to go autofocus and less than 24 or 28mm, I'd recommend it, it's pretty good.

12-03-2017, 03:06 PM	#1
giselag Forum Member Join Date: Dec 2015 Photos: Gallery Posts: 58	Pentax k1 and with crop lenses I got great information about using the 50mm DA F1.8 lens with the K1. Thanks for the info and the sample pics. Does anyone have experiences using a the K1 with a DA 16-85mm lens and /or 10-20mm sigma lens? Would love to know how they work in crop mode (how does it affect the megapixels/ image quality) and do they work in FF mode? I currently use them with my K3. Thinking about upgrading to the k1 body but cant afford to buy new lenses at the moment. Thanks in advance for the info.

12-03-2017, 03:16 PM	#2
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,595	The 16-85mm only works in crop mode, so for a walkaround lens you'd want something with FF coverage, like the 24-70 or the 28-105mm. Not sure about the Sigma but it probably doesn't cover FF until later in the range. In crop mode you get 15 megapixels, so quite a bit less resolution than the K-3. Other aspects of the image quality are unchanged. 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 purchasing one of our Pentax eBooks. 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:

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12-03-2017, 11:27 PM	#3
kiwi_jono Loyal Site Supporter Join Date: Dec 2009 Location: Christchurch, New Zealand Photos: Gallery \| Albums Posts: 2,437	I'm not sure which Sigma 10-20 you are talking about but I can comment on the Sigma Ex 10-20 f3.5: * It has strong vignetting in FF from 10 - 14mm * Vignetting wise its not bad from 15 - 20mm. * In terms of IQ though the corners are pretty mushy and so I do not use mine in FF.

12-03-2017, 11:35 PM	#4
surfar Pentaxian Join Date: Jan 2015 Location: mid nth coast,nsw Photos: Gallery Posts: 6,141	Sigma 10-20 + 1.4x TC,its useable right thru the zoom range, corners are not sharp but they can be cropped out.

12-04-2017, 04:52 AM	#5
pathdoc Pentaxian Join Date: Mar 2015 Photos: Gallery \| Albums Posts: 6,381	There is at least one wide-angle Sigma zoom that is a DG (full frame) and another, very similar IIRC, that is DC (crop). So one must be careful.

12-05-2017, 12:23 PM	#6
funktionsfrei Senior Member Join Date: Feb 2012 Posts: 183	Originally posted by pathdoc There is at least one wide-angle Sigma zoom that is a DG (full frame) Yes, but that is not a 10-20, but a 12-24. This is the widest UW zoom lens out there for the K bayonet, there is but one UW prime that is even wider - the Irix 11mm. For whatever dumb stupid reasons, Sigma has ceased manufacturing the 12-24 with Pentax mount, just about the time when the K-1 hit the market (thus being the perfect moment to make that lens interesting again, since it's a full-frame lens). If you're lucky, you can get a used copy. If you're really lucky, that used copy is in good condition. The current incarnation, the "12-24mm F4 DG HSM Art" is not available in Pentax mount. Only it's predecessors, the "12-24mm 4.5-5.6 II DG HSM" and the older "12-24mm 4.5-5.6 EX DG Asp IF" were produced with Pentax mount. (And no, the Pentax SMC DA 12-24 is not a full frame lens, so it's no contender)

12-05-2017, 05:49 PM	#7
clackers Otis Memorial Pentaxian Join Date: Jul 2013 Location: Melbourne Photos: Albums Posts: 16,397	Originally posted by funktionsfrei Yes, but that is not a 10-20, but a 12-24. ... (And no, the Pentax SMC DA 12-24 is not a full frame lens, so it's no contender) I bought a refurbished Sigma 12-24 DG this year, Funktionsfrei ... it's not bad. I also have the Pentax 12-24 and it's excellent. From 17mm on it works very well with the K-1 in full frame mode. For someone looking to go autofocus and less than 24 or 28mm, I'd recommend it, it's pretty good.