Sigma 18-35mm on the K3iii?

**bobbotron** · 11-02-2021, 08:23 AM

I'm really interested in this lens for the K3iii. Bit of a dark horse given the mixed feedback on autofocus, have to imagine the better AF of the K3iii would help it out? Anyone tried this combo? I'm looking for a fast zoom lens for covering indoor events, I'm thinking either this or the new 16-50 would be good.

Kozlok · 11-02-2021, 09:25 AM - **2 Likes**

I have the 18-35, and have used it on my K3III (but only about 250 shots total). It has maybe a bit worse keeper rate than my 16-85, but not unreasonably so. On my KS2, that lens worked well in single point focus mode, but not so well in multi-point mode. The K3III seems much more adept at managing the lens. Setting Autofocus to Auto multi-point mode and taking pictures of the grandkids worked out very well. Again, not a perfect keeper rate, but not bad.

I looked through a sequence of 11 shots at f1.8, and only 2 of those weren't focused on the eye. There were 2 more where it was just off the eye, but good enough at normal viewing magnification. 7 were basically perfectly focused on eyes in the shots. These were in good light. Indoors, my keeper rate was worse, maybe 20% were just terrible, and maybe another 20% where it focused on some random thing like a coffee cup. Again, not amazing, but workable.

At f2.8, my keeper rate seems to improve dramatically, with maybe 5% of shots just rubbish, and the rest better than adequate. By f5.6, it seems as good as any lens.

Here's a shot at f2.8 to whet your appetite.

AfterPentax Mark II · 11-02-2021, 09:54 AM - **1 Like**

Originally posted by bobbotron

I'm really interested in this lens for the K3iii. Bit of a dark horse given the mixed feedback on autofocus, have to imagine the better AF of the K3iii would help it out? Anyone tried this combo? I'm looking for a fast zoom lens for covering indoor events, I'm thinking either this or the new 16-50 would be good.

It is a no brainer: Why support Sigma instead of the company that made that fabulous K-3 Mark III. They deserve some support, don't they? Go for that new 16-50!

abraswell · 11-02-2021, 10:03 AM

If you don't mind shooting in Live View 100% of the time is a good lens. Shooting with the OVF is a no-go. The focus is all over the place. I can refocus on the same target and the focal point is different, sometimes wildly different, every time. And it isn't a Pentax issue, the Canon and Nikon versions had the same problem.

It's an otherwise great lens, I prefer it over a 17-50. I just wish I wasn't stuck with LV in order to get it to focus on anything.

**bobbotron** · 11-02-2021, 10:19 AM - **1 Like**

Originally posted by AfterPentax Mark II

It is a no brainer: Why support Sigma instead of the company that made that fabulous K-3 Mark III. They deserve some support, don't they? Go for that new 16-50!

Were funds unlimited I'd for sure get the 16-50... as is I can get a 18-35 for a third of the cost so it makes the decision harder.

**UncleVanya** · 11-02-2021, 10:20 AM

The 18-35 has a mixed reputation even outside of Pentax. The lens appears to be hard to focus at times. If you need f1.8 you don’t have any real options in that range other than a prime. The DA 20-40 is much smaller but also slower. The 16-50 is slower and has a larger range. The new Pentax DFA 21 looks nice but is not f1.8. The Sigma 20mm f1.8 has some pretty high sample variation and mediocre wide open performance: Sigma 20mm F1.8 EX Aspherical DG DF RF Lens Reviews - Sigma Lenses - Pentax Lens Review Database

The Sigma 24 f1.8 is a better focusing lens as is the Pentax FA 31 f1.8 or Sigma 35 f1.4 - so if a single prime can work you have options that may be better. If however the range is important and you need that fast f1.8 aperture (perhaps for optical effects) - only one option stands ready.

disconnekt · 11-02-2021, 10:21 AM - **1 Like**

Originally posted by Kozlok

I have the 18-35, and have used it on my K3III (but only about 250 shots total). It has maybe a bit worse keeper rate than my 16-85, but not unreasonably so. On my KS2, that lens worked well in single point focus mode, but not so well in multi-point mode. The K3III seems much more adept at managing the lens. Setting Autofocus to Auto multi-point mode and taking pictures of the grandkids worked out very well. Again, not a perfect keeper rate, but not bad.

I looked through a sequence of 11 shots at f1.8, and only 2 of those weren't focused on the eye. There were 2 more where it was just off the eye, but good enough at normal viewing magnification. 7 were basically perfectly focused on eyes in the shots. These were in good light. Indoors, my keeper rate was worse, maybe 20% were just terrible, and maybe another 20% where it focused on some random thing like a coffee cup. Again, not amazing, but workable.

At f2.8, my keeper rate seems to improve dramatically, with maybe 5% of shots just rubbish, and the rest better than adequate. By f5.6, it seems as good as any lens.

Here's a shot at f2.8 to whet your appetite.

Doggo is like "Ok Hooman I iz hurr, now where iz da treats?"

**UncleVanya** · 11-02-2021, 10:21 AM

Forgot this link:
Sigma 24mm F1.8 EX Aspherical DG DF Macro Lens Reviews - Sigma Lenses - Pentax Lens Review Database

**bobbotron** · 11-02-2021, 10:45 AM

Originally posted by UncleVanya

The 18-35 has a mixed reputation even outside of Pentax. The lens appears to be hard to focus at times. If you need f1.8 you don’t have any real options in that range other than a prime. The DA 20-40 is much smaller but also slower. The 16-50 is slower and has a larger range. The new Pentax DFA 21 looks nice but is not f1.8. The Sigma 20mm f1.8 has some pretty high sample variation and mediocre wide open performance: Sigma 20mm F1.8 EX Aspherical DG DF RF Lens Reviews - Sigma Lenses - Pentax Lens Review Database

The Sigma 24 f1.8 is a better focusing lens as is the Pentax FA 31 f1.8 or Sigma 35 f1.4 - so if a single prime can work you have options that may be better. If however the range is important and you need that fast f1.8 aperture (perhaps for optical effects) - only one option stands ready.

Yeah, I'm covered if I want to go with only a prime or two, but as much as I like primes (and man I do!) having a fast zoom would be much more useful when I get roped into covering events. I think the 16-50 covers my usage perfectly, but I can't afford it at the moment.

**UncleVanya** · 11-02-2021, 11:25 AM

Originally posted by bobbotron

Yeah, I'm covered if I want to go with only a prime or two, but as much as I like primes (and man I do!) having a fast zoom would be much more useful when I get roped into covering events. I think the 16-50 covers my usage perfectly, but I can't afford it at the moment.

Get the older version. It’s not a dog and there’s one in the marketplace for under $350 with working sdm if I remember accurately.

Also there are two 3rd party 17-50 f2.8 alternatives.

morenjavi · 11-02-2021, 12:10 PM

Hello.
I'm considering upgrading my K3-II and studying several options.
In particular, eye (or face) tracking is something that interests me a lot, it would make my job much easier.
My main workhorse lenses are the sigma 17-50mm and da 50-135mm (I know this is a slow lens). Does anybody tested such lenses with the K3-III? I would like to know if I will benefit from the new af, both in accuracy and eye tracking.
Maybe a new thread can be created sharing experiences with Pentax and 3rd party lenses, regarding the benefits of the new AF.
Regards.

angerdan · 11-02-2021, 12:17 PM

Originally posted by bobbotron

Bit of a dark horse given the mixed feedback on autofocus, have to imagine the better AF of the K3iii would help it out?

I'm looking for a fast zoom lens for covering indoor events, I'm thinking either this or the new 16-50 would be good.

Tince the AF motor is inside the lens, there's no change a better camera can archive faster AF with the Sigma 18-35mm.
If you're looking for an zoom lens with very fast AF, go for the new 16-50mm with DC motor

It's one of the fastest lenses for Pentax:
HD Pentax-DA* 16-50mm F2.8 ED PLM AW Reviews - DA Zoom Lenses - Pentax Lens Reviews & Lens Database

Originally posted by morenjavi

I would like to know if I will benefit from the new af, both in accuracy and eye tracking.
Maybe a new thread can be created sharing experiences with Pentax and 3rd party lenses, regarding the benefits of the new AF.

AF speed of all lenses with integrated ultrasonic motor keeps same speed.

AfterPentax Mark II · 11-02-2021, 12:24 PM

Originally posted by bobbotron

Were funds unlimited I'd for sure get the 16-50... as is I can get a 18-35 for a third of the cost so it makes the decision harder.

The Limited 20-40 might serve you well, certainly as you've got the K-3 III. 1.8 or 2.8 could be "complemented" by the better high(er) Iso performance of the K-3 III. The 20-40 is a gem once you get to know this little beast.

**bobbotron** · 11-02-2021, 01:47 PM

Originally posted by AfterPentax Mark II

The Limited 20-40 might serve you well, certainly as you've got the K-3 III. 1.8 or 2.8 could be "complemented" by the better high(er) Iso performance of the K-3 III. The 20-40 is a gem once you get to know this little beast.

The 20-40 is definitely a contender! I have the 18-135, but it's just a bit under powered in indoor settings.

AfterPentax Mark II · 11-02-2021, 02:17 PM - **1 Like**

Did you know that the 18-135 is very surprising lens? I bought it for my Samsung GX10 and with each new installment of a Pentax flagship I noticed the results got better. Beginning of this year I bought a KP to replace the K-3 II and the results with the 18-135 are even better than with the K-3 II. But the KP has a lot of the K-3 and some of K-1 genes combined. But with each impovement of the camera the 18-135 performed better, so my thought is that the 18-135 was ahead of the development of the Pentax camera's.

11-02-2021, 08:23 AM	#1
bobbotron Site Supporter Join Date: Jan 2015 Location: Ottawa, ON Photos: Gallery Posts: 3,349	Sigma 18-35mm on the K3iii? I'm really interested in this lens for the K3iii. Bit of a dark horse given the mixed feedback on autofocus, have to imagine the better AF of the K3iii would help it out? Anyone tried this combo? I'm looking for a fast zoom lens for covering indoor events, I'm thinking either this or the new 16-50 would be good.

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11-02-2021, 09:25 AM - 2 Likes	#2
Kozlok Pentaxian Join Date: Jun 2012 Location: Albuquerque Photos: Gallery Posts: 3,148	I have the 18-35, and have used it on my K3III (but only about 250 shots total). It has maybe a bit worse keeper rate than my 16-85, but not unreasonably so. On my KS2, that lens worked well in single point focus mode, but not so well in multi-point mode. The K3III seems much more adept at managing the lens. Setting Autofocus to Auto multi-point mode and taking pictures of the grandkids worked out very well. Again, not a perfect keeper rate, but not bad. I looked through a sequence of 11 shots at f1.8, and only 2 of those weren't focused on the eye. There were 2 more where it was just off the eye, but good enough at normal viewing magnification. 7 were basically perfectly focused on eyes in the shots. These were in good light. Indoors, my keeper rate was worse, maybe 20% were just terrible, and maybe another 20% where it focused on some random thing like a coffee cup. Again, not amazing, but workable. At f2.8, my keeper rate seems to improve dramatically, with maybe 5% of shots just rubbish, and the rest better than adequate. By f5.6, it seems as good as any lens. Here's a shot at f2.8 to whet your appetite.

11-02-2021, 09:54 AM - 1 Like	#3
AfterPentax Mark II Pentaxian Join Date: Mar 2021 Posts: 1,462	Originally posted by bobbotron I'm really interested in this lens for the K3iii. Bit of a dark horse given the mixed feedback on autofocus, have to imagine the better AF of the K3iii would help it out? Anyone tried this combo? I'm looking for a fast zoom lens for covering indoor events, I'm thinking either this or the new 16-50 would be good. It is a no brainer: Why support Sigma instead of the company that made that fabulous K-3 Mark III. They deserve some support, don't they? Go for that new 16-50!

11-02-2021, 10:03 AM	#4
abraswell Junior Member Join Date: Dec 2016 Location: Georgia Posts: 28	If you don't mind shooting in Live View 100% of the time is a good lens. Shooting with the OVF is a no-go. The focus is all over the place. I can refocus on the same target and the focal point is different, sometimes wildly different, every time. And it isn't a Pentax issue, the Canon and Nikon versions had the same problem. It's an otherwise great lens, I prefer it over a 17-50. I just wish I wasn't stuck with LV in order to get it to focus on anything.

11-02-2021, 10:19 AM - 1 Like	#5
bobbotron Site Supporter Join Date: Jan 2015 Location: Ottawa, ON Photos: Gallery Posts: 3,349 Original Poster	Originally posted by AfterPentax Mark II It is a no brainer: Why support Sigma instead of the company that made that fabulous K-3 Mark III. They deserve some support, don't they? Go for that new 16-50! Were funds unlimited I'd for sure get the 16-50... as is I can get a 18-35 for a third of the cost so it makes the decision harder.

11-02-2021, 10:20 AM	#6
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,409	The 18-35 has a mixed reputation even outside of Pentax. The lens appears to be hard to focus at times. If you need f1.8 you don’t have any real options in that range other than a prime. The DA 20-40 is much smaller but also slower. The 16-50 is slower and has a larger range. The new Pentax DFA 21 looks nice but is not f1.8. The Sigma 20mm f1.8 has some pretty high sample variation and mediocre wide open performance: Sigma 20mm F1.8 EX Aspherical DG DF RF Lens Reviews - Sigma Lenses - Pentax Lens Review Database The Sigma 24 f1.8 is a better focusing lens as is the Pentax FA 31 f1.8 or Sigma 35 f1.4 - so if a single prime can work you have options that may be better. If however the range is important and you need that fast f1.8 aperture (perhaps for optical effects) - only one option stands ready.

11-02-2021, 10:21 AM - 1 Like	#7
disconnekt Pentaxian Join Date: Oct 2011 Location: SoCal/I.E. Photos: Albums Posts: 1,699	Originally posted by Kozlok I have the 18-35, and have used it on my K3III (but only about 250 shots total). It has maybe a bit worse keeper rate than my 16-85, but not unreasonably so. On my KS2, that lens worked well in single point focus mode, but not so well in multi-point mode. The K3III seems much more adept at managing the lens. Setting Autofocus to Auto multi-point mode and taking pictures of the grandkids worked out very well. Again, not a perfect keeper rate, but not bad. I looked through a sequence of 11 shots at f1.8, and only 2 of those weren't focused on the eye. There were 2 more where it was just off the eye, but good enough at normal viewing magnification. 7 were basically perfectly focused on eyes in the shots. These were in good light. Indoors, my keeper rate was worse, maybe 20% were just terrible, and maybe another 20% where it focused on some random thing like a coffee cup. Again, not amazing, but workable. At f2.8, my keeper rate seems to improve dramatically, with maybe 5% of shots just rubbish, and the rest better than adequate. By f5.6, it seems as good as any lens. Here's a shot at f2.8 to whet your appetite. Doggo is like "Ok Hooman I iz hurr, now where iz da treats?"

11-02-2021, 10:21 AM	#8
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,409	Forgot this link: Sigma 24mm F1.8 EX Aspherical DG DF Macro Lens Reviews - Sigma Lenses - Pentax Lens Review Database

11-02-2021, 10:45 AM	#9
bobbotron Site Supporter Join Date: Jan 2015 Location: Ottawa, ON Photos: Gallery Posts: 3,349 Original Poster	Originally posted by UncleVanya The 18-35 has a mixed reputation even outside of Pentax. The lens appears to be hard to focus at times. If you need f1.8 you don’t have any real options in that range other than a prime. The DA 20-40 is much smaller but also slower. The 16-50 is slower and has a larger range. The new Pentax DFA 21 looks nice but is not f1.8. The Sigma 20mm f1.8 has some pretty high sample variation and mediocre wide open performance: Sigma 20mm F1.8 EX Aspherical DG DF RF Lens Reviews - Sigma Lenses - Pentax Lens Review Database The Sigma 24 f1.8 is a better focusing lens as is the Pentax FA 31 f1.8 or Sigma 35 f1.4 - so if a single prime can work you have options that may be better. If however the range is important and you need that fast f1.8 aperture (perhaps for optical effects) - only one option stands ready. Yeah, I'm covered if I want to go with only a prime or two, but as much as I like primes (and man I do!) having a fast zoom would be much more useful when I get roped into covering events. I think the 16-50 covers my usage perfectly, but I can't afford it at the moment.

11-02-2021, 11:25 AM	#10
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,409	Originally posted by bobbotron Yeah, I'm covered if I want to go with only a prime or two, but as much as I like primes (and man I do!) having a fast zoom would be much more useful when I get roped into covering events. I think the 16-50 covers my usage perfectly, but I can't afford it at the moment. Get the older version. It’s not a dog and there’s one in the marketplace for under $350 with working sdm if I remember accurately. Also there are two 3rd party 17-50 f2.8 alternatives.

11-02-2021, 12:10 PM	#11
morenjavi Pentaxian Join Date: Jul 2016 Posts: 589	Hello. I'm considering upgrading my K3-II and studying several options. In particular, eye (or face) tracking is something that interests me a lot, it would make my job much easier. My main workhorse lenses are the sigma 17-50mm and da 50-135mm (I know this is a slow lens). Does anybody tested such lenses with the K3-III? I would like to know if I will benefit from the new af, both in accuracy and eye tracking. Maybe a new thread can be created sharing experiences with Pentax and 3rd party lenses, regarding the benefits of the new AF. Regards.

11-02-2021, 12:17 PM	#12
angerdan Pentaxian Join Date: Feb 2015 Photos: Gallery \| Albums Posts: 2,639	Originally posted by bobbotron Bit of a dark horse given the mixed feedback on autofocus, have to imagine the better AF of the K3iii would help it out? I'm looking for a fast zoom lens for covering indoor events, I'm thinking either this or the new 16-50 would be good. Tince the AF motor is inside the lens, there's no change a better camera can archive faster AF with the Sigma 18-35mm. If you're looking for an zoom lens with very fast AF, go for the new 16-50mm with DC motor It's one of the fastest lenses for Pentax: HD Pentax-DA* 16-50mm F2.8 ED PLM AW Reviews - DA Zoom Lenses - Pentax Lens Reviews & Lens Database Originally posted by morenjavi I would like to know if I will benefit from the new af, both in accuracy and eye tracking. Maybe a new thread can be created sharing experiences with Pentax and 3rd party lenses, regarding the benefits of the new AF. AF speed of all lenses with integrated ultrasonic motor keeps same speed.

11-02-2021, 12:24 PM	#13
AfterPentax Mark II Pentaxian Join Date: Mar 2021 Posts: 1,462	Originally posted by bobbotron Were funds unlimited I'd for sure get the 16-50... as is I can get a 18-35 for a third of the cost so it makes the decision harder. The Limited 20-40 might serve you well, certainly as you've got the K-3 III. 1.8 or 2.8 could be "complemented" by the better high(er) Iso performance of the K-3 III. The 20-40 is a gem once you get to know this little beast.

11-02-2021, 01:47 PM	#14
bobbotron Site Supporter Join Date: Jan 2015 Location: Ottawa, ON Photos: Gallery Posts: 3,349 Original Poster	Originally posted by AfterPentax Mark II The Limited 20-40 might serve you well, certainly as you've got the K-3 III. 1.8 or 2.8 could be "complemented" by the better high(er) Iso performance of the K-3 III. The 20-40 is a gem once you get to know this little beast. The 20-40 is definitely a contender! I have the 18-135, but it's just a bit under powered in indoor settings.

11-02-2021, 02:17 PM - 1 Like	#15
AfterPentax Mark II Pentaxian Join Date: Mar 2021 Posts: 1,462	Did you know that the 18-135 is very surprising lens? I bought it for my Samsung GX10 and with each new installment of a Pentax flagship I noticed the results got better. Beginning of this year I bought a KP to replace the K-3 II and the results with the 18-135 are even better than with the K-3 II. But the KP has a lot of the K-3 and some of K-1 genes combined. But with each impovement of the camera the 18-135 performed better, so my thought is that the 18-135 was ahead of the development of the Pentax camera's.