SIGMA 10-20mm CLUB

jgnfld · 06-27-2018, 03:55 AM

Originally posted by LensBeginner

Subject-wise, that's almost a given, but I don't think it depends on the APS-C sensor tout-court, rather on pixel density.
I was talking optically, since my copy's plane of focus is not perfectly planar (or approximately, or at least uniformely curved), rather is a little bit deformed so the far right side tends to focus a bit closer than the rest of the image.
This is only evident at long distances, thus my remark on my particular copy of this lens.

Re. sensor size, I have seen pleasing UWA focal length pics done on a 645, for example, that I know would not look the same with my K-70. As you say, other issues--including individual lens foibles--remain, however

LensBeginner · 06-27-2018, 04:17 AM

Originally posted by jgnfld

Re. sensor size, I have seen pleasing UWA focal length pics done on a 645, for example, that I know would not look the same with my K-70. As you say, other issues--including individual lens foibles--remain, however

Well, a 645Z has a pixel pitch of 5.32 µm, while a K-5 (and as a consequence the K-01 and the K-30/50) has a pixel pitch of 4.77 µm, that is about the same.
But, of course, the total number of pixel is completely different, and that shows when taking into account the same viewing size.

I too have had the impression of lack of detail and resolving power, especially when shooting at 10mm.
Then I tried shooting the same scene with the 18-55 at 18mm, and I could make out finer details with the Sigma at 10mm than I could with the kit at 18mm.
So, as you say, it's more "detail compression" than resolving power... we're probably used to see certain things represented with a minimum number of pixels, and when they aren't (because they're "smaller"), we perceive a lack of detail.

skierd · 07-01-2018, 10:47 PM - **1 Like**

**Mikesul** · 07-04-2018, 01:20 PM

This has always been one of my favorite wide angles on Pentax cameras

LensBeginner · 07-06-2018, 01:17 PM - **2 Likes**

Sigma 10-20 at 20mm
Full gallery here.

B1_4 by Paolo Del Lungo, su Flickr

Thagomizer · 07-16-2018, 03:50 PM - **1 Like**

A few months ago I posted photos of preparations for removing a bridge in my hometown of London, Ontario, Canada. Well, they're getting ready to start putting Blackfriars Bridge back.

Here are some panoramic views made up of a bunch of shots.

**Mikesul** · 07-19-2018, 09:24 AM - **1 Like**

Originally posted by LensBeginner

Sigma 10-20 at 20mm

Great and unusual view of Florence. Love the color.

catwalk · 07-19-2018, 11:33 PM - **5 Likes**

Just got the F3.5 model today and on its maiden voyage I came across this amazing cloud formation during a sunset. What a lens!

Shot at 10mm.

Shot at 18mm.

**Tamia** · 07-20-2018, 08:45 AM

Originally posted by catwalk

Just got the F3.5 model today and on its maiden voyage I came across this amazing cloud formation during a sunset. What a lens!

Shot at 10mm.

Shot at 18mm.

What a spectacular set of photos! Impressive cloud formation, and the silhouette works really well here. Do this cloud and colors have anything to do with that Arizona dust storm I saw mentioned in the headlines?

catwalk · 07-20-2018, 11:01 AM

Originally posted by Tamia

Do this cloud and colors have anything to do with that Arizona dust storm I saw mentioned in the headlines?

Thanks! No I am much further south than the dust storm, we rarely get them up in the mountains here. We have daily thunderstorms this time of year, and I always see amazing photo opportunities because of it.

Sagitta · 07-21-2018, 01:51 PM - **7 Likes**

Not sure if I shared some of these or not... if so, apologies for the duplicates.

swanlefitte · 07-27-2018, 02:32 PM - **1 Like**

There is a lizard in the center directly above the V pointing right at me. Its just a dark spot really in the picture.

Thagomizer · 08-07-2018, 08:12 AM - **5 Likes**

A fleeting trick of the light.

takis63 · 08-13-2018, 11:25 AM - **1 Like**

Stargazing - Mt.Parnon Greece
The bright object to the left above the telescope is planet Mars.

Andep · 08-16-2018, 10:53 AM - **5 Likes**

10-20mm/f3.5, 10mm, f/8.0, Pentax K3-ii

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06-27-2018, 03:55 AM	#3751
jgnfld Moderator Loyal Site Supporter Join Date: Feb 2015 Location: Avalon Peninsula, Newfoundland Photos: Gallery \| Albums Posts: 1,789	Originally posted by LensBeginner Subject-wise, that's almost a given, but I don't think it depends on the APS-C sensor tout-court, rather on pixel density. I was talking optically, since my copy's plane of focus is not perfectly planar (or approximately, or at least uniformely curved), rather is a little bit deformed so the far right side tends to focus a bit closer than the rest of the image. This is only evident at long distances, thus my remark on my particular copy of this lens. Re. sensor size, I have seen pleasing UWA focal length pics done on a 645, for example, that I know would not look the same with my K-70. As you say, other issues--including individual lens foibles--remain, however

06-27-2018, 04:17 AM	#3752
LensBeginner Veteran Member Join Date: Sep 2014 Photos: Albums Posts: 4,696	Originally posted by jgnfld Re. sensor size, I have seen pleasing UWA focal length pics done on a 645, for example, that I know would not look the same with my K-70. As you say, other issues--including individual lens foibles--remain, however Well, a 645Z has a pixel pitch of 5.32 µm, while a K-5 (and as a consequence the K-01 and the K-30/50) has a pixel pitch of 4.77 µm, that is about the same. But, of course, the total number of pixel is completely different, and that shows when taking into account the same viewing size. I too have had the impression of lack of detail and resolving power, especially when shooting at 10mm. Then I tried shooting the same scene with the 18-55 at 18mm, and I could make out finer details with the Sigma at 10mm than I could with the kit at 18mm. So, as you say, it's more "detail compression" than resolving power... we're probably used to see certain things represented with a minimum number of pixels, and when they aren't (because they're "smaller"), we perceive a lack of detail.

07-01-2018, 10:47 PM - 1 Like	#3753
skierd Veteran Member Join Date: Mar 2011 Location: Fairbanks, AK Photos: Gallery Posts: 1,472

07-04-2018, 01:20 PM	#3754
Mikesul Loyal Site Supporter Join Date: Sep 2009 Location: Phoenix, AZ Posts: 7,594	This has always been one of my favorite wide angles on Pentax cameras

07-06-2018, 01:17 PM - 2 Likes	#3755
LensBeginner Veteran Member Join Date: Sep 2014 Photos: Albums Posts: 4,696	Sigma 10-20 at 20mm Full gallery here. B1_4 by Paolo Del Lungo, su Flickr

07-16-2018, 03:50 PM - 1 Like	#3756
Thagomizer Pentaxian Join Date: Jun 2014 Location: London Ontario Posts: 2,068	A few months ago I posted photos of preparations for removing a bridge in my hometown of London, Ontario, Canada. Well, they're getting ready to start putting Blackfriars Bridge back. Here are some panoramic views made up of a bunch of shots.

07-19-2018, 09:24 AM - 1 Like	#3757
Mikesul Loyal Site Supporter Join Date: Sep 2009 Location: Phoenix, AZ Posts: 7,594	Originally posted by LensBeginner Sigma 10-20 at 20mm Great and unusual view of Florence. Love the color.

07-19-2018, 11:33 PM - 5 Likes	#3758
catwalk Junior Member Join Date: Jul 2018 Location: Arizona Photos: Gallery Posts: 48	Just got the F3.5 model today and on its maiden voyage I came across this amazing cloud formation during a sunset. What a lens! Shot at 10mm. Shot at 18mm.

07-20-2018, 08:45 AM	#3759
Tamia Site Supporter Join Date: Dec 2009 Location: Here, there, and everywhere. Photos: Gallery \| Albums Posts: 4,384	Originally posted by catwalk Just got the F3.5 model today and on its maiden voyage I came across this amazing cloud formation during a sunset. What a lens! Shot at 10mm. Shot at 18mm. What a spectacular set of photos! Impressive cloud formation, and the silhouette works really well here. Do this cloud and colors have anything to do with that Arizona dust storm I saw mentioned in the headlines?

07-20-2018, 11:01 AM	#3760
catwalk Junior Member Join Date: Jul 2018 Location: Arizona Photos: Gallery Posts: 48	Originally posted by Tamia Do this cloud and colors have anything to do with that Arizona dust storm I saw mentioned in the headlines? Thanks! No I am much further south than the dust storm, we rarely get them up in the mountains here. We have daily thunderstorms this time of year, and I always see amazing photo opportunities because of it.

07-21-2018, 01:51 PM - 7 Likes	#3761
Sagitta Veteran Member Join Date: Feb 2011 Location: Maine Photos: Gallery Posts: 3,081	Not sure if I shared some of these or not... if so, apologies for the duplicates.

07-27-2018, 02:32 PM - 1 Like	#3762
swanlefitte Pentaxian Join Date: May 2015 Location: Minneapolis Photos: Gallery Posts: 4,068	There is a lizard in the center directly above the V pointing right at me. Its just a dark spot really in the picture.

08-07-2018, 08:12 AM - 5 Likes	#3763
Thagomizer Pentaxian Join Date: Jun 2014 Location: London Ontario Posts: 2,068	A fleeting trick of the light.

08-16-2018, 10:53 AM - 5 Likes	#3765
Andep Junior Member Join Date: Jun 2013 Posts: 49	10-20mm/f3.5, 10mm, f/8.0, Pentax K3-ii