SIGMA 8-16mm CLUB

QCdude · 10-07-2014, 08:08 PM - **3 Likes**

f8, 1/125, iso100 8mm K-5 IIs

civiletti · 10-07-2014, 11:34 PM

Originally posted by Digitalis

Wideangle lenses need to be stopped down - it's the only way to effectively deal with field curvature and astigmatism that is inevitably in the corners. Even with the Sigma 8-16mm f/4.5-5.6 I will regularly stop down to f/11 so that the lens is sharp across the entire frame, diffraction be damned. Using a super wide angle lens you aren't going to get shallow Dof effects like you can with a 50mm f/1.4 lens - so wider apertures aren't all that important.

Here is the test from PhotoZone on a Canon ASP-C. It shows maximum corner resolution at f8 at 8/12/16mm. For maximum center resolution wide open is best. So, it seems that diffraction more than balances any gain from lower aberrations at small apertures.

**Digitalis** · 10-08-2014, 01:23 AM

I will also point out that the Canon DSLR does have not only lower resolution but also an AA filter so performance will be somewhat better on a camera like the K5IIs. Also the photozone tests to not take field curvature into account - just about every ultra wide angle lens designed for smaller formats have it.

civiletti · 10-08-2014, 10:33 PM

Originally posted by Digitalis

I will also point out that the Canon DSLR does have not only lower resolution but also an AA filter so performance will be somewhat better on a camera like the K5IIs. Also the photozone tests to not take field curvature into account - just about every ultra wide angle lens designed for smaller formats have it.

Higher sensor resolution increases the loss from diffraction as well. I doubt that will move optimal aperture much. When not photographing subjects lying in a plane perpendicular to lens access, the effect of field curvature varies. In some conditions it will increase resolution in the corners.

**Digitalis** · 10-08-2014, 11:27 PM - **1 Like**

Originally posted by civiletti

the effect of field curvature varies. In some conditions it will increase resolution in the corners.

Providing you know how to take advantage of it and the geometry of the scene you are photographing conforms to it.

Transit · 10-11-2014, 03:05 AM

I got the wattle down

huge crop

8mm f6.3

**dadipentak** · 10-11-2014, 05:50 AM

Originally posted by Transit

huge crop

Effective!

richardwong · 10-11-2014, 08:28 AM

Nice silhouette shot.

QCdude · 10-11-2014, 04:21 PM

and no flare

Transit · 10-11-2014, 10:18 PM

Thanks chaps

no flare and no sharpening, so likeing the K-5iis

**Mikesul** · 10-12-2014, 07:03 AM

K3 Sigma 8-16 at 8

**Digitalis** · 10-26-2014, 04:41 AM - **2 Likes**

Pentax K5IIS - Sigma 8-16mm f/4.5-5.6 @ 12mm f/11 30s ISO 80

**wtlwdwgn** · 10-26-2014, 08:40 AM

Nice shot!

richardwong · 10-26-2014, 11:10 PM

Very nice Digitalis.

**Mikesul** · 10-27-2014, 05:36 AM

Great picture, Digitalis! Did you use a lightning detector?

10-08-2014, 11:27 PM - 1 Like	#605
Digitalis Site Supporter Join Date: Mar 2009 Location: Melbourne, Victoria Photos: Gallery Posts: 11,694	Originally posted by civiletti the effect of field curvature varies. In some conditions it will increase resolution in the corners. Providing you know how to take advantage of it and the geometry of the scene you are photographing conforms to it. Last edited by Digitalis; 10-11-2014 at 03:31 AM.

10-11-2014, 03:05 AM	#606
Transit Pentaxian Join Date: Aug 2007 Location: Whanganui NZ Photos: Gallery \| Albums Posts: 4,624	I got the wattle down huge crop 8mm f6.3 Last edited by Transit; 10-11-2014 at 03:34 AM.

10-12-2014, 07:03 AM	#611
Mikesul Loyal Site Supporter Join Date: Sep 2009 Location: Phoenix, AZ Posts: 7,594	House Shapes K3 Sigma 8-16 at 8

10-27-2014, 05:36 AM	#615
Mikesul Loyal Site Supporter Join Date: Sep 2009 Location: Phoenix, AZ Posts: 7,594	Sigma 8-16 lightning Great picture, Digitalis! Did you use a lightning detector?

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Sigma 8-16mm Review	viking79	Pentax SLR Lens Discussion	14	02-15-2018 04:56 AM
What about Sigma 8-16mm??	mikiresty	Pentax SLR Lens Discussion	5	06-19-2010 04:00 AM
When does the 8-16mm sigma come out?	WerTicus	Pentax SLR Lens Discussion	1	05-16-2010 01:13 PM
Sigma 8-16mm Preorder	Nerdold Nerdith	Pentax SLR Lens Discussion	12	04-20-2010 05:54 AM
For Sale - Sold: Sigma 180mm f3.5 macro, Sigma 16mm f2.8 Filtermatic Fisheye, K20D, K100D Super	jfirneno	Sold Items	16	02-05-2010 06:46 AM

10-07-2014, 08:08 PM - 3 Likes	#601
QCdude Forum Member Join Date: Jul 2013 Photos: Gallery Posts: 87	f8, 1/125, iso100 8mm K-5 IIs

10-07-2014, 11:34 PM	#602
civiletti Pentaxian Join Date: Jul 2010 Location: Oregon Photos: Albums Posts: 1,435	Originally posted by Digitalis Wideangle lenses need to be stopped down - it's the only way to effectively deal with field curvature and astigmatism that is inevitably in the corners. Even with the Sigma 8-16mm f/4.5-5.6 I will regularly stop down to f/11 so that the lens is sharp across the entire frame, diffraction be damned. Using a super wide angle lens you aren't going to get shallow Dof effects like you can with a 50mm f/1.4 lens - so wider apertures aren't all that important. Here is the test from PhotoZone on a Canon ASP-C. It shows maximum corner resolution at f8 at 8/12/16mm. For maximum center resolution wide open is best. So, it seems that diffraction more than balances any gain from lower aberrations at small apertures.

10-08-2014, 01:23 AM	#603
Digitalis Site Supporter Join Date: Mar 2009 Location: Melbourne, Victoria Photos: Gallery Posts: 11,694	I will also point out that the Canon DSLR does have not only lower resolution but also an AA filter so performance will be somewhat better on a camera like the K5IIs. Also the photozone tests to not take field curvature into account - just about every ultra wide angle lens designed for smaller formats have it.

10-08-2014, 10:33 PM	#604
civiletti Pentaxian Join Date: Jul 2010 Location: Oregon Photos: Albums Posts: 1,435	Originally posted by Digitalis I will also point out that the Canon DSLR does have not only lower resolution but also an AA filter so performance will be somewhat better on a camera like the K5IIs. Also the photozone tests to not take field curvature into account - just about every ultra wide angle lens designed for smaller formats have it. Higher sensor resolution increases the loss from diffraction as well. I doubt that will move optimal aperture much. When not photographing subjects lying in a plane perpendicular to lens access, the effect of field curvature varies. In some conditions it will increase resolution in the corners.

10-11-2014, 05:50 AM	#607
dadipentak Site Supporter Join Date: Jul 2008 Location: Baltimore, Maryland Photos: Gallery Posts: 11,590	Originally posted by Transit huge crop Effective!

10-11-2014, 08:28 AM	#608
richardwong Veteran Member Join Date: Nov 2012 Location: Vancouver, BC Photos: Gallery \| Albums Posts: 671	Nice silhouette shot.

10-11-2014, 04:21 PM	#609
QCdude Forum Member Join Date: Jul 2013 Photos: Gallery Posts: 87	and no flare

10-11-2014, 10:18 PM	#610
Transit Pentaxian Join Date: Aug 2007 Location: Whanganui NZ Photos: Gallery \| Albums Posts: 4,624	Thanks chaps no flare and no sharpening, so likeing the K-5iis

10-26-2014, 04:41 AM - 2 Likes	#612
Digitalis Site Supporter Join Date: Mar 2009 Location: Melbourne, Victoria Photos: Gallery Posts: 11,694	Pentax K5IIS - Sigma 8-16mm f/4.5-5.6 @ 12mm f/11 30s ISO 80

10-26-2014, 08:40 AM	#613
wtlwdwgn Site Supporter Join Date: Jan 2007 Location: Billings, MT Photos: Gallery \| Albums Posts: 13,838	Nice shot!

10-26-2014, 11:10 PM	#614
richardwong Veteran Member Join Date: Nov 2012 Location: Vancouver, BC Photos: Gallery \| Albums Posts: 671	Very nice Digitalis.