PentaxForums.com - View Single Post - Bokeh, Specular Highlights, Guess The Lens

Jonas B · 01-18-2008, 05:54 AM

Originally Posted by creampuff

Jonas, thanks for the images. Very informative. Both the Sigma and Pentax have aspherical elements and it does seem that both have concentric circle oof points from you pictures. Obviously the lens construction and aperture blades have a part to play too.
BTW the second image (FA35mm?) is so much nicer

Hi,

Yes, they are both sporting aspherical elements. The concentric circles are more pronounced with the Sigma lens, very faint with the Pentax. And sure, the second image is more "eyecandy" than the Sigma (the top one).

The good thing with the Sigma is that the bokeh is neutral where the FA35 shows bright rings. Thin smaller bright spots in the background and the Sigma will make make much better than the Pentax in this case. Then again, when these bright spots are near the edges/corners they get a weird shape with the Sigma, and much less (and softer) with the FA35.

What are the designers thinking of?

01-18-2008, 05:54 AM	#96
Jonas B Pentaxian Location: Göteborg, Sweden Gallery Photos: 0 Posts: 810	Originally Posted by creampuff Jonas, thanks for the images. Very informative. Both the Sigma and Pentax have aspherical elements and it does seem that both have concentric circle oof points from you pictures. Obviously the lens construction and aperture blades have a part to play too. BTW the second image (FA35mm?) is so much nicer Hi, Yes, they are both sporting aspherical elements. The concentric circles are more pronounced with the Sigma lens, very faint with the Pentax. And sure, the second image is more "eyecandy" than the Sigma (the top one). The good thing with the Sigma is that the bokeh is neutral where the FA35 shows bright rings. Thin smaller bright spots in the background and the Sigma will make make much better than the Pentax in this case. Then again, when these bright spots are near the edges/corners they get a weird shape with the Sigma, and much less (and softer) with the FA35. What are the designers thinking of?