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06-07-2011, 04:11 PM   #16
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The 8-16mm seems the most impressive to me, check out lenstip's review! I'm almost tempted to upgrade my sigma 10-20, which I find an excellent lens by the way.

06-07-2011, 04:12 PM   #17
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Rectilinear or fisheye? Explain the difference please.
06-07-2011, 04:20 PM   #18
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Simply put - rectilinear lenses don't intend to distort the image, whereas fish-eye lenses intentionally distort the image to create a very wide-angled perspective, as a fish would see through its eyes.

A bit of research, and the answer is clear:
Field of View - Rectilinear and Fisheye Lenses
ARRI Group: What is 'Rectilinear,' What is a 'Fisheye'?
06-07-2011, 05:03 PM   #19
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Very interesting. Thanks. I think it would be nice to own both types.

06-07-2011, 08:17 PM   #20
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Super-duper-wide lenses always distort. Rectilinears stretch the margins; fisheyes bend the margins. These distortions result because a lens tries to project a round world onto a flat frame. A fisheye lens actually projects a more accurate image, but we don't LIKE that accuracy!

You needn't go ultrawide to see rectilinear distortion. I see it with 24mm lenses on an APS-C frame, and (less) with 35mm lenses on a FF camera. I *suspect* that lenses wider than the 'normal' focal length (30mm on my K20D, 43mm on my K1000) will give such distortion.
06-09-2011, 05:46 AM   #21
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Some of these lenses are very spendy. I highly recommend renting for a week or some event to decide whether you like them. I rented the 10-17 fisheye, and then bought one. I rented the 21mm limited and liked it but don't think I'd use it frequently enough to purchase. The 16-45 works well for me, but I'm tempted to try the 12-24 or Sigma's 10-20.

I've rented from cameralensrentals.com numerous times and find it economical.
06-09-2011, 01:39 PM - 1 Like   #22
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QuoteOriginally posted by RioRico Quote
Super-duper-wide lenses always distort.
That's right. As an example, consider this photo from the DA 12-24 at 12mm. Notice how the trees begin to bend toward the borders of the image:



How noticeable the distortion is depends on the subject. It's less noticeable, though still apparent, in this image, also taken at 12mm:



I wouldn't get too caught up in such issues as distortion, CA problems, or even resolution when choosing an UWA zoom lens. Get the best lens that you can afford that fits your specific needs.
06-09-2011, 06:31 PM   #23
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Those are beautiful pics, the trees really do show the distortion. I wonder how they'd look at 8mm.

06-09-2011, 06:33 PM   #24
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QuoteOriginally posted by northcoastgreg Quote
That's right. As an example, consider this photo from the DA 12-24 at 12mm. Notice how the trees begin to bend toward the borders of the image:



How noticeable the distortion is depends on the subject. It's less noticeable, though still apparent, in this image, also taken at 12mm:



I wouldn't get too caught up in such issues as distortion, CA problems, or even resolution when choosing an UWA zoom lens. Get the best lens that you can afford that fits your specific needs.
Was a polarizing filter used on these shots? I read the 8-16 won't take filters.
06-10-2011, 05:58 PM   #25
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QuoteOriginally posted by kenafein Quote
Was a polarizing filter used on these shots? I read the 8-16 won't take filters.
You're right that the Sigma 8-16 won't take filters. That's a problem if you want to use ND grad filters with it (you'd have to hold square versions by hand), but it's not an issue with polarizers, because that lens is just too wide to make use of polarizers. Of the two shots I posted, only the lower one of the bridge used a polarizer, and that mainly because it was cloudy and there was only a small portion of sky that would be affected. Normally, with ultra wide angle, you can't use a polarizer because you'll get uneven coverage. A polarizer would have ruined that lake shot (with Mount Lassen in the background) because the sky would've been darkened only partially, and the uneven coverage would've looked unattractive. In any case, one advantage that the DA 12-24 enjoys over the other UWA zooms is that you really don't need a polarizer to darken the skies. The outstanding color rendition of the lens produces dark rich blue skies without a polarizer. It produces some of the best blues I've ever seen from a lens (and some of the richest, darkest greens). I suspect that Pentax set out to specially optimize the lens for landscape use.
06-10-2011, 06:10 PM   #26
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Forgive my nubness thought you could use a linear polarizer for skies. You are really selling the 12-24. Your pics look great. I also made the mistake at looking at the 15 mm limited thread. Made me want one so bad, but your shots show I can get quality and zoom with practice.
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