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03-24-2010, 10:44 AM   #1
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16-50 vs others

Hi,
Recently I took a few snapshots of kids at a party with 16-50. On some of them there were faces at the edges of the pictures who looked really fat. According to EXIF, the FL of those shots was 16-18mm. I understand it's a result of barrel distortion.
My questions are:
Do other UW lenses, e.g. 12-24, da15, produce the same level of distortion at, say, 15mm?
Are there any applications that can correct it?
Thank you very much,

03-24-2010, 11:25 AM   #2
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It is NOT barrel distortion. It is a form of perspective distortion caused by short focal length. It will happen with ALL short focal length.
03-24-2010, 11:47 AM   #3
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QuoteOriginally posted by sinus007 Quote
Hi,
Recently I took a few snapshots of kids at a party with 16-50. On some of them there were faces at the edges of the pictures who looked really fat. According to EXIF, the FL of those shots was 16-18mm. I understand it's a result of barrel distortion.
My questions are:
Do other UW lenses, e.g. 12-24, da15, produce the same level of distortion at, say, 15mm?
Are there any applications that can correct it?
Thank you very much,
It is not barrel distortion as Yves pointed out.
Some UW lenses do have a lot of distortion, like fish eye lenses.
Take the 10-17mm lens for instance.

A few 10mm examples:







- Bert
03-24-2010, 12:22 PM   #4
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QuoteOriginally posted by sinus007 Quote
Hi,
Recently I took a few snapshots of kids at a party with 16-50. On some of them there were faces at the edges of the pictures who looked really fat. According to EXIF, the FL of those shots was 16-18mm. I understand it's a result of barrel distortion.
My questions are:
Do other UW lenses, e.g. 12-24, da15, produce the same level of distortion at, say, 15mm?
Are there any applications that can correct it?
Thank you very much,
Relative size is proportional to the distance from the camera. Something 2x as far from the camera will appear to be 1/2 the size. So, when you are very close with a wide angle, the relative size drops off quickly. Just the opposite with a telephoto, which tends to make things the same size because they are relatively the same distance away.

03-24-2010, 01:08 PM   #5
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Original Poster
Thanks guys.
Are there any measures to minimize this distortion?
03-24-2010, 01:14 PM   #6
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Move your subject more to the middle of the frame or use longer FLs.
In the center even fish-eye lenses are almost distortion-free.
03-24-2010, 02:33 PM   #7
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Putting people more in the middle is best. You can make some correction using Photoshop's skew tool, but that will mean you'll lose some off the sides (same as if you were correcting perspective errors).
03-27-2010, 07:30 AM   #8
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QuoteOriginally posted by flyer Quote
It is NOT barrel distortion. It is a form of perspective distortion caused by short focal length. It will happen with ALL short focal length.
The 16-50mm does have pretty severe barrel distortion at the wide end, so I'd say it's a combination of barrel and perspective distortion.

In-camera lens correction with a K-x or K-7 will remove the barrel distortion or take it out with software like PT Lens. Nothing can be done about the perspective distortion after the fact.

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