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Old Aug 15, 2012, 4:49 PM   #1
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Default How wide without fisheye?

I'm just curious for future daydreaming: what is the widest wide angle lens that will not produce a fisheye distortion? I personally don't care for the effect, but I'm not sure of the physics. I'm using a crop sensor 60D.
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Old Aug 15, 2012, 6:11 PM   #2
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Fisheye lenses produce an accurate image of a very wide angle of view. Conventional lenses try to produce a rectilinear image, which is not an accurate representation of what the camera sees. Some conventional lenses do this better than others. In the ones that don't do it very well, it's called barrel distortion, which is what a fisheye lens has in spades.

For instance, Canon's 14mm f/2.8 II USM is very nearly perfectly rectilinear, but Canons original 14mm f/2.8 USM slightly over corrected, producing what's known as pincushion distortion (the opposite of barrel distortion.). But compare that to Canon's 15mm f/2.8 lens which is actually a fisheye lens.

There is no dividing line between where a lens is a "Fisheye" and where it's not. If it's labeled "Fisheye", the manufacturer has made no attempt to design the lens so it would produce a rectilinear image. If it's not labeled "Fisheye", the the manufacturer has attempted to design the lens so it would produce a rectilinear image. The degree of success they had is shown in test resutls like those on SLRGear.com and PhotoZone.de.
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Old Aug 15, 2012, 8:31 PM   #3
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Thanks for the explanation. I guess I kind of figured there was more to it than a specific focal length dividing fisheye from rectilinear. This is good food for thought.
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Old Aug 16, 2012, 9:45 AM   #4
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The widest rectilinear wide angle for crop sensor DSLRs is the Sigma 8-16mm f/4.5-5.6 DC HSM http://www.sigmaphoto.com/shop/8-16m...6-dc-hsm-sigma which is available in several popular mounts.
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