there’s no simple answer to this question. lenses are designed differently:
for example, a RECTILINEAR wide angle lens distorts a lot less than a FISH-EYE lens, which distorts a whole lot more. A 15mm rectilinear, therefore, distorts less than a 16mm fisheye, even though the one is wider than the other.
then you get into RETROFOCUS vs. NON-RETROFOCUS designs for wide angle lens. most modern wide-angle lenses for SLR cameras are retrofocus so that the rear lens element does not need to be too close to the focal plane; no need for mirror lock-up, etc. however, non-retrofocus designs, such as the old Nikkor 21mm f/4 or Canon 19mm f/3.5, will distort less than their retrofocus cousins. but they will vignette. also modern retrofocus lenses, at least the high end ones, have been corrected more.
really expensive wide-angle lenses should distort less than their cheap alternatives. The Leica 28mm f/2.0 Aspherical in M mount, for example, distorts so little that you might think that the photos shot with it were made with a 35mm or even 50mm lens.
with digital and ultra-wide lenses, you have to worry about more than just distortion. because of the angle at which light hits the sensor, wider lenses don’t perform well on digital. the wider you get, the more fringing, halo-ing, and other such image degrading factors you’re going to get. that’s why some companies have made specific “digital” lenses supposedly corrected and optimized to reduce these problems. it’s also the reason why more digital cameras aren’t “full frame.”
then there’s technical vs. apparent distortion. Even a 35mm lens, barely even considered a wide-angle these days, distorts more than a normal 50mm. but we’re so used to seeing photos made with 35mm lenses that we don’t consider that level of distortion to be “too much.” And, the same is true with a good 28mm. So it’s fair to say that apparent or noticeable distortion starts with 25mm and 24mm lenses. that would be 16mm or 17mm for digital cameras with 1.5x crop factor.
20mm lenses, which become 30mm on 1.5x cropped digitals, are probably the widest you can go without it beginning to look like “wide-angle.”
31 Aug 2006 08:08
| New York, NY,