Archived posting to the Leica Users Group, 1998/02/04
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Danny, In the interest of brevity, I'll keep this to the main points: 1) In an ideal (fully corrected) lens, used on flat film, perspective rendition is the same for all lenses, no matter the construction type and focal length. As the field of view increases, the corners of the image relate less and less to our usual visual interpretation, and we call that perspective distortion. 2) Linear distortion is a direct function of a variation in magnification across the image field. A true rectilinear lens has zero variation in magnification, and using the usual definitions, a fisheye has 100 percent distortion, orthographic or equidistant projection only providing variations in midfield. 3) Optical geometry allows for nothing else. * Henning J. Wulff /|\ Wulff Photography & Design /###\ mailto:henningw@archiphoto.com |[ ]| http://www.archiphoto.com original message: >As you know, the principal difference between a retrofocus and a symmet, >is that the >symmet images at (or close to) its focal length and the retrofocus >provides some room >at the rear by placing a divergent group in front of a convergent one, >effectively >shifting nodal planes back, behind the lens. > >Considering that the angle of oblique ...etc <snip>