Archived posting to the Leica Users Group, 2010/03/31
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Henning Wulff wrote: > while lens based IS does introduce more air/glass surfaces > along with more elements, that should also be the only additional > consideration regarding decentering; ie, more elements, more chance > of decentering. The operating principle of IS or VR is intentional decentering. That's how it works. Also, the IS unit adds a LOT of air/glass surfaces. For example the EOS 100-400 L IS has 17 elements in 14 groups - that's 28 air/glass surfaces. This lens is known for sample variation and weaker image quality at the long end. Another example: the EOS 300mm f/4 IS has 15 elements in 11 groups, 22 air/glass surfaces. Known for poorer image quality than its non-IS predecessor and described to me by someone who compared it with the 280mm f/4 APO as a "cruel joke" (his words, not mine). The 280mm f/4 APO has 7 elements in 6 groups - 12 air/glass surfaces + 4 surfaces for the front protective plate and rear filter. I'd rather not muck with optics to get stability. Doug Herr Birdman of Sacramento http://www.wildlightphoto.com