> Date: Wed, 07 Mar 2001 14:05:11 -0500 > From: "F. Craig Callahan" <[EMAIL PROTECTED]> > Subject: Re: FD vs EOS > > I won't say anything about the optical quality of EF vs. FD lenses because this > discussion contains more heat than content, other than to suggest that to assume > that the newer lenses are optically inferior just because one doesn't happen to > care for the construction of those lenses is, um, ill-considered. They do care for the construction very much, but in an array of goals with optical and mechanical precision versus compactness, weight and projected strret price, the emphasis all too often is not laid on max optical performance. Else there would be nothing but "L" lenses.... Just take a look at the amazing sales numbers of soup zooms like the Tamron or Sigma 28-300 mm, and you know that people don't shop for quality very often. > "1935: > Professor Alexander Smakula developed anti-reflex > layers for glass surfaces (Carl Zeiss T-coating) in the > Zeiss works. I knew it was Zeiss, but I am stunned to see it was *that* early in lens making. > That said, it is interesting to note that Nikon has just announced a new 45/2.8 > Ai-P lens that uses the classic Tessar design--four elements in three > groups--developed by the Zeiss company in . . . 1902. Loads of lenses are basically abstracted from Gauss types, Tessar and Sonnar designs, original Zeiss inventions. Good ones as well as cheap bottle bottoms. Yes, quality of the implementation is crucial. > it seems to me that it's entirely possible that non-metallic > composite materials could have distinct advantages over various > metals for lens construction, in terms of things like > expansion/contraction due to temperature or resistance to > deformation. Yes, perfectly correct. "Metal" does not equate to "better than plastic". > Perhaps it's irrelevant, but I notice that many EF lenses have a > built-in compensation for focus shifts due to temperature-induced > expansion and contraction; this seems like an advance to me, not > compensation for some design flaw. Also correct. And this is indeed possible due to higher computing power. The lens designer can indeed calculate the control curve for the compenastion mechanism in acceptable time. The point is that one can use this to make a lens better ... or smaller and more lightweight. I do not mind to carry the EF 1.2/85 mm L or the EF 2.8/20-35 mm L for that reason. I did frown at the price tags though..... -- Michael Quack <[EMAIL PROTECTED]> http://www.photoquack.de * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
