Are we talking in general, or in the class of lenses mentioned in the post I was commenting on? Lens with ground aspherical elements usually could not even be made without them, but they are insanely expensive. In fact some of those with molded plastic aspherical elements would not be economical with out them. Context is often very important in these discussions, ignoring it makes it a different discussion altogether.
Ciao, Graywolf http://pages.prodigy.net/graywolfphoto ---------------------------------------------------------------- ----- Original Message ----- From: Aaron Reynolds <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Thursday, March 14, 2002 12:59 PM Subject: Re: 28-70 vs 24-90 vs 28-105 > On Thursday, March 14, 2002, at 11:34 AM, T Rittenhouse wrote: > > > AL, a molded plastic non-spherical element, instead of several glass > > elements. A cheaper way to build a lens. > > Not entirely -- > > 1) the element does not have to be plastic (though often it is) > 2) AL elements can be used to minimize distortion far more efficiently > than a series of traditional elements, resulting in a sharper, brighter > lens with less distortion > 3) I don't know that AL elements are any cheaper -- if they were, > wouldn't Vivitar's cheapass 28mm prime be an AL lens? > > -Aaron > - > This message is from the Pentax-Discuss Mail List. To unsubscribe, > go to http://www.pdml.net and follow the directions. Don't forget to > visit the Pentax Users' Gallery at http://pug.komkon.org . - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
