Re: why do tele-lenses have ED glass

does anyone know why tele-lenses have ED glass, and why wide angles do not? First: As I understand it, low dispersion glass can be used to help prevent color fringing (sometimes visible as a red or purple edge on a viewed object). Since the different wavelengths (colors) of light are

Re: why do tele-lenses have ED glass

Fred wrote: [snip] Just don't ask me to explain why it is the long lenses that produce the most color fringing - g. Fred I think chromatic aberrations are harder to correct than spherical abberations. Steve Larson Redondo Beach, California - This message is from the Pentax-Discuss Mail

RE: why do tele-lenses have ED glass

the problem (faster the F-ratio). Kent Gittings Kent -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Fred Sent: Wednesday, December 19, 2001 8:39 AM To: [EMAIL PROTECTED] Subject: Re: why do tele-lenses have ED glass does anyone know why tele-lenses have ED