On 24 Jul 2002 at 19:00, [EMAIL PROTECTED] wrote: > optical vignetting? > > Hum. > > I don't know. I always believed "vignetting" was a term used mainly to > describe something else obstructing the angle of view (as you say a lens > hood, filter, or even the outer part of the lens itself). > > I may be wrong but I though light fall-off was the "optical" version of > vignetting. The failure of the lens optics to adequately illuminate near the > edges of the frame. > > Maybe I'm wrong. I''ve just never heard of optical vignetting.
All lenses do optically vignette however some are more obvious than others. For example ultra-wide lenses particularly symmetrical designs where the rear element is close to the film plane (Like the CZ Hologon) exhibit very visible natural light fall off. This lens is supplied with a matched circular ND grad that can be used to correct the fall off however it also reduces the effective lens speed by two full stops. Cheers, Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://members.ozemail.com.au/~distudio/publications.html - 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 .
