On 10 Mar 2005 at 9:42, Rob Studdert wrote: > At wide apertures the image forming rays pass through the lens over the entire > aperture opening and all focus at the film/sensor plane so the image forming > rays are coming from a wide range of angles so any object suspended above > obscures only a relatively small area of the image forming rays.. > > At narrow apertures the image forming rays pass though a narrow opening hence > that are conformed to pass though the dusty filter above the sensor surface at > limited angles hence anything in their path will be rendered as a more obvious > shadow on the image forming plane.
My apologies to anyone with English as a first language :-( Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://members.ozemail.com.au/~distudio/publications/ Pentax user since 1986, PDMLer since 1998
