On 25 Jul 2005 at 12:18, Bertil Holmberg wrote: > Paying dearly for a [used] Pentax lens and then only using part of it > for the rare shot that needs these extreme angles seems a bit silly > to me. So I'm considering the Zenitar instead that can be had brand > new for $105 + S&H from Russia.
Hi Bertil, When a 15 or 16mm lens is used in conjunction with any current Pentax DSLR quite a bit of the wide angle effect is lost due to the sensor crop factor. For those of us who actually used to put ultra-wide lens into use regularly in the days of film these lenses are not really wide at all on DSLRs. > Thanks for the field-of-view calculator link! This does not explain > the 180 degrees claimed for some fish-eyes though. Are these a > special case? The Pentax fish-eye lenses are what is generally referred to as full-frame fisheyes in that their image circle doesn't fit within the frame but is designed to provide 180 degrees across the diagonal of the frame. A full-frame fisheye lens designed for 35mm film use will provide a diagonal angle of view of approximately 118 degrees across the DSLR frame. Due to the spherical projection type the more visible distortion visible in a full 35mm frame will be cropped so it will render more like a rectilinear lens with severe barrel distortion. Cheers, 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
