David Nelson wins pop quiz! The reason the 14mm DA lens on a istD is so damn complex is the incredible 0.307 retrofocus factor. the focal length is only about 31% of the flange distance.
The ff 20mm lens is still impressive but it only has a 0.439 retrofocus factor (f.l. = 44% of flange distance). This is a huge disadvantge for wide angle lenses in a APS camera with 35mm legacy design. The flange distance is way out of proportion for the size of the sensor for good application of wide angle lenses. JCO -----Original Message----- From: David Nelson [mailto:[EMAIL PROTECTED] Sent: Tuesday, October 26, 2004 9:08 PM To: [EMAIL PROTECTED] Subject: Re: M42 ultra-wide I think that rob's point is that while focal length is nearly the same, AOV isn't, and hence a comparison of AOV is more pertinant to the discussion of APS vs FF. Comparing the DA 14mm with the FA 20mm shows nicely how the APS lens isn't a saving in size and weight (or cost!) for an equivalent AOV. You talk about an APS camera. The *ist D is not one of these - it's a 35mm body with an APS sized sensor in it. An APS camera would have a smaller lens-film distance, a smaller mount or something like that. The *ist D is saddled with 35mm's heritage. Cheers, Procrastinating David
