Recipe For Writing Icing

Patent for Pentax 25-350/3 0.3 to 5, 6

has appeared on a website a picture of a Japanese patent for optics pentax 25-350mm F3.3-5.6ED [IF] SDM

These technical specifications:
Patent Application: 2011-8234
Release date: 01/13/2011
Filing date 05/22/2009
Focal length: 25.71-339.99mm (13:22 zoom ratio)
Aperture: 3.3-5.7
Angle of view: 4.8-60 °
Image circle: 28.48mm
Back Focus: 52.92-108.59mm
lens length: 174.86-281.04mm
Internal Focusing

The site looks like the DA * lens but it seems a mere hypothesis, since there is nothing in the text to validate. Recall that on sensor Digital APS-C focal length corresponds to a 37.5-500mm on film, comparable to the range of a "bigmir" Sigma 50-500 on full-frame. But remember even more the range of classical optics as the full-frame Canon 28-300 ... factor that would tie in perfectly with a rumor that comes to us from Turin ...




http://egami.blog.so-net.ne.jp/2011-01-14