As an (important?) aside, I recently bought the Sigma 10-20mm f4-5.6 (used) and read that it WILL cover a full 35mm frame down to 13mm. I plan on trying this myself with my Z-1p. I'm sure the corners will suffer, but WOW... a 13mm rectilinear focal length with no field-of-view crop? If true, it is amazing that they don't promote this. Lesson: Don't ASSUME your lenses designed for APS-C won't cover the full 35mm. They just may not do it over the whole zoom range.
> The equivalence is more of a shorthand for photographers who were > accustomed to how 35mm focal lengths worked, and it has really > outlived it's utility. Well a focal length is a focal length is a focal length but if you are an old school 35mm film shooter then a particular lens focal length translates in your mind to a particular field-of-view. When you crop that you haven't changed the effect of the focal length (think: squashed depth with a particular telephoto focal length, for example) but you HAVE changed the field-of-view. For a radical example illustrating this principle, put a F 17-28mm fisheye zoom on a Pentax DSLR. You've still got the fisheye distortion you associate with ultrawide, but you are cropping the center out of the field-of-view (an effective 25-42mm with fisheye curves... which can be very interesting!) Bottom line, if you think in terms of field of view, AND you used to shoot film (or you STILL also shoot film), the equivalence continues to have more than a little utility. It is similar to an older American who will always need to convert metric units to imperial units in order to grasp what is being talked about. A younger generation that simply learned the metric system without having the base knowledge of imperial units would certainly not need that utility. Darren Addy Kearney, NE -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
