At 12:34 AM +0100 12/12/07, Willem-Jan Markerink wrote:
Puzzling details:
The angle of view of the 10mm varies with the mount/camera/chip-size....
154 degrees (180 for Nikon, 167 for Canon)
http://www.sigmaphoto.com/lenses/lenses_all_details.asp?id=3336&navigator=6
....while the 4.5mm has a single/fixed angle of 180 degrees....
http://www.sigmaphoto.com/lenses/lenses_all_details.asp?id=3336&navigator=6
Well, the Nikon chip is slightly larger, so it gets the full 180
degree diagonal while the image is slightly 'cropped' on the Canon
chip, whereas for the 4.5mm lens the image circle is probably just
smaller than the Canon short dimension, so the full image of 180
degrees can be produced on both chips.
--
* Henning J. Wulff
/|\ Wulff Photography & Design
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