On Fri, 1 Dec 2006 15:36:46 -0800, Henning Wulff <[EMAIL PROTECTED]>
wrote/replied to:

>>You'll never convince me though that if the optical circle doesn't 
>>need to be so
>>big, that the glass lenses used can't all be a bit smaller. Why do you think
>>medium format lenses are all so fat?
>
>Because for the most part they're made with different criteria in 
>mind. Manufacturers know that people buy (bought) MF equipment for 
>high quality, so everything about the systems was optimized in that 
>direction. Weight and size were not the main concerns. Durability, 
>high sync shutter-in-lens are things of importance.

Yes, and the Sigma made for smaller sensors is made with different criteria in
mind, that's my point. It's made for someone who wants a thinner, lighter lens.
That is the design objective they start off with and I guess they manage to trim
it down considerably. Otherwise nobody would buy it.

We haven't touched the optical laws of physics here though, about making a
bigger image circle. I guarantee you it requires bigger glass not smaller and
vice versa.

-- 
Jim Davis, Owner, Eastern Beaver Company:
http://easternbeaver.com/ Motorcycle Relay Kits,
Modulator Kits, Powerlet, Centech, Posi-Lock, Parts.
1988 K100RS SE ABS in Japan. 1991 ST1100 in America.
STOC#6327, IBMWR, KBMW
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