At 4:42 PM +0900 12/1/06, James B.Davis wrote:
On Thu, 30 Nov 2006 22:22:29 -0800, Henning Wulff <[EMAIL PROTECTED]>
wrote/replied to:
Making it for the smaller sensor doesn't really allow making it
smaller. That's the whole point.
Maybe not, but when the goal is to have something smaller and
lighter, there are
ways of doing it. Like more plastic, thinner walled tubes, etc.
...which has nothing to do with the format. Canon has done a great
job of reducing the size and weight of their 300/2.8IS over the years
while not even resorting to plastics or, as far as I know, reducing
the structural rigidity of the lens.
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.
As I posted earlier, minimum glass sizes for the front of telephoto
lenses are dictated by the laws of optics and have nothing to do with
format. To some extent the rear elements of lenses can be made
smaller for smaller formats, but they tend to be fairly small and
light anyway, and are not major factors. For telephoto lenses the
front elements are the big, heavy and generally the most expensive
items and they are determined purely by focal length and aperture.
When you get to longer lenses, which is what this thread was about
originally, and there are no between lens shutters to muddy the
waters, you find that the lenses aren't a whole lot different in size
and weight for MF than for 35mm. See the 300/5.6 for the Mamiya 645
or the 300/2.8. There is some additional material and weight required
due to the larger mount, but otherwise they aren't particularly
larger than lenses for smaller formats.
--
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
--
* Henning J. Wulff
/|\ Wulff Photography & Design
/###\ mailto:[EMAIL PROTECTED]
|[ ]| http://www.archiphoto.com
...my ride: http://www.archiphoto.com/Various/GT3/index.htm
*
****
*******
***********************************************************
* For list instructions, including unsubscribe, see:
* http://www.a1.nl/phomepag/markerink/eos_list.htm
***********************************************************
