> At 10:16 AM 2/1/01 -0800, BW wrote:
>
> There may not be an exact definition of a Tessar
> lens. One optics text
> does call many of these "Tessar form" lenses, but
> the classic Tessar lens
> is a 4-element lens, with a max aperture of f/2.8
> or f/3.5. An example
> of a lens that is not a classic Tessar type is the
> Pentax 40mm f/2.8
> lens. The Pentax lens is a 5-element, 4-group
> design while the Nikkor
> and Zeiss Tessar (Contax mount) 45mm f/2.8 lenses
> are 4-element, 3-group
> designs. Once you get beyond f/2.8 or wider than
> 40mm (for 35mm
> cameras), lens designs tend to be very different
> from classic Tessar
> lenses.
>
I ~think~ the M-50mm/4 Macro is such a classic Tessar
lens.
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