P3D On lenses

["OLE HANSEN" <olejohan@xxxxxxxxxx>]

George A. Themelis <fj834@xxxxxxxxxxxxxxxxxxxxx> wrote:
> Challenging question:  Would you say that our definitions of
normal,
> wide angle and telephoto lenses also depend on viewing conditions?
No I would not say so. The definition is based on the viewing angle
of the normal human eye, which is close to 50 degrees. A lens/film
combination with the same pictureangle is called a normal lens.
Bigger pictureangle = wideangle
Smaller pictureangle = telephoto
To see the final picture orthoscopic you should se it with the same
viewingangle as the original pictureangle. Therefore lenses are
needed
in stereoscopes, except in mirrorstereoscopes, where the images are
of such a size, that they are viewed with the normal viewingangle.

bobh@xxxxxxxxxxxxxxxxxx wrote:
> In optical theory..resolving power is a function of aperture with
the 
> fastest (lowest f/no.) having the most....
The opposite is correct - highest resolving power with highest f
number.
limited by diffraction in the aparture when it becomes very small -
f:45
and higher. Cameralenses are optimized at f:8 or f:11, and lenses
for reprophotography are optimized at f:22 or f:32.
A welldesigned Tessartype is superior to any highspeedlens when used
at f:8. The 3 lens acromats used in many stereocameras are not
superior
to anything, as the 2 element acromat was not used in stereocameras.
regards - Ole Hansen - olejohan@xxxxxxxxxx


------------------------------