In article <3F3B8626.FFB197F@austin.rr.com>, mr88cet@austin.rr.com 
says...
> > the "normal" or standard lens is usually a fixed focal lenght of 50mm.
> 
> For 35mm, yes, but what about for any arbitrary given film or CCD size?  Or
> how about 70mm movie film, or 35mm anamorphic prints of movies?
> 
> One reasonable reply directly to me suggested that its based upon the viewing
> angular distance being about the same as the human eye, and said that this
> number works out to around 48-55 degrees.  That seems plausible, but it
> doesn't say anything about width vs. height.  I'm not sure how to relate that
> rule to formats like 70mm wide-screen, or IMAX, wherein a normal lens is
> carefully designed to provide not only a normal view in the center area of the
> screen, but also a lot of peripheral-vision image content.  If you project
> IMAX onto a typical TV screen for example, it looks very wide-angle.
> 
> It seems likely then that the formulation has to include a component of how
> far away you are from the print or projection in viewing the image.
> 
> 
> 
I think you should try a different forum for this one.  A medical, math 
or science group would probably be better.  

-- 
John O.
There is no slack in light attack.