Re: [photo-3d] Loupe question, magnifiers, confusion

[Paul Talbot <ptww@xxxxxxxxx>]

Abram Klooswyk wrote:

> "Magnification" of lenses is well defined in optics, and its
> calculation is not very complicated.

> But for the magnification of handheld magnifiers a different
> definition has been adopted, 

What is your distinction between "lenses" and "magnifiers?"
You seem to place loupes in the magnifier category.  Are
camera lenses in the "lens" category?  And in what category
are lenses used in stereo viewers?

If viewer lenses are in the "lens" category, how is their
magnification calculated?  In several years of reading a few
different 3D lists, the only magnification formulae I've seen
are the 250/fl you mention, and 250/fl + 1.  What is the
reasoning for the +1?

Paul Talbot