[MF3D.FORUM:1176] Re: First roll run through the mysteryWhutnikstereo

[Greg Erker <erker@xxxxxxxxxxxxxx>]

>       I assume we are talking about mismatched pairs of taking lenses here.
>How does one determine if two lenses are mismatched by .35%.  Was this an
>optical bench test?  I assume that .35% x 80 mm is a .28mm off.  So if you
>shot a grid, would the lines on the chrome mismatch by .28mm?

  I built a jig that held the lens and
a reference grid. Then I projected the
grid on a large sheet of paper and marked
the corners (and other relevant points).
Then changed the lens and repeated.
It's all on my web page:
http://www.angelfire.com/ca/erker/twin225.html

  .28mm is what the FL's are off. If
you shot a grid that came out 50mm
on one the other one would be .28%
bigger (or smaller), so 0.14mm.

  Your eyes wouldn't notice this
but when detailed subjects are cropped
top and bottom by the mount the
two sides will be cropped slightly
differently. I could see 0.5% when
mounted but not 0.15% which is likely
below my mounting skill (getting the
bottom crops exactly aligned to
compare the top crops).

Greg E.