[MF3D.FORUM:1178] Re: First roll run through the mysteryWhutnikstereo

["Bill Glickman" <bglick@xxxxxxxx>]

Greg

     I guess you can accomplish the same thing by shooting a grid on the
wall then projecting the chromes and measuring the difference in the worst
area then divide by the magnification factor to see how far off two lenses
are, right?

    Also, I guess you could just print trannies and overlay them... I may
have to try that....

Bill


----- Original Message -----
From: "Greg Erker" <erker@xxxxxxxxxxxxxx>
To: "Medium Format 3D Photography" <MF3D.Forum@xxxxxxxxxxxxx>
Sent: Tuesday, August 29, 2000 12:27 PM
Subject: [MF3D.FORUM:1176] Re: First roll run through the
mysteryWhutnikstereo


>
> >       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.
>