[MF3D.FORUM:596] Re: lens question

[Paul Talbot <ptww@xxxxxxxxx>]

Bill Glickman wrote:
> 
> An 80 mm lens is used because its "normal" in MF, and because it also
> matches our viewers lenses.  When I tried a 43mm lens, the scene did not
> look natural, it simply looked too wide... as if my brain knew my eyes can
> not see like this in the real world.

That could be part of it.  Another problem is that when the
viewing FL exceeds the FL of the shooting lens, the z-axis
is streteched in the reconstucted view.  A person pointing
his arm at the camera would appear to have a 4 foot long arm.
That kind of thing.  Potentially useful and entertaining in
the right situation, but not "normal."

>       My question is, if you use a 150mm lens and use John B's fourmula for
> the taking base.... how does this look in the viewer?  Unnatural?

When the shooting FL exceeds the viewing FL you have the opposite
effect--squash.  The person's 2 ft arm would appear to be only
1 foot long.

> I would
> think it would look identical to the 80mm since it would produce the same
> chrome if one stood twice as far away from the subject?

Careful there, or John B just might have to slap your wrist!  You
never have the same chrome if you change perspective.

Paul Talbot