[MF3D.FORUM:333] Re: BASE = 1 in (FL of Lens) "rule"

["Stuart Johnson" <gcsphoto@xxxxxxxxxxxxx>]

Hello Bill and the rest of MF... This is in response to Bill's requests and
my reviews
of recent MF emails....  If I'm "way off" with my opinions, please let me
know....

I started to write to you with my opinion and after I read Tom's and others
"formula's" I realized that in my opinion.... That these formula's may not
be right!   The MAIN thing is to capture an image that looks NORMAL.  Our
eyes do NOT shift left/right in directions -only the eyeballs have an
ability to turn "in".  They do this all the time.  When you place the lenses
FURTHER apart, you get EXAGGERATED stereo to some degree (from minimal to
extreme).  I can't agree with this formula that some seem to be fixed upon
at 1 in 30 or 1 in (FL of Lens). Why?  Because my experience has shown that
I can have a perfectly NORMAL 3D photo where my foreground is only 3 feet
away!  Also, that I can compensate for the Stereo Window placement by how I
trim and mount my Prints. Finally, if Tom's formula is correct ( Base = 1 in
FL of Lens ) then if I have a 100mm Base with my Hassy's and use 80mm
lenses, then the CLOSEST I can have my foreground is...  26 feet.  This
can't be right....  If it is, how would I ever be able to take a portrait in
stereo?

For example:  You can set up two 35mm cameras with 50mm lenses at 70mm base
and have foreground as close as 4 feet and take a beautiful stereograph.
According to some, this is not supposed to work! You can also tilt the
lenses IN a little (5 degrees) and limit the background (no infinity) and do
the same thing. This too is not supposed to work according to some.

Now, when you exaggerate the BASE then the images tend to look...
exaggerated.  Mainly the objects get smaller, and tend to 'lift off' the
picture...

You may want to check out the tables in WAACK's book (from Reel 3D) or
Ferwerda's book (Expensive if you can find it).   What are our eyes focal
length? It must be quite small....

Finally,  I shoot in Prints and it appears that the viewing of prints is
different then viewing the Medium Format SLIDES.  Perhaps someone with
experience with bot formats can better answer your question...

Good Luck!    -I've got a lot more reading to do!

 -Stuart