Re: Beginner's question answered

[P3D Brian Reynolds <reynolds@xxxxxxxxx>]

John R wrote:
> 
> >Date: Mon, 9 Jun 1997 18:06:26 -0500
> >From: P3D Brian Reynolds  <reynolds@xxxxxxxxx>
> 
> >The twin bar and the slide bar make it surprisingly easy (at least to
> >me) achive results.  Not necessarily good results, :) but I can see a
> >stereo effect.
> 
> A slight caution which doesn't necessarily apply to you: sometimes
> when a person getting into 3D views a reversed (pseudoscopic) stereo
> image, they make that exact same comment. At one point when I was a
> teenager and had no exposure to 3D other than Viewmasters, I would
> take a stereo pair of prints, dutifully place the left view on the
> left and the right view on the right, then *cross view* it. :-) A
> way to check for this is to see whether it looks better when you
> swap the two views. The next typical pitfall of the beginner is
> toeing in the camera(s) to get converging views.  As I mentioned, I
> have no reason to believe that this caution applies to you, but it
> may be useful for some people starting in 3D.
> 

Actually I did reverse my first stereoscopic pictures.  I took them
with the pinhole camera and a slide bar and dutifully marked them as
to which was taken in the left position and which in the right.  It
wasn't until after I didn't see much effect (which I attributed to the
pinhole not being razor sharp) and thought about the camera's point of
view vs. my point of view while viewing that I swapped the polaroids
and got a much better view.  I then rushed off to my web page and
corrected the images there. :) Now I look for which image has more
information on the left edge and use that as the right half of the
pair.

A comment by someone on the photo-3d list (or the FAQ) warned me about
toe-in.  Having only read the historical books reprinted by Reel-3D I
might have gone that route if not for this list.  I guess I'll have to
pick up a modern book.  The book by Ferwerda has been on my shopping
list.

> >What I would like information on is:
> 
> >6. Antique stereo cameras
> 
> >I'm specifically interested in turn of the century (give or take a
> >couple of decades) large format stereo cameras (e.g., like the one
> >depicted in "Across the Sea of Time").
> 
[my questions and design speculation trimmed]
> 
> The width of the ones I've seen is typically around 3", and the
> height may be 3.5" or a little higher. For modern Holmes cards,
> regular glossy 3.5"x5" prints trimmed to 3" wide (made from 35mm
> negatives taken through a 50mm lens) work very well. The trimming is
> done in the proper relative positions to set the "stereo window".
> 

Sounds like using two sheets of 4x5 film is the way to go.  I guess
I'll use the 135mm lens.  "Normal" is about 150mm, but buying a pair
of lenses (instead of using one lens I already have) would get pretty
expensive for a one off camera.

> Somewhere (Ferwerda's book???) I got the impression that the stereo
> cards of the 1800s were usually *contact prints*, made from a
> negative of the same size.
> 

I expect to contact print the images for my stereo cards.  Not needing
an enlarger is a plus for large format.  :) Trying to get reasonably
priced 4x4 enlargements from the 120 film is another reaseon to go
large format.  Besides contact prints can be done with some of the
alternative processes (e.g., platinum/palladium, cyanotype, etc.) for
additional unusual effects.

-- 
Brian Reynolds                  | "Humans explore the Universe with five
reynolds@xxxxxxxxx              |   senses and call the adventure science."
http://www.panix.com/~reynolds/ | - Edwin P. Hubble


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