[MF3D.FORUM:1380] Re: Larger aperture size for twin rig shots?

["Don Lopp" <dlopp@xxxxxxxxxxxxxxx>]

I donot have a clue as to what OFD is but I was surprised to read of a
"built in Stereo window" found in stereo chips found in stereo cameras when
they are used while taking hyper stereo pictures-- as far as I know -each
chip is a separate picture  not containing a stereo window ? Good hyper
stereoS are usually the result of carefull technique and planning and
require carefull aiming of each camera which is not aided by most MF stereo
cameras such as Sputniks or Rolleidoscopes etc. Non SLR MF cameras or TLR
are not much better but can work if one is carefull as Mr LEE has shown us
at the convention.
II like to shoot hypers but foreground obstructions are a constant problem
especially in our built up metropolitan areas.I have shot , ground hypers
with i bases of one foot to as much as 300 feet but it was much easier 30
years ago than it is today. Airplane hypers one solution today if you canfly
in a suitable high wing , open window aircraft. Alan Griffin once sent one
hyper around of a 747  flying over Sidney ,Australia it was terriffic. DON.
----- Original Message -----
From: "Paul Talbot" <ptww@xxxxxxxxx>
To: "Medium Format 3D Photography" <MF3D.Forum@xxxxxxxxxxxxx>
Sent: Wednesday, November 29, 2000 8:25 PM
Subject: [MF3D.FORUM:1375] Re: Larger aperture size for twin rig shots?


> Still catching up on things that transpired during my
> absence...
>
> Greg Erler (sic) wrote:
>
> [re: how much room to work with twin camera shots]
> >
> >   Thus with 55mm film gates you should be able to still
> > have 55-1.35mm or so of usable area. Any non-parallel aiming
> > of the cameras could easily waste 1mm or more so that might
> > be a bigger effect.
> >
> >   Stereo base shouldn't matter if you keep the OFD under
> > control.
>
> It would take a lot more brain power than I have to think
> all the way through the implications of that observation!
>
> Here's where I see a potential problem: as the stereo base
> increases, so does the "non-overlap" image area at the edges
> of each image.  (George Themelis has posted a formula for how
> to compute the non-overlap area.)  Is it possible to have a
> large non-overlap area while not violating Greg's condition
> "if you keep the OFD under control?"  It seems to me that when
> dealing with twin camera hypers, it is the non-overlap area
> at the edges, more so than the OFD, that restricts the maximum
> size of the mount apertures.  But maybe I'm confused, as usual?
>
> Another factor that occurred to me after my post was that using
> two stereo cameras will give different answers depending on how
> the images are mixed in the final pairing, because of the built-in
> stereo window.  For example, using the left camera's left image
> with the right camera's left image will give a different result
> than using the left camera's left image and the right camera's
> right image.
>
> Paul Talbot
>
>