[MF3D.FORUM:1376] Re: Larger aperture size for twin rig shots?

["Don Lopp" <dlopp@xxxxxxxxxxxxxxx>]

I believe that Greg has it totally right. The 55mm film gates allow 5mm to
play with  even allowing 2.5mm for deviation leaves 2.5 mm extra( not much
though ).I believe that the biggest problem is aiming the cameras which can
be assisted with the use of a precision shift bar or by having critically
accurate view finders carefully used so that one does not squander the 2 mm
available.The panoramic mounts were designed too narrow ( 51.5mm ) which
leaves only 3.5 mm for deviation , at most. Wider film gates are therefore
required if one wants to use the panoramic slide mounts for hyper stereos
using separate cameras or possibly narrower panoramic mounts in the future ?
I assumed that the panoramic mounts were originally designed for use with
films taken with panoramic cameras which have 58mm wide film gatesp- just a
guess? 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
>
>