T3D Re: Phanto-cam Lens system

[Brian Reynolds <reynolds@xxxxxxxxx>]

Larry Berlin wrote:
> Some of you may have read about the phanto camera on the SD-3D
> list. It requires a lens and aperture system optimized for off axis
> imagery. The intended view angle should center on 45 degrees. A
> special aperture is probably necessary that would operate off axis
> preferentially.
> 

Gee, I wish this were taking place on the tech list.

> The basic requirement of the camera is a parallel film plane and
> lens plane.  The primary interest is the view as far off axis as is
> practical to achieve by lensed optics.
> 
> The other choice is to use pinholes.
> 

Pinholes will have problems because off axis the hole is no longer
round.  This will cause significant light drop off (more than just
that due to the pinhole to film corner distance being longer than the
pinhole to film center distance).  You might want to check out the
pinhole mailing list for more information.  The archives can be found
at <URL:http://www.pinhole.com/discussion>.

> The view camera lens is better than a standard camera lens, but
> probably doesn't have as wide a view as desireable for the
> phantogram effect. Or at least restricts the range of views
> possible.
> 

Short focal length view camera lenses tend to have a large angle of
coverage.  For example, a 90mm lens for a 4x5 camera would normally
have at least a 100 degree angle of coverage (i.e., 50 degrees from
the lens axis to the edge of the image circle).  The Schneider
Super-Angulon XL series has an angle of coverage of 120 degrees.

What size film will be used?  A 35mm or 6x6 frame could be place
pretty far from the axis.  A 4x5 sheet wouldn't be able to moved that
far off axis and still have the entire sheet remain within the image
circle.

-- 
Brian Reynolds                  | "Dee Dee!  Don't touch that button!"
reynolds@xxxxxxxxx              | "Oooh!"
http://www.panix.com/~reynolds  |    -- Dexter and Dee Dee
NAR# 54438                      |       "Dexter's Laboratory"


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End of TECH-3D Digest 479
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