Re: [photo-3d] LEEP camera / architectural 3d

[Brian Reynolds <reynolds@xxxxxxxxx>]

Boris wrote:
> Otherwise I am thinking of just plain old medium format
> transparencies for this project - shift/tilt capability would be
> useful, I think.  Has anyone shot with shift/tilt in stereo and what
> pitfalls await me there?  Does 3d viewing make shift/tilted images
> look even more strange than they already do flat?
> 

>From the sounds of other's descriptions of the LEEP system this is
probably the better plan.

I haven't shot many Large Format pairs (and light leaks ruined the
ones I did), but I plan on doing more on my next long trip.

I would recommend that you rent a 4x5 (inches) monorail camera, a lens
of the appropriate focal length and a 6x6 rollfilm back.  You can find
6x9 (centimeters) monoroail cameras (e.g., the Acra Swiss F-Line) and
rollfilm backs, but they are not as common as 4x5 cameras.  If you do
rent a 6x9 monorail you might still want to use 4x5 lenses because
they will give you the ability to use more movements.  If necessary,
you can rent via mail order.  I'd also recommend Norman McGrath's
"Photographing Buildings Inside and Out" and Steve Simmons' "Using the
View Camera".

The various Medium Format cameras with built-in shift and tilt (e.g.,
the Hasselblad Flexbody, Fuji 680) all have very limited movements,
are heavy (compared to a proper view camera) and have a limited
selection of lenses that work with movements.

Camera movements should not make the subject look strange, unless of
course the photographer chose to do so.  There is no reason for camera
movements to look strange in stereo, unless the photographer chose to
do so.

There are two types of movements (rise/shift, swing/tilt) and two
places (front and back) where movements can be applied.

Movements at the back of the camera can not effect the perspective.
Perspective can only be controlled by changing the lens to subject
orientation.  If you imagine an infinite plane at the focal plane, the
rise or fall or left or right shift of the camera back simply selects
(within the limits of the lens' image circle) what part of that plane
you are getting your image from.  Tilt and swing of the camera back
effect the shape of the image (by changing the lens to film projection
distance (i.e., magnification) of different parts of the film).  This
is how view cameras can take square pictures of buildings.  By keeping
the back of the camera parallel to the building face (mostly through
tilting the back to keep it vertical) the building looks square.

Movements at the front of the camera effect perspective (rise/shift)
and focus/DOF (tilt/swing).  Perspective control is useful when you
can't put the camera where you would like.  For example, if there is a
mirror in the scene, and you don't want the camera to show, you place
the camera to the left of the scene and shift the lens to the right.
For interiors you probably will stop down the lens rather than use
tilt or siwng.

When shooting interiors there are two things to keep in mind.  First,
it is very important to keep the camera level (both left/right and
fore/aft), especially when using very short focal length lenses.
Second, you have to be careful about your lighting and film type.
Interiors will very often wind up involving mixed lighting (natural,
tungsten and flash).

The easiest way to do stereo with a large format camera is to put the
camera on a slide bar or macro focusing rail.  Set up the camera for
the scene with whatever movements are needed.  Take the first
exposure, slide the camera and then take the second exposure.  You
could use the camera shift to do the slide, but if you've used swing
or tilt at either the front or back things become much more
complicated.

The books I mentioned above go over all of this (with diagrams and
examples) much more clearly that I can here.  Feel free to ask any
questions.

-- 
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"