[MF3D.FORUM:1174] Re: Camera design

[Brian Reynolds <reynolds@xxxxxxxxx>]

Greg Erker wrote:
>   Now that my SR225 (twin TLR) is 99.5% working
> my engineering mind is planning my next better
> MF stereo camera. I ran some of these ideas past
> Sam on our day trip to the mountains but maybe
> someone here would like to comment also.
> 

Someone on the Apollo project (in reference to the LM's landing radar
being developed at MIT) once said "Better is the enemy of best".

Having said that I have a few ideas on how you could make your project
more complicated, err... I mean better.

I agree with Bill that your best bet would be to start with a 4x5
camera.  You should be able to find a used 4x5 camera with a Graflok
(or International) back for not too much money.  You want a camera
with a square bellows, so that will probably mean a monorail view
camera.  Flat bed (often called field) cameras tend to have a taperd
bellows so that they can fold smaller.  You can probably use a camera
with a short rail since MF lenses are shorter focal length than LF
lenses.

Just yesterday I saw a (somewhat rough) Omega View 45E at Wall Street
Photo for $389 (before haggling), and NYC is not really the place to
find low cost used cameras.  A new Toyo 45CX is listed for $629 at
Calumet's weg page <URL:http://www.calumetphoto.com/>.  Based on a
note on the page, the price is probably lower.  (Toyo won't let them
advertise a lower price.)  Either of these cameras will give you all
the movements you could possibly want.

If you are using movements you will have the camera on a tripod, so
ground glass focusing and composition shouldn't be a problem.  Remove
the ground glass panel when you are ready to shoot and use a roll film
back to hold the film.  If you want both movements (on a tripod) and
handheld shooting you can get a press camera with a linked rangefinder
and a viewfinder (and perhaps a sports finder) like a Graflex or
Linhof.  You can also mark the focusing rail for scale focusing.

Horseman makes a 6x12 roll film back that will attach to a 4x5 Graflok
back.  Personally (given the cost) I wouldn't cut up a smaller back.

As far as lens synchronization goes I see two solutions.  First, you
could mount two lenses in separate shutters on a single lensboard and
use either a linkage between the shutter releases or a dual cable
release.  The biggest problem is that LF shutters are pretty big and
you might not get the separation that you want.  If you use two of the
Mamiya TLRs lenses this probably wouldn't be a problem.

Second you could mount the elements from two lenes on a custom board
(or use two lenses "in barrel") with a single Packard
<URL:http://www.hubphoto.com/> shutter behind the lenses.  The Packard
shutter is meant for this application (lenses in shutter, not stereo)
and is available in very wide openings (up to 8 inches).  Packard
shutters are pneumatic (operated via a squeeze bulb).  The number 6
shutter has both instantaneous (1/25 sec.)  and time (T) speeds.
Since there is an electronic version of the shutter (with not much
mention as to what exactly the electronics do) I assume something
could be rigged up to provide other speeds.  The biggest problem would
be making sure the shutter wasn't too big for the front of the camera.

I just had an idea.  You could build a camera from a 4x5 camera with a
square bellows, a pair of Mamiya TLR lenses, a Horseman 6x12 roll film
back for their SW612 camera and a custom ground glass panel (perhaps
also from the Horseman SW612).  The lenses would be mounted (with
their viewing lenses) on a single lens board at the front of the
camera.  The bellows would be interally divided into four sections.
The back of the camera would have a single panel with the roll film
back on bottom and the ground glass panel on top.  This would allow
you to compose and focus without having to fidle with the groundglass
panel in the field.

If you want to build a camera with movements I suggest looking at a
lot of 4x5 cameras because whatever you come up with is likely to be
about the same size.  Jon Grepstad <URL:http://home.online.no/~gjon/>
has a great site on building LF cameras with pointers to other sites
(including people who have built rollfilm holders).  Jon has also
written a good book (with full size drawings) on building LF 4x5
cameras.

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