Close up cameras

[P3D Bob Aldridge <bob.aldridge@xxxxxx>]

->Date:   Fri, 31 May 1996 16:33:06 -0600
->From: P3D Greg Erker <erker@xxxxxxxxxxxxxx>
->To: photo-3d@xxxxxxxxxxxxxxx
->Subject: Homemade macro camera?
->Message-ID:
-><96May31.163320-0600_cst.18276+523@xxxxxxxxxxxxxxxxxxxxxxx> 
->George wrote:
-> 
->>There are two basic stereo microscope designs:
->>
->>1. Greenough
->>2. Common main objective (CMO)
->>
->>In the Greenough system the optics consist of paired objectives and
->>eyepieces.  In the CMO system there is a single common main
->objective.

->  This makes me wonder about making a closeup camera with only
->one lens. I have an medium format camera (Ricohflex TLR) with
->an 80 mm lens. Would it be possible to put a divider from just
->behind the lens all the way to the film plane to divide the light into
->left and right halves. After developing cut up the film chips and
->mount them in Realist 5 perf or 7 perf mounts ("Oh no!" exclaims
->orthoman :)
-> 
->  The lens is f3.5 so the diameter is about 20 mm, so the center
->to center separation of the two half lenses will be about 10 mm.
->This only would work wide open since as you stop down the aperture
->gets narrower and the effective separation gets smaller.
-> 
->  But I could make a piece for the back of the lens with two
->small holes (say f/16 and 10 mm apart) then always shoot with the
->camera diaphram wide open. F/16 would allow sunny 16 outdoor shooting
->and work well with flash at short ranges.
-> 
->  With a +3 or +6 diopter lens in front, the subject distance would
->be 12" or 6" which would work well with the 10 mm "lens" spacing.
->Cropping Realist size pieces out of half a 6x6 image should allow
->for some errors in framing.
-> 
->  So is this a cheap way to get a "Macro Realist"? Or are there
->some problems due to not using two lenses (ie prism effects from
->having the image come off center thru the lens)?
-> 
->Thanks - Greg

I think what you are describing here is precisely what Pat Whitehouse,
David Burder, Derek Hawkins and a number of other close-up
stereophotographers have done. 

The principle elements of this consist of a roll film body with either a
pair of cut-down lenses in the throat of the shutter, or a single lens.
Both types use a pair of "waterhouse stops" to effectively give the
separation. 

With your 20mm throat, you could probably achieve a separation of 10 to
12mm. This would allow you to shoot at around 10 to 15 inches. Field of
view would depend on lens focal length, of course. 

You can test the theory with "Blue-Tack" to hold the lenses and stops in
place - it doesn't have to look pretty. It's the results that count!

Best of luck

Bob
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