Re: 3D Carousel Projector

[xid@xxxxxxx (David C. Glick)]

PHOTO3DGUY@xxxxxxx says:
>I've been trying to find out if anybody thinks a 3D carousel projector is a
>good idea, but no input on 1st 'go around'. 

Well, I think it's so good that you've prompted me to make my first post to
Photo-3D.  It's good because these are reliable modern projectors which
cover 8-perf with options available for various lenses, remote control,
automation, etc.  

It's often mentioned that Kodak Ektagraphic carousel-style projectors have
"positive gate registration" but consumer-oriented Carousel projectors do
not, so only the former should be used for stereo projection.  Could someone
say exactly what "positive gate registration" is?  Is it just a
spring-loaded arm pushing the slide against a fixed stop?  Could it be
retrofitted to a Carousel if one were in there modifying it anyway?

>The concept was to make the carousel trays accommodate a 4" 3D slide and
>widen the carousel projector to accommodate the larger tray and one
>additional lens to the right of the existing lens.  Add a second bulb, second 
>fan

Widening the projector with an additional lamp, fan and lens is great as
long as the two optical paths can be placed close enough together.  I just
measured the diameter of a recent 100-150 mm f/3.5 Ektagrahic lens barrel
and it's about 66 mm (not good!) at its widest; the part that's inserted
into the projector is less.  If the parts/modules that need to exist in
duplicate in the projector are more than 60 mm or so wide, they would have
to be modified, making the job much harder.  Has anyone measured any of the
pertinent parts?  I've been playing around inside a Bell & Howell and a
Reflecta recently, but not an Ektagraphic.  

Making carousel trays for 4" wide slides sounds like a lot of work -- the
outer sections would have to be made from scratch.  (Unless the added
optical path could be inside the normal circle rather than outside, but I
don't think there's room for that.)  If they were European- style straight
trays there would be some hope of splicing two together.  

Instead of trays, how about modifying a stack loader to 4" width.  Then no
trays are needed  -- a big advantage.   Just grab a stack of slides out of a
box, plop them in and start projecting.  Stack loaders can be more finicky
to use than trays, but maybe that can be overcome.  A modified stack loader
would probably have to be made for a specific thickness of slide mount, or
have an adjustment for mount thickness.  

>The other concept was to design the carousel so that it could accommodate
>either a regular 2D tray, or a larger 3D tray with 'gear shift' lever. 

The cogs on the bottom of the normal tray are adjacent to the slots, not the
dividers, so they could not remain at their normal position in a wider tray,
nor could the mechanism  that drives them.  In the modified projector the
mechanism would be 2" farther out and would not mesh with a normal tray.  I
don't think a lot of extra work to retain compatibility with 10" diameter
trays would be justified.

Let's have some more thoughts!

David Glick          Penn State            xid@xxxxxxx


------------------------------

End of PHOTO-3D Digest 1182
***************************