TDC vs. Triad - Stereo Projectors

[P3D Dr. George A. Themelis <fj834@xxxxxxxxxxxxxxxxxxxxx>]

Sam the Hacker writes:

>The Compco Triad is an excellent Projector, and the one that has been my
>workhorse for 6 or 7 years. To me it is far superior to the TDC for two
>reasons: You have a single control that corrects horizontal and vertical
>adjustment, where the TDC has two separate controls.

Sorry, but I don't see this as an advantage... The two movements are not
related to each other. Why would you want to change them with one control? 
The vertical adjustment is via a friction pad in the Triad, which makes it a
bit "jerky" in moving around.  If you only want to change the horizontal,
you will accidentally move the vertical, which is a "no no" in projection.

>The polarisers are
>between the slide and the lens, eliminating any cross-polarization that
>might happen with the base of some slides. Some slides, especially 
>B&W ones cannot be projected successfully on a TDC because 
>of the position of the polarisers.

Mixed blessing... As we've discussed, the polarizers before the slide
absorb some of the harmful radiation that damages the image.  If the film
does not depolarize the light then the TDC arrangement is better.

>It's well built, has a steel carrier ( as opposed to some TDCs that use
>aluminum) and is very reliable.

It takes some "getting used to" to use the Triad carrier with the system of
feeding slides from both ends.  I use the aluminum TDC carrier and find it
reliable (even though I would agree that steel is a better material than
aluminum - hey, I do work for a steel company!)

>I recommend it strongly and it's worth the extra bucks.

What extra bucks?  I have always asked less for a Triad than the equivalent
TDC.  I was trying to sell a nice Triad for $235 and could not get a buyer,
no matter how hard I tried.  (Finally I sold it... and, Mike S., you got a
bargain!)

This might end up like the Realist vs. Kodak argument... There are reasons
to believe that people get used and like/prefer their first projector. 
Obviously, this was a Triad for Sam and a TDC for me.

George Themelis


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