Re: RBT mounts... - alignment

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

>The question is not if errors are acceptable, but if you can see them or
>not.  I can detect aligment errors in the viewer.  

Let me add here that in my red button viewer the image is 3 times larger
than the projected image from my projectionist seat using 5" lenses (this
is true for any size screen or projected image).

The advantage of projection is that the two images overlap so you can check
alignment everywhere in the slide, not just top and bottom as in the
viewer.  The trick with sliding an aluminum mount (or any other sharp edge)
will let you scan-check alignment one line at a time.  Sometimes, I move my
eyes away from the eyepieces and play with the interocular.  This way I can
check for alignment around the center.  This check will also test alignment
of the viewer lenses (not many people worry about this) and it similar to
techniques used to check alignment in binoculars.

-- George Themelis


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