P3D One Sided anti-newton Glass & RBT mounts: Purpose

[Jon Golden <3dman@xxxxxxxxxxx>]

Mark Hatfield <HatfieldMk@xxxxxxx> asked about anti-newton glass in RBT
mounts...and its purpose.  Here is a some collective information, in
response to some FAQ's of info that I use to answer questions.

RBT glass slides are meant, first and foremost, to provide the extremely
accurate flat image plane that is required to obtain sharp focus across
both slide apertures, to the corners, when projecting.  The strength
rigidity, and calibration of the plastic RBT mount facilitates (along
with proper mounting) accurate an consitent image positioning.

Q: Is the anti-newton glass is a form of protection as well?

Of course it is, from fingerprints.  However, I would not say that is
guaruntees much protection from extreme bulb heat in your projector. 
Mainly found with the older projectors, if your images are getting
damaged from bulb heat, then the projector has a probelm.  I suggest
contacting Dr T. who seems to know a lot about proper ventilation for
the TDC's, Compcos...etc.

Newer projectors like the RBT 101, Brackett Dissolver, or the newest
Fader system....run so cool that heat is a non issue.

The RBT white halve was designed to reflect heat from bulbs, if in fact
heat is an issue.  Using the black side of the RBT mount in an RBT 101
or a Brackett projector is no problem though.

The black/white setup of an RBT mount also helps to orient the slides
for projection, hand presentation or organization for storage

For hand or exhibit viewing, using the white or black side facing the
lenes is a matter of subective choice.  Some people use all black RBT
mountsk, thay can be ordered that way at no extra charge.

Q: Is it just glass on one side?

Yes....the anti-newton surface backs up on to the base side of the film
chip.  Analogy: Think of yourself as a film chip, your back is the
base...you stomach is the fragile emulsion side...and an RBT mount as a
kind of system that holds you flat against the wall....wont let you bend
over forward...which is eqaul to a film chip popping from projector
heat.

Q: I'm a little surprised that the price is so close to the non-glass.

Well, unlike the older systems, RBT's dont use an entire piece of glass
across the whole surface of the slide.  So there is less glass to make
and less glass to ship (ever bought a pack of glass...very heavy!)
RBT glass mounts use an anti-newton glass insert for the L and R
apertures, each insert being just a bit larger that a full frame
opening, and nesting flush in to a special white 23 x 33mm format halve
of the RBT mount....which has a nesting shelf to accept the glass
insert.  This white halve is a universal piece for ALL RBT anti-newton
glass mounts only, you would not use it with non-glass mounts.  Then, to
get the image masked down to the format you want to use, the black halve
handles that chore, with apertures of:
23 x 33 RBT Full
23 x 31.5 (RBT wide
23 x 28 RBT Euro
23 x 21 RBT Realist
21 x 16 RBT Nismlo/Half Frame/Beam Splitter,deWIjs MACRO


Q:Are the mounts the same except for the glass?  Are
they the same thickness 

No difference in thickness for glass on non-glass RBT mounts, differenc
in thickness pertains to the EMDE or Albion or eauivalent systems, where
the glass is sandwiched on the outside of the mount mask, and further
thickness is introduced if the outer aluminum binder is used.

As for RBT glass vs. non-glass.  I suggest for most people...to use
lower cost, easy to use RBT non glass mounts....and save the anti-newton
glass RBTs for their projected or protected images.  Any further
questions feel free to contact me.

Regar-D-D-D-s Jon G


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