Re: RBT/Spicer mounting issues

[P3D Dr. George A. Themelis <DrT-3d@xxxxxxxxxxxxxxxxxxxxxxxxxxx>]

> First, DrT mentioned that the apertures of the 5P Spicers seem to have
> some rotation error.  What I have observed is that the perimeters of
> a 5P Spicer do not "square up" precisely with an RBT.  

That's what I have observed too.  I mentioned that I "correct" this by
rotation because what was the most convenient way to line up the
apertures.

> Although I have not tried to correct for this
> difference, in viewing my slides I have not had any discomfort
> related to the edge alignment problem.

The difference is small.  But it is observable and you don't need to
be a rocket scientist to see it.  I am glad to hear that Paul can
see it too.  I am in good company!

>Second, the aperture of the 5P Spicers is taller than the aperture
>of the RBTs.  

That's interesting.  I was suspecting that the RBTs have smaller 
apertures and I see some advantages to that (more room to manipulate 
the images).  But the Spicer aperatures are smaller than the Albions 
that I use for my transfer, which is convenient.

> Third, and most significantly, the windows of the RBT and Spicer
> are not the same.  

I have noticed that too.

>This has caused numerous problems in my attempts
>to use the RBT as a jig for the Spicers.  When cropping close to
>an edge of an image, one chip sometimes ends up with light leaking
>past the edge after the transfer to the Spicer.  

That's annoying, isn't it?  I don't have this problem since the 
Albion mounts have wider windows so I see the image framed by
the Spicer mounts during the transfer.

>When cropping out
>something close to the camera at the edge of a scene in the RBT, the
>object may reappear and cause a window violation after transfer to
>the Spicer.  When mounting very precisely to the window based on
>the results as previewed in the RBT, objects will inappropriately
>stick through the window

The opposite is true for the Albion mounts.  When transferred to
Spicers the objects are pushed a bit back.  I compensate for that
by mounting them tigher in the Albion frame in the first place.

>I suppose you could call it "really pushing the limit" but I have
>found that when mounting to the window for slides that will be
>projected, it is critical to place the nearest object as close
>to the window as is humanly possible.  If the nearest object is
>the slightest bit behind the window, the stretch of projection
>makes it look a looooonnnnnnggggg way behind the window.  

It is a propotional effect.  Between touching and beeing too
loooooonnnnnngggg there is a "just right" for most images.

>I still think the RBT jig/Spicer procedure is a great way to save
>on out-of-pocket costs for mounting.  But there are some inherent
>obstacles to precision mounting that must also be considered.

Nice summary. I know what your problem is Paul!  You are very 
demanding. :-) I am glad that you pointing these inconsistenscies
out and I am surprised that others don't see them.  For me, the
Spicer mounts are not for precision mounting and are not for
projection.  They are for handviewing only.  For projection use
RBTs.  But how many of your slides are projected?  Less than 5%
of mine.  I just remounted all my "scientific" slides (originally
mounted in Spicer mounts) to RBT mounts.  More about that in the
next posting.

George Themelis, 
Back from Chicago and still looking for the perfect mount...


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