P3D Re: Mounting Gauges

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

Andrea writes:
 
>I wouldn't say I would be *totally* lost without the gauges, but I will 
>say they have definitely helped in improving my slide mounting and to 
>speed it up! 

Speed it up?  I am very surprised to hear that because using a mounting
gauge will slow my mounting to 10x (I am just guessing...)

>The horizontal lines are invaluable for making sure the 
>chips are in line with each other. It is so easy to be a mm off or for 
>one chip to be slightly rotated. ... Our club highly recommends 
>the gauges, especially for beginners.

May I present a different point of view here? :-)  I do not recommend
a mounting gauge to a beginner using a standard stereo camera because
it can easily get them confused or give them the wrong impression that
accurate mounting is difficult, time-consuming, etc. 

A beginner can mount fast and accurately with a little practice.  When
using a standard stereo camera, the chips are aligned already. Most
mounts provide a rigid edge ("Spicer" is an exception but there is a
mounting jig that takes care of that)  If you just push your chips
down against this rigid edge and center them to their mount openings 
then you have good to perfect alignment with only a small shift needed 
to reposition the stereo window.  If a beginner cannot mount slides well 
without a gauge, then it is very likely that he/she cannot mount them 
with the gauge.

The above comments apply when using standard stereo cameras.  In the
case of excessive parallax or use of single cameras handheld, etc.,
or if mounting to constant infinity separation then the gauge does
help.  But even when I use hand held SLRs I still don't use the 
alignment gauge.  I just need to make sure that the bottoms (or 
tops) of the chips are being cut at the same location by the edge 
of the mount.  Of course, then can be errors built into the pair, 
like keystoning, rotation, or dissimilar size (when using two cameras)
but the gauge cannot help you in these situtations.

On the same subject, Tony writes:

>However, the horizontal lines can be useful in checking
>for vertical and rotation errors--even if your camera is accurately
>aligned, there is some slop in the masks. 

You are opening a can of worms here... :-)

The bottom line is that I have been mounting for years, a variety of
stereo slides in a variety of mounts, without much problem.  I tried
to use mounting gauges with the Spicer mounts and that did not work
to my satisfaction because I could not see the lines very well (you
need high magnification to see the details and I was using just 
"reading glasses" or a 150 mm FL viewer) and I found the lines to be
too thick for accurate mounting.  I ended up buying the Spicer jig
and don't need the gauge there either.

Just my humble opinion :-) -- George Themelis


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