tombstone tops

[P3D rmt <rmt@xxxxxxxxxxxxxxx>]

Bill Walton is correct in noting that stereocard curved tops give a 
"look" that's old but not _really_ old.  But there is another reason for 
using them besides trying to emulate an historical tradition.  The 
Holmes format uses prismatic lenses which create images with slightly 
converging tops and bottoms.  That is, viewing each chip separately 
shows a taller inside edge than the outside edge.  Result:  a slight 
sense of retinal rivalry along the tops and bottoms when viewing both 
chips together.  The curved top "breaks up" these conflicting lines and 
hides the effect.  I do not know if this was the intent of the creators 
of the curved top but I believe it contributed to the popularity and 
long life of the curved top convention in the Holmes format.

As Bill states, there's no production cutter available but some 
printmakers have learned to cut them using a pattern and an exacto 
knife.  I've ruined enough chips trying unsuccessfully to do this so am 
content to use the large-diameter corner rounder as Bill suggests.
The Lassco corner-rounder takes interchangeable cutters so the same 
device can be used for rounding card-corners if desired.

Dick Twichell


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