Originally Posted by
Dan Fromm
Ron, BIV3 decodes as special mount B ("objective mount fitted with iris diaphragm and fixed flange", without focusing helical), size IV subsize 3. All this except subsize 3 is in the 1901 Zeiss catalog I pointed you towards and the 1910 Zeiss catalog in the list. Subsize 3 is the mystery, everything else is clear.
The catalogs give the very strong impression that subsize indicates barrel length.
Sorry, you can't post to my list and anyway it has no forum attached. This is the place to ask, I'm glad you asked here.
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