To: "Arthur" 
From: Stan Truitt 
Cc: atm{at}shore.net
Reply-To: Stan Truitt 


Aloha Arthur,

At 5.75 inch diameter it appears that you have a relay lens that resides in
the vertical tube of a submarine periscope.  Sets of these lenses are used
to relay the image formed by the objective assembly, at the top of the
periscope, down to the eyepieces and cameras within the pressure hull.

These are normally designed to work at 1 to 1 conjugates as relay sets, and
not at infinity,  as is necessary for astronomic use.  As relays these are
superb for reimaging, but sadly, not as a normal objective.

Lookin through a Ronchi screen at at Polaris will quickly tell the tale. 
If the bands are not straight and colorless, it is probably a relay.


Regards,


Stan      20ø 51'  N,  156ø 22'  W    511 meters MSL

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