ATM 2" Filter Thread Dimensions

["Sidor . Kurt" <KSidor@drc.com>]

>From the "ATM Page" I got the dimensions for 2" filter threads.  All it said
was 48 mm pitch diameter and 0.75 mm pitch.  Does anybody know the major and
minor diameters?  I am also aware that there doesn't appear to be a true
standard for these threads, I have an Orion 2" prime-focus adapter with what
appears to be a thread pitch of about 0.5 mm rather than the 0.75mm.  I do
not currently own any 2" filters.

Thanks!

Kurt Sidor
Mechanical Engineer
Dynamics Research Corp.
Encoder Division