[ATM] Field stop locations

[John Lynch <john_lynch2007@yahoo.com>]

To the ATM Group:
   
  I'm doing an analysis of some eyepieces I'm considering for an 8" f/6 Newtonian
  telescope, and the work is getting to be rather extensive using Exel spreadsheets
  with all of my algorithms.  I'm taking into account all of the parameters, including weight distribution for a counterweight system and focuser travel.  If the eyepiece is too heavy
  or can't be focused with what I have to work with, I'm excluding it from the list.
   
  Would anyone have information about the field stop locations for the following eyepieces:
  Pentax 30mm SMC-XW 2", 30mm Rini Modified Plossl 2", and 26mm Rini Modified Plossl 2"?  I'm looking for the distance between where the telescope focal plane would have to be inside the eyepiece and the shoulder of the eyepiece where it would come to rest in the focuser.  Need this to compute how much in travel or out travel it would need.  I believe 
  Tele Vue defines this as field stop location for their eyepieces, with + being below the
  shoulder and - being above the shoulder further into the eyepiece.  Any information that 
  you could provide would be greatly appreciated.
   
  Thanks.
   
  John Lynch

       
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