Nikon infinity and Metaphot circular dovetails fit AO infinity heads, accessories,
  and fit Optiphot via 49.5mm to 51mm circular dovetail adapter.
  or Optiphot 100/150 vertical illuminator

Optiphot 100/150/200 infinity scopes
  with CF Plan infinity objectives

• This Eclipse head, with 23mm eye tubes,
    has 100% photo port with no optics above tube lens.
  
  
  
  50mm photo tube too tall for parfocal DSLR:  fixed
  
  
• Alternate Ergo head, with 30mm eye tubes, leaves 80% prism in photo port...
  
  
• Another Ergo head with 23mm eye tubes also leaves 80% prism in photo port:
   
      better condenser, poorer diascopic illumination than Biophot/Metaphot

  Images comparable to those from Metaphot with infinity heads:
  
    CF Plan 20 BD

  
    Meiji 20 has some geometric distortion and focus nonuniformity

  
    CF Plan 20 EPI

• UM-2 measurescope with Optiphot style nosepiece, hacked for EPI DIC