From what I can see the Radian 8mm and Pentax XW-7 are very similar. The specs below.
Pentax XW-7
- 7mm focal length
- 1.25" (31.7mm) diameter
- 70 deg. field of view
- Long 20mm eye-relief for viewing with or without glasses.
- Lens construction: 8 elements, 6 groups
Televue Radian 8mm
- 8mm focal length
- 1.25" (31.7mm) diameter
- 60 deg. field of view
- Long 20mm eye-relief for viewing with or without glasses.
- Lens construction: 6 elements, 4 groups
I guess the proof is to try out both and see what you think.
I am sure someone will let you borrow them to try
