rkelley8493

For a 115 f/7 refractor, a 7mm Pentax XW will give you "Resolving Magnification" where finer details can be seen while keeping an elevated level of contrast. This is where focal length of the eyepiece is equal to the focal ratio of the telescope, and you get a 1:1 ratio with aperture:magnification. If and when you decide to get a Powermate or Barlow, you can double the power and get a 2:1 ratio which is said to be the "max useful magnification" of a scope. I've found the Pentax XW's to be great for all categories of observing; lunar, planetary, & deep sky. They have excellent sharpness, brightness & contrast. Funny thing is, I can a better image when I Powermate a 5mm XW than I do with a 6mm Delos + PM in either of my refractors [SVA130T f/7 and FC-100DF f/7.4]. I'll see how a 7mm XW + Powermate looks compared to a 3.5mm Delos next time out.

Hi Derek. I recently got the same scope and am wanting to upgrade the focuser to a Feather Touch. Which model goes with the FC-100DF? Is it the MPA-TAK2.5 for 2.5" focuser or the MPA-TAK2.7 for 2.7" focuser?