Pentax premium spotting scopes adhere to the American standard of 1.25" eyepiece thread diameter, facilitating the use of eyepieces from independent manufacturers. That also means, of course, that the wonderful Pentax eyepieces can be used in other telescopes and spotting scopes which accept 1.25" eyepieces.
Pentax eyepieces are a near consensus choice amongst serious amateur and professional astronomers as the best that's out there, quite an accomplishment indeed given the fervent passion of the collective.
The XF lineup are less costly options which were designed for the PF-65ED and PF-65EDA midsized class of spotting scopes and their somewhat shorter focal length of 390mm. They can be used with any Pentax spotting scope, as well as with other telescopes which accept the standardized 1.25" eyepieces. The XF eyepieces are meet the J.I.S. "Class 4" standard for waterproofing, described by the Japanese regulators as "water splashed against the enclosure from any direction shall have no harmful effects".
| Magnification | 32.5x (with the PF-65ED) |
| Angle of View | 1.8° (with the PF-65ED) |
| Field-of-View (@ 1000 Yds) |
93' (31 m at 1000 m) (with the PF-65ED) |
| Exit Pupil Diameter | 2.0mm (with the PF-65ED) |
| Eye Relief | 18.0mm |
| Relative Brightness | 4.0 (with the PF-65ED) |
| Twilight Factor | 46.0 (with the PF-65ED) |
| Weatherproofing | Water resistant |
| Dimensions | 1.7 x 3.1" (43 x 78mm) WxH |
| Weight | 0.34 lb (155 g) |
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Comments about Pentax SMC XF 12mm Eyepiece (1.25"):
I bought this eyepiece after returning an XW 14mm. I prefer the ease of viewing, more manageable field of view, natural-sized eye lens, and equal sharpness and contrast (to my eye) of the XF12. The field is wide enough so that the field stop is out in the periphery, so if there is any loss of image quality at the edge, I'm unable to notice when using it. I own two pairs of Nikon Premier LX bins, so am used to a nice view.
The eye lens is fairly deep-set, so the eye relief is just adequate with my glasses (glasses need to be touching the eye cup). Otherwise couldn't be happier.
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