Pentax 40mm-R XW Eyepiece with SMC Coatings - 2" - 70538
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Pentax XW Eyepiece Series
Featuring functional, practical focal lengths, the Pentax XW weatherproof eyepiece series provides a comprehensive line-up of magnifications that accommodates all types of applications, from low-magnification viewing of deep-sky objects to high-magnification observations of planets.
About the Pentax 40mm-R XW 2" Eyepiece
The Pentax 40mm-R XW eyepiece offers clear, comfortable viewing, with a 70° apparent angle of view and 20mm of eye relief with the adjustable eyecup in its lowest position. With a twist of the light-shield, you can place your eye at the best position for comfortable viewing that still offers the best contrast.
Thanks to its long focal length design, when mounted to an astronomical telescope with a focal length of 1000mm or less, the XW40-R eyepiece will let you observe large deep-sky objects in their entirety. Objects like the Pleiades star cluster or the Andromeda Galaxy are so impactful when seen with the surrounding night sky around them!
This focal length eyepiece has a 2", or 50.8 mm, installation barrel. The top of the eyepiece also has a screw thread with a 43mm diameter and a 0.75 pitch when the light shield/eye cup is removed.
Pentax High-Grade Lanthanum Optics for Exceptional Image Quality
The high performance optics used in all Pentax XW eyepieces incorporates high-refraction, extra-low-dispersion lanthanum glass elements to produce a well-balanced image with minimal aberrations. The XW eyepiece is particularly designed to reduce the disturbing blackout effect by effectively compensating the spherical aberration of the pupil.
All lens surfaces that come in contact with air are treated with the original SMC multi-layer coating, while all laminated surfaces are treated with an innovative partial coating to offer the light transmission efficiency of more than 90 percent (an astonishing 96 percent at 550nm) over the visible light spectrum.
Weatherproof Construction for All-Weather Viewing
The Pentax XW series eyepieces feature JIS Class 4 weatherproof construction. While you cannot submerge these weatherproof eyepieces under water, their JIS Class 4 construction makes it possible to use them in drizzle or under dewy night conditions.
Pentax 40mm-R XW Eyepiece Specifications
- Focal Length: 40mm
- Number of Elements/Groups: 6 Elements in 5 Groups
- Apparent Angle of View: 70º
- Eye Relief: 20 mm
- Distance from Rubber Cup: 15 mm
- Barrel Size: 2"
- Length & Diameter: 117mm x 76 mm
- Weight in Grams: 700g