Pentax Eyepiece SMC XW40-R 40mm 2" (64635)

The Pentax SMC XW-Revival eyepieces, specifically the XW-30 and XW-40 models, are designed for astronomers who want high-performance optics and comfortable viewing during long observation sessions. These eyepieces use high-refraction, extra-low-dispersion lanthanum glass elements to deliver sharp, well-balanced images with minimal aberrations. The optical design is optimized to reduce the blackout effect by compensating for the spherical aberration of the pupil. With a wide 70° apparent field of view and 20mm eye relief, these eyepieces provide clear and immersive views, making them ideal for observing nebulae, star clusters, and other deep-sky objects. The weather-resistant construction allows for reliable use in outdoor conditions, although they are not intended for underwater use.

Main Features:

• Long focal length, suitable for observing nebulae and star clusters

• 70° apparent field of view and 20mm eye relief for comfortable, wide-angle viewing

• High-quality optics with high refractive index, ultra-low dispersion lanthanum glass elements

• Multi-layer coatings for excellent light transmission and image brightness

• Advanced light-shielding technology to improve image contrast

• Weather-resistant design (JIS Class 4) for all-weather use

• Rotatable, adjustable eyepiece cup for added comfort

Compatibility:

• Fits telescopes with a 2" (50.8mm) sleeve size

• Not compatible with Pentax spotting scopes, which use a 1.25" (31.7mm) sleeve size

Specifications:

• Focal length: 40 mm

• Apparent field of view: 70°

• Eye relief: 20 mm

• Number of lenses: 6

• Number of groups: 5

• Telescope connection: 2"

• Camera end connector: M48

• Coating: Fully multi-coated (FMC)

• Light transmission: 96% at 550 nm

• Field stop: 46.5 mm

• Adjustable eyepiece cup: Yes (rotatable)

• Optional camera adapter: Yes

• Filter thread: Yes

• Inert gas charge: No

• Series: XW

• Weight: 700 g

• Length: 117 mm

• Diameter: 76 mm

• Type: Eyepiece

• Build: Super Wide Angle (SWA)

These eyepieces offer advanced optical quality, wide-angle comfort, and durable construction, making them a reliable choice for serious visual astronomers.