Pentax XW 3.5mm 1.25" 70° Telescope Eyepiece

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Pentax XW 3.5mm 1.25" 70° Telescope Eyepiece

The 3.5 mm XW, 1.25-Inch Pentax Eyepiece, like each eyepiece in its series, the XW 3.5 eyepiece is designed specifically to provide ideal ground and astronomical observations with a telescope

Key Features

70° Apparent Field of View & 20mm Eye Relief

All smc PENTAX XW-series eyepieces feature an extra-wide 70-degree apparent angle of view and an extra-long 20mm eye relief to deliver an exciting, wide-perspective image. If you look at the simulation to the left, you will notice that the images have the same magnification, but the Pentax XW eyepiece has an increase viewing area.

Pentax XW 20mm eyepiece Apparent field of View Simulation

Pentax XW 20mm Field of View

Standar Plossl 20mm eyepiece Apparent field of View Simulation

20mm Plossl Field of View

*Simulation based on 8" f/10 SCT

Pentax XW Optical Coatings

High-Grade Optics

The high-performance XW-series optics incorporates high-refraction, extra-low-dispersion lanthanum glass elements to produce a well-balanced image with minimal aberrations. These eyepieces were designed to reduce the disturbing blackout effect by compensating the spherical aberration of the pupil.

All lens surfaces that come in contact with air are treated with the original multi-layer coating, while all laminated surfaces are treated with the 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

The XW series features JIS Class 4 weatherproof construction,* making it possible to use it in drizzle or under night dew.

* The XW-series eyepieces are not designed for underwater use and should not be submerged under water.

Pentax XW Weather Proof Eyepiece


ER20mm or More
Eye Relief20mm
Eyepiece Diameter61mm
Eyepiece Length137mm
Eyepiece TypeFixed
Eyepiece Weight0.89lbs
Field of View70 Degrees
Focal Length3.5mm
FoV 79 Degrees
Customer Reviews
5.0 Based on 1 Reviews
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Planetary Gold

This EP will give you the absolute BEST planetary views you will ever see. I've gone through a dozen or so high magnification Eps and none of them performed nearly as well as this 3.5mm. I'm talking about major, well-respected brands that could not match the Pentax performance. I now own 4 Pentax XW's, including the 30mm, 20mm, 14mm, and 3.5mm. These come with a limited lifetime warranty from Pentax, they are weatherproof, and they have crisp, bright, high-resolution images that will blow you away. You cannot find a better eyepiece, period.