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Pentax XW 20mm 70° Telescope Eyepiece - 1.25"


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Product Details

  • The 20 mm XW, 1.25" Pentax Eyepiece, like each eyepiece in its series, the XW 20 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 similuation 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
  • specifications

    Eye Relief20mm
    Eyepiece Diameter61mm
    Eyepiece Length86mm
    Eyepiece TypeFixed
    Field of View70 Degrees
    Focal Length20mm

Product Reviews

Customer Reviews
4.8 Based on 6 Reviews
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    Ales P.
    Pentax XW Eyepieces in professional use.

    As a lens and scope designers and manufacturers we need the very best eyepieces to test our optics with. This is why I’ve personally chosen Pentax XW series eyepieces after giving all other brands a fair trial over the past few years. Optically, these are the best performing eyepieces on the market today. Also the mechanical design and quality of build easily outperform even the most expensive eyepieces available. These wonderful eyepieces are moderately priced so if you are looking for the ultimate quality to match your objective lens with, look no further. I did the same thing and I couldn’t be more satisfied. Remember that a superb quality objective lens or mirror represents only half of your optical system. Never save money on what is the most important part of your scope! Ales Patrick Krivanek ISTAR Optical, owner

    Perfect balance

    The XW series are must have eyepieces for people who want a perfect balance between all design factors. In my C11, it is simply the finest all-purpose ep giving 140x. No one that I know of argues with Pentax's superior contrast, through-put and sharpness. I personally prefer a perfectly flat field to one with distortion, so I get a little field curvature, which seems rather slight at the outer edge. I suppose that since my C11 is on a driven eq mount that I don't notice the field curvature. Truly pinpoint stars and lovely neutral coloring of objects is very pleasing. Truly an all-purpose ep for planetary and deep-sky work. Add-in the flamboyant eye-relief, (hot, sweaty evenings and cold winter nights will no longer hamper you with fogging lack of kidney bean and a twist-up eyecup and you'll be a proud owner. Barlows very well with my 2x Celestron Ultima barlow yet another bonus. As a side-note: you will be hard-pressed to really see a difference between the XW's 70 degree AFOV and that an 82 degree ep. I have owned and used many ep's and the total comfort afforded by the XW will definately enable you to stay at the eyepiece longer.

    Pentax 20mm

    I have the full set except for the 30mm which I will be adding. The best performing are the 20mm and below with the ones 10 and below at the peak of best eyepieces I have used/owned. The 20 just starts to have a bit of edge softness but not enough to be an issue....the 40 likewise is a bit softer on the edges BUT after using Panopics, Naglers and recently Ethos...I find that the Pentax are the most user friendly...they are VERY comfortable to use for long period of time, don't have annoying characterists like kidney bean shadeows. I have 2 11 SCTs, 85mm APO, 105mm APO and 152mm APO refractor and find that in every case the first eyepiece I grab is the 20. The only other that gets as much use is my Pentax 8-24mm Zoom which is a fabulous eyepiece. That one works fantastic as long as you don't have an extremely fast f stop. In addition the zoom is my favorite Ha solar eyepiece...easily beating my dedicated Coronado solar eyepiece collection...go figure! That zoom is spectacular with my APO refractors. It lets you fine tune the background dark and FOV to bring out detail you usually miss with other fixed focal length eyepieces. I sold all my other eyepieces (mostly TV and have never regretted it. Only TV I would own now would be an Ethos which I have used quite a bit and it is amazing.

    Robert H.
    Very good, but better at longer focal lengths

    This eyepiece is an unqualified success in so many areas: construction, fit and finish, ease of use are all top notch. This is the most comfortable eyepiece I have ever used, the eye relief is very generous and not picky about eye placement. The twist-up eyeguard works great. The 70 degree AFOV is immersive, if not quite up there with a nagler. Contrast is simply amazing, in my light polluted backyard the sky was obviously darker than with my 20mm plossl eyepiece. I could see the star at the center of the Blinking Planetary nebula for the first time. I think the contrast is the strongest feature. But.... Field curvature. It is always there, and it is enough to be bothersome. In my 80mm f6.5 refractor, it is objectionable, the outer third of the field is very soft. In my 8 F10 SCT, it gets better, but still about 25% of the field. Barlowed at 2x, it becomes hard to notice. But it is frustrating in a high end eyepiece. I'm not sure if I would buy it again, but having bought it, I am very happy with it and it is my most frequently used eyepiece, despite the field curvature. All the other positive features make it worthwhile.


    Ditto I have to concur completely with the above review. I have owned Panoptics, Naglers, Radians, Meade Ultra Wides and for my style of viewing this eyepiece is heads and shoulders about the rest. It is exactly the right combination of magnification and field of view in my Televue 102. 90% of my viewing is with this eyepiece. It comes with a bolt case which I was very impressed with.

    My favorite eyepiece

    After looking through dozens of different eyepieces of all makes, models, and focal lengths over the years, I keep coming back to the Pentax 20mm XW. Stunningly well corrected in my 12 f/5 dob, this eyepiece is also the first one I grab for my 4 f/8 Apo. Patented Pentax design and coatings yeild massive amounts of contrast and pinpoint stars across the field.