Pentax 20mm XW Eyepiece - 1.25"

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Pentax 20mm XW Eyepiece - 1.25"
Item # PE-XW20
  • This Pentax XW Series Telescope Eyepiece is presented in a 1.25" barrel format with a 20mm focal length.
  • Crafted with high-refraction, low-dispersion lanthanum glass, the Pentax 20mm XW eyepiece delivers bright, high-resolution images with minimal aberrations and distortions.
  • This Pentax XW Series Telescope Eyepiece has an Apparent Field of View of 70 and Eye Relief of 20mm.
  • Advanced computer simulation design technology implemented to drastically reduce internal reflections, producing brighter, clearer images.


Pentax 20mm XW Eyepiece - 1.25"

The XW 20 eyepiece is designed for use with a wide range of PENTAX spotting scopes and telescopes. Ideal for both ground and astronomical observations, this eyepiece features fully multi-coated lenses to increase light transmission and color quality, high-refraction lanthanum glass elements for high-resolution images with minimal aberrations, and JIS Class 4 weatherproof construction for durability. Engineered using advanced computer simulation design technology, this high-performance eyepiece provides a 70 degree field of view and 20mm eye relief.

Compatible with the following: PF-65 and PF-65 ED II series spotting scopes, PF-80 series spotting scopes, PF-100 series spotting scopes

Pentax 20mm XW Eyepiece - 1.25"

  • Improved 70 degree field of view for wider views
  • XW 3.5mm, 5mm, 7mm, 10mm, 14mm, 20mm, 30mm, and 40mm provide a wider field of view than previous PENTAX eyepieces
  • All Pentax XW series eyepieces may be used with astronomical telescopes with appropriate 1 ¼” or 2” focusers.
  • XW 3.5mm, 5mm, 7mm, 10mm, 14mm, 20mm eyepieces may be used with our PF series Spotting Scopes (except PF 63 Zoom)
  • Full multi-coated lenses increase light transmission and contrast
  • High refraction, extra-low dispersion lanthanum glass elements deliver bright, high resolution images with minimal distortions and aberrations
  • Advanced computer simulation design technology implemented to drastically reduce internal reflections, producing brighter, clearer images
  • Weatherproof construction for greater durability
  • Long eye relief for comfortable viewing with or without glasses
Pentax Product Number: 70516
Additional Information

Additional Information

Manufacturer Pentax
Optical Design Wide Angle
Barrel Size 1.25"
Warranty 1 Year Warranty
Eyepiece Field of View - Apparent 70º
Eyepiece Focal Length 20mm
Eyepiece Eye Relief 20mm
Eyepiece Manufacturer Series Pentax XW
Eyepiece Weight 12.6 oz.
Field Stop 24mm
Number of Lens Elements & Groups 7 elements
Special Feature None
Comes with Dust Caps? Yes
Comes with Eye Guard? Yes

Customer Reviews 6 item(s)

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
1= Houston, We Have a Problem & 5= It's Out of This World
Review by Ales P Krivanek / (Posted on 1/10/2013)
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.
1= Houston, We Have a Problem & 5= It's Out of This World
Review by JCM / (Posted on 6/2/2009)
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.
1= Houston, We Have a Problem & 5= It's Out of This World
Review by RKB / (Posted on 12/27/2008)
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.


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.
1= Houston, We Have a Problem & 5= It's Out of This World
Review by Robert Harris / (Posted on 10/10/2007)
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.
1= Houston, We Have a Problem & 5= It's Out of This World
Review by / (Posted on 7/22/2007)
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.
1= Houston, We Have a Problem & 5= It's Out of This World
Review by HC / (Posted on 7/18/2007)
Included Items

Included Items

  • Pentax 20mm XW 1.25" Eyepiece
  • Eyepiece Case
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