At a Glance
5mm
Focal Length
70°
Apparent FOV
20mm
Eye Relief
1.25"
Barrel Size
Score Breakdown
Overview
The Pentax XW 5mm is a high-end eyepiece built for observers who want genuine quality at the demanding short end of the focal length range. At 5mm, this is a high-magnification eyepiece, best suited for planetary detail, double stars, and globular clusters when seeing conditions allow. What sets it apart from budget options is the combination of a 70-degree apparent field of view and a generous 20mm of eye relief, which is unusually comfortable for an eyepiece this short.
Many high-power eyepieces force you to press your eye close to the lens, making extended viewing tiring. The XW avoids that problem. The lanthanum glass elements keep color fringing and edge distortion well controlled, which matters at this focal length where optical flaws are most visible. The fully multi-coated optics help maintain contrast and light transmission, important when you are trying to resolve fine detail at high power.
At $314, this is a significant investment for a single eyepiece. It is aimed at observers who are serious enough about the hobby to want optics that will not be the limiting factor in their setup. The weatherproof body adds durability for those who observe in variable conditions.
Key Features
- 70-degree apparent field of view gives noticeably more sky context than typical high-power eyepieces
- 20mm eye relief remains comfortable for eyeglass wearers even at this short focal length
- Lanthanum glass reduces chromatic aberration and keeps edges sharp across the field
- Fully multi-coated optics improve contrast and light throughput for demanding high-magnification targets
- Weatherproof construction handles dew, humidity, and field conditions without concern
- Well suited for planetary detail, double stars, and tight clusters when atmospheric seeing cooperates
- Premium build quality justifies the price for observers who want optics that match a quality telescope
Specifications
| Focal Length | 5mm |
| Apparent FOV | 70° |
| Eye Relief | 20mm |
| Barrel Size | 1.25" |
| Design | Wide Angle |
| Elements/Groups | 7/5 |
| Series | XW |
| Coating | Fully Multi-Coated |
| Waterproof | No |
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Amazon Reviews
Very nice eyepiece. Clear and sharp. NOTE: eye relief is not really enough for eyeglass users. I always removed my glasses to use this Pentax eyepiece.
This is probably one of my favorite eyepieces. It’s great for those not wearing eyeglasses at the eyepiece. Fantastic contrast and objects look fantastic through it.
Great optics with a moderately wide field at a lower price than some of the competition. However, for me eye placement is critical to avoid the kidney bean effect. The adjustable eye cup is helpful in getting the eye position right. I use a 5mm Nagler, bought used, for outreach, as the eye position ...
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