40mm Pentax XW - My Review

The awesome 40mm Pentax XW !!!

I was lucky enough to borrow this from a very good friend and astronomer John G. (Thanks so kindly John!). He's definitely the NICEST person I have ever met and has loaned me a few eyepieces to try out, (Thanks again John!).

I have always been very curious about the 30mm XW, but he didn't have a 30mm XW.... He did however have the 40mm XW ! The exit pupil is rather LARGE when using this in my 10" F/4.7 Orion Intelliscope, but I thought I would give it a try regardless because of the excellent reputation the Pentax XW's have. In the past I have owned the 5mm, 7mm, 10mm, 14mm and 20mm XW's. My faves were the 7mm, and 10mm versions.

I drove about 30 minutes away from the city to a fairly dark spot for my initial testing on November 8, 2022. The sky was really nice with the Milky Way almost overhead at the time. I tested it on M-45, IC-4665 and later on in late November on M-41. It was excellent on M-45 in Taurus and IC-4665 in Ophiuchus. I compared it to my 21mm Hyperion and 14mm FTR on M-41, and I preferred the view in the 21mm Hyperion as it looked "washed out" on M-41, which is to be expected in the city, in light polluted skies.

Overall correction without a coma corrector was extremely good from what I could see. I was really surprised to see this as I expected it to show a bit of field curvature. There was none to be seen. Eye placement was very easy as well. I tried it with my Lumicon UHC and DGM NPB filter, (The NPB is owned by John), and it played well with filters too.

I have owned the 30mm APM UFF a few times, but I am curious to see how the 30mm XW would fare in my telescope. I am hoping to pick one up soon to try out. The 30mm would be better with a smaller exit pupil for my particular telescope at 6.35mm as compared to the 8.5mm exit pupil with the 40mm XW.

That's it for this review!  I hope you enjoyed reading it. I can say In highly recommend the 40mm Pentax XW!

Clear and Dark Skies to All !!!

-Mark