I already had a pair of 12 mm XFs for my binoviewer, and the 8.5s are every bit as good. Lousy weather recently, but I have been able to resolve lunar objects down to 6 miles across so far, and with better seeing I am confident I'll get more detail. Excellent value.

I got this eyepiece as a start to upgrading my EP set- mostly Skywatcher stock EPs and some Celestron. I also wanted to see how Pentax did Astro lenses. The 8.5mm XF is a very fine EP. It’s very nicely made with very good twist-adjustable generous eye relief and very sharp images. After the performance of the XF, I didn’t hesitate to start my EP upgrade with Pentax.
I now have the XW 3.5,5 and 7mm but always start my observing session with the 8.5mm - there’s little difference to me in the quality of the image against the XFs. If seeing is marginal, I’m more than happy to stay with this EP only. It also Barlows up very nicely if you are using small/mid-size focal length tubes. I had a stunning view of Saturn with a 2x Celestron Ultima Barlow in my 6in 750mm f5 Reflector (176x). It is a good lens at the faster focal lengths where some EPs can be a bit soft on focus.
It will always be in my EP collection.

Tried on a VIXEN BT81S-A bino-telescope, and compared to VIXEN's LV10mm views of the moon are crisp and clear. Mars can be observed with the limitation of the low magnification (given by the bino-telescope). Eye relieve is convenient and the eye-guard very practical. These EPs are very well made (fit and finish) and optically perform very well. On my bino-telescope, magnification is x56, far above the maximum magnification recommended by the manufacturer (x48) but I cannot see any severe degradation. For the price... you will not find anything better.