I took the 16" out tonight for about three hours, seeing about 7-10 transparency 6-10 due to some haze about 15deg above the western horizon, I tried out my recently purchased 5mm Celestron X-Cel, I found that with bright objects like Venus and Mars there was annoying internal reflections, the views of Mars were not as sharp as as in my 7mm Celestron Orthoscopic, but the eyerelief is much greater in the 5mm X-Cel, I also found that at certain angles I was getting some glow from bright Mars behind and to the right of me when I was looking to the south, I had to cup my hand to the side of my face to cut this out when I was looking at faint galaxies.
This eyepiece is brilliant for galaxies, at 365 X mag it was a pleasure to view faint galaxies for S/N, much more easy on the eye than the 7mm Ortho, and there was lots of detail in quite a few galaxies, Ngc 1365 was a treat with both spiral arms and most of the stars in the galaxy that are on the Thompson Supernova Search Charts where seen.
I will be only using this eyepiece for looking at faint stuff in the future, and use the Ortho for looking for detail on Planets.
I bought the X-Cel from Darren (dhumpie) and I think it was overall a good investment.astroro