The Pentax SMC 8-24mm waterproof Nitrogen filled zoom is excellent!!
I bought, used and resold many (Moonfish, Baader, Meade, TV) before I had the opportunity to buy this Pentax.....
I use it for solar observing with the ED80/SM60 and the 102/ PST Mod - no need for anything else.
http://www.bhphotovideo.com/c/produc..._Eyepiece.html