Is it possible to use filters on the supplied Sony wide0angle adapter that is included with the PD170. There seem to be no threads on it and I believe (correct me if i'm wrong) the diameter is 93mm. Would I have to use a mattebox in order to use filters with this adapter and if so, what kind?
Thanks!

Century makes a lens shade/filter holder which I'm using on my Z1 with Century lenses. It clamps on to the outside of the lens and doesn't need threads. Not sure what the diameter is offhand, but might be worth checking out. It's much cheaper than a mattebox, and in fact century was offering for a low promotional price recently. I couldn't find it on the Century website, so you might need to call or e-mail them. I believe they make a couple different versions of the same product - one of them may fit your lens.

Here's a link to the Z1 version on the B&H site:

http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=376587&is=REG&addedTroughType=search

Contact Century here: http://www.centuryoptics.com/contact.htm