I have this camera and love it. Lens is quite sharp, too.
There are filters you can get for this camera, that were made for it...rare and -- you guessed it -- expensive.
Check fleabay to have a look, there's usually some up there. Or call on Mr. Google.
It's a good idea to exercise the shutter on this camera -- you can pull the lens turret back and let it go just to keep things greased up. Actor/El Duderino Jeff Bridges has a cool page on his Widelux work, with some good advice on it.