I'm still looking foreward to using the 820 despite the mixed reactions!. I usually use 5x4, but I also use an Olympus pen quite a lot. What I was after was a 'vintage' compact camera to use like I use the Olympus,that was easy to use, gave a bigger neg, very easy to carry. With this in mind I thought the 820 would do along with a light monopod, small meter, lens hood and a couple of filters. I could walk for miles with this little set!
I'm still not 100% sure of the filter size although I reckon its 42mm push on. I'm not really into collecting vintage stuff to display, I'd much rather use it, so I'll have a look at the lens front after my hols and perhaps epoxy a ring on the front (if it will still fold up) that will use the large amount of 49mm filters / hoods I already have. If I can't do that, then who knows!. Some of this vintage stuff is maddening!