I understand that the 50mm lens is smaller than a 2" filter but I can think of a number of ways that threads could be put at the opening of the aperture to accommodate 2" filters. I have Aperta's 2" filter adapter for the S50, AND IT SUCK GREAT GREEN GANGRENOUS DONKEY DONGS!!! If you don't read the little print on the outside and try to shut the arm with it in place the gears will grind horribly when the filter holder can't clear the bottom of the housing. Tired, late at night? No excuse. Remember or damage the unit. And if you remember as it's shutting down and run to take it off, well good luck with that tension housing while the arm's moving. If you do manage to get it off in time, odds are good that the metal filter housing will smack the lens. Even once will scratch/nick it. That ring on the Aperta filter holder seems to serve no purpose but to introduce one big hassle in what is otherwise a very hassle free telescope. But that goes back to why such a crap accessory even exists. Because you can't directly thread filters into the aperture. And threads would be SO much better than the current, "just shove it in tight" followed by removing its "now pry it out". I think the S50 is a brilliant revolutionary product. I am shocked that with so many smart ideas in one package that the filter end of things is so slap-dash.
And, ideally, could you introduce your own accessory that accepts 2" filters and actually fits the aperture? It still would have that lousy tension secured housing, but at least you won't destroy the gears if it's 5am and all you're thinking about is getting to bed. A cancel button on the shutdown would help all that too, but I can understand that that probably isn't a straight-forward or viable thing to do, interrupting the shut-down sequence.
