Sure, you will have copyright on the design of the booth, but not over the pictures it takes. And you will have copyright over photo's that have custom frames that you've created. The picture then becomes a derivate work with one part beging public domain and the other is your work. (Your frame.) If I would create those frames, copyright would be mine, too. Because I created the frame and you just made the derivate work. You would need a license from me in that case.
And the creativity of the participant will also be quite low in general, unless they're going to do a real strange pose, wearing make-up and clothes especially for this picture. But if they would just walk around dressed as clowns and just have their picture taken then it's not much creativity. Most likely not enough to claim copyright. Their appearance is a creative choice, the fact that they had their picture taken is not. Anyone with a camera could take pictures of them without having to give them copyrights just because they've dressed in a creative way.
However, the personalities will have a different right called Personality Rights. (http://en.wikipedia.org/wiki/Personality_rights) This might limit the things that can be done with those pictures. You might, for example, use them with a newspaper article or display them in your shop. But you might not use them for e.g. a dating site or other commercial purposes without the participant agreeing with this purpose. But the picture itself is still public domain.
Also, it makes not much difference if you're continuously filming or just have a shutter open and close. Filming might actually make it even less creative, since it would be like a surveillance cam.