Sorry for answering late, I have been away. I could not find any information concerning the shutter diameter for the front mounted shutter model. I bought one, it should be delivered nest week, and I will measure and post the size of the opening. On the rear mounted shutter of the folding model, shutter size must be relatively close to 13x18/5x7, as shutter and film plane are quite close together.

The idea of an LCD shutter sounds fascinating.