I am building a camera obscura that will be used as a screening room as opposed to making large images with. My brightness needs to be superior because the imagery being captured in the camera will be a live performance that viewers observe from inside the camera. The obscura is going to have an 11 foot focal depth. I am curious to see if anyone has any insight on what kind of lens might help with this. I have contacted an artist who is doing something similar but he is taking some time to get back to me. He seems to be using something that exceeds 1000mm. Any ideas would be greatly appreciated!