APUG member Murray@uptowngallery installed a camera obscura in a large room at the Holland Area Arts Council. He needed to black out several very large windows then make his "lens." The image is projected onto large side and end walls.
I am quite familiar with the principle, but have never had the opportunity to see one in use. Very interesting and informative. Kudos to Murray for demonstrating a part of the history of our art form.
I used a variable aperture from Surplus Shed as it was my first attempt at this.
A black-painted open-joist ceiling and blacked out glass doors & sidelite windows reduced the straight-on image of a large bank building and fountain. So much of the image that is most visible is at large angles. This creates some interesting 'tilt' distortion, as it were. Cars driving by seem to have what looks like a 'visual Doppler effect'...the car's speed speeds up as it passes by. Cars also seem to circle the room from one side to the front to the other side.
A 'portable' L-shaped display wall was angled to catch separate illumination from a 57 zone zone plate optimized for 4 meters (13 feet), made for me by a friend in France.
I had to set things up to see what would work where...unfortunately the Zone plate display wall is directly in front of the main aperture, so the L-shaped wall was positioned to 'block' the Zone plate from one side, and catch one half of the side angle of the main aperture.
This way, the bank's flag is visible on one bright white wall, fluttering in the breeze.
The tree and cars directly in front of the aperture are slightly bigger than 1:1 macro.
I'll see if I can catch anything with a 01100111111000 camera because I don't have time for the learning curve of setting up a film camera a la Abe(lardo) Morell.
I never even though about my cell phone camera...hmmm...
Yes, but with a lens, and I couldn't get far enough back to see the full room view. The portable wall was about 13' from the window. The dimmer wall didn't record any image at all.
So I have alot of angular distortion...and the frame is so full it's hard to get perspective...ok for a first try.
I did 100 units of brightening (on a scale of 127) in GIMP. I don't know how many 'stops' that would be equivalent to...
I can't say that I've really got an understanding yet of just what it is we're looking at. The image I saw didn't look like a zoneplate image, and I'm not sure what you mean about the zone plate display being "blocked" etc. Now, did you use a lens that also had a 4 meter fl to make the image I saw?
The building depicted in my 3rd thread post above is a bank directly across a 2-lane road from the front window of the gallery.
On the side of the building is an alley/driveway and a building and partial view of the downtown. I placed a 4m zone plate in that window, about f/250.
I was not able to effectively utilize the zone plate (4m = 13 feet) in the room that was roughly 20-24 feet wide. The angled wall was initially placed as a 'half room' to catch the zone plate projection and not interfere with the variable iris presenting the main view.
The picture shown was taken after covering up the zone plate and moving the V-shaped wall directly in front of the main aperture, with the apex (open V) away from the window. A 0.25 diopter lens (also 13'/4m, the initial reason for having a 4m zone plate made) was then placed over the aperture.
So what you see is a flat building folded in the center by the projection onto a V-shaped wall...maybe a bit of "W" distortion because the image wraps around the outer edges of the V-shaped wall.
The camera was about 10-15 feet from the vertex of the V at roughly 30-45 degrees. It was all a hurried effort to finish up as I had to tear it down & get somewhere earlier than expected.
I had also made an 1.8 m tube with a pair of lenses that I calculated to be about 8m f.l. but it was too unwieldy.
Camera Obscura Installation 
Linear Mode
