About 25 years ago I took a class through Montana State University in Bozeman called "The Physics of Photography." The class was quite enjoyable and as part of the course I ended up with these 2 plastic cameras. Since I've been into shooting my Minolta 16P I thought I'd pull these out and play with them a bit. I did a quick test with the Yunon one, shooting Kentmere 100, setting the aperture to 8, 11, and 16 for various shots, and developed in D-76 stock, 10 minutes at 72 degrees F. I didn't see that much difference in the negatives. Here a scan of one of them and a photo of the cameras.