“A terrible idea that should never have been tried!” – Ansel Adams, April 2021.
This image is captured by shooting the film back of a Brownie 620 camera using a Raspberry Pi camera mounted inside the black chamber above the lens just outside the optical path. High gain screen material is used on the image plane to maximize the reflected light. It works, sort of… The current limitations are that it ends up being very low light so in full sun, I have to use the highest ISO available and about a .25 second exposure. Also, since the sensor is not in line, the captured image is skewed and you end up with soft focus on the top and bottom.
First image, un-warped and brightened.
It’s a fun project, and I’m sure I’ll complete it someday. I am waiting to see if a higher sensitivity chip will become available for the RPI. Ultimately, the best solution would be to manufacture a lens element that would refocus the 120 film size beam onto the small sensor mounted in the back, or a concave mirror on the back that would reflect the image onto the sensor where it is currently mounted (both of these solutions are beyond my pay grade).
This uses a Raspberry Pi Zero W and a small LCD panel, both powered by a Pi Sugar battery. Operating system is diet pi. The camera is operated with the buttons on the LCD panel board and the resulting image is displayed on the screen. Using VNC and a virtual desktop, I also get the live feed directly from the camera to a laptop. The pictures are saved with the raw information and converted to DNG. I designed a 3D printed adapter to mount the electronic components on the body of the camera but I am waiting on more light sensitive solutions to finish the piece.