3D-printed Light Projector Project

There are things called "Go-Between Objects" or "Gobos" in photography. As this Google search shows, they go between the light (sun or flash) and the subject, cast shadown, and make the picture look more intesting. I was playing with baskets and blinds as Gobos at first. Then I realized I should be able to place a slide and a lens in front of a flash to cast any pattern of shadow or even images. I also remembered there was such a product called Light Blaster already. But I decided I should take it on as my own 3D printer project.

Results

First, here are the results. I brought the whole rig to Norway and took these photos while waiting for the northern lights to show up. "Happy Holidays!" is projected on the side of the bus by the rig on the tripod on the left. Another version is here. The idea was to take the holiday photo with with the northern lights behind us but unfortunately the lights didn't stay visible long enough for us to do that.


Here is Risa's photo from Singapore projected on the San Jose City Hall building.


These are from photo shoots at San Francisco City Hall.



The rig

What I needed was a slide (or transparency), a lens, a flash, and something that will hold them in place. Luckily, a friend was clearing his studio and I was able to get two Canon FD lenses from him. The flange focal distance for Caon FD-mount is 42 mm. So I needed to hold the slide at 42 mm away from the lens and shine the flash from behind. I had recently switched my modeling software from SketchUp to Autodesk Fusion 360 and this was a perfect 3D-printer project for it. After a few tries, I manage to print a body that directly screws into the lens mount.


I picked some of my favorite images and ordered slides from GammaTech and ColorSlides.com (both about $5 per slide). The test went well. The image was projected on our wall clearly.


Godox AD200 is fairly powerful for its size. I can project the image on the wall of a big building.