Gas station without pumps

2020 July 10

Ring light for iMac

Filed under: Circuits course — gasstationwithoutpumps @ 08:19
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I was having some trouble using the green-screen capabilities of OBS, and the videographer who works on online courses for UCSC suggested trying a ring light behind my iMac to get more light on my face. I decided to make a ring light and see if it helped.

On Wednesday I walked to my dentist appointment, rather than bicycling, so that I could stop by Palace Arts on the way home to pick up a piece of foam core to make a frame to tape to the back of the iMac, without blocking any ventilation ports.  I already had strips of LEDs that I could use to provide the light.

Here is the layout of the ring light, seen from the front, before mounting it on the iMac.

The hinge (made by scoring the foam core and then crushing the foam slightly at the score line) allows the monitor angle to still be adjusted, even with the foam core taped to both the stand and the back of the computer.

Here is the ring light attached to the back of the iMac with blue painter’s tape and lit up.

The ring light was not difficult to make, but it did not do what we had hoped. It does illuminate my face a bit more uniformly, but the camera in the iMac automatically compensates for the extra light, resulting in the green-screen background looking olive drab and being even harder for OBS to use in chroma keying. It’s too bad that OBS doesn’t have Zoom-like background elimination, which can handle a much wider variation in color and lighting of a green screen. The ring light also does not work well with glasses, as there are two really annoying reflections of the light off the front and back surfaces of my glasses.

So I wasted a day experimenting with the ring light. My next attempt at improving the green screen will be to mount a strip of LEDs at the bottom of the cloth screen, to see if I can erase some of the shadows there and get more uniform and brighter lighting of the screen.

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