SteveInNZ wrote in post #15824551
You might want to Google "Harris Shutter" which is the technique you're describing.
Sounds like fun. You should give it a go.
I've seen them before. But I didn't have a name associated with it since it was a couple decades ago. With a name (thanks) Google pulls up a lot more. But like what I saw in the past, these are overly "crisp". I'm wanting a more subtle look where instead of stark red, green, and blue, I get smooth shades of color. That is the hope with the longer exposures.
I tried these tricks with multiple exposure in a film camera with gel filters many years ago. One involved lightning shots (red, green, and blue strikes). That's where I decided I needed to find a way to avoid the stark red/green/blue issue. But working with a film camera that had to be manually re-cocked while holding another lever to avoid advancing the film did not work to well as the film did juggle just a bit and alignment was lost. This was back in the day when the first Mac came out in black and white, and I did a trick that made them come out in color under a triple RGB exposure. It still had the alignment issue and unfortunately most of the film work back then was lost.
One effect that could not have been (easily) done on film was the black and white variation. In digital PP you just make the shots into black and white first, then do the mix into color channels. To have done that in film would have been "labor in the lab".
I guess now armed with a name, I should re-do some and start its own thread under that name ... though ones with welding glass or other ultra-ND long exposures could come back here.
Update: I started a thread for the color effects: https://photography-on-the.net …/showthread.php?t=1291727