Reducing Video Flicker When Using LED Panel Lighting
Another of my occasional 'no machining' videos: This time I address the flicker I was sometimes seeing on my recordings, particularly on those shots which are subsequently sped up. Flicker may not be the right word, but I'm not sure in this context that 'hum-bar' is either, so I'll stick with 'flicker'. Anyhow, this is something that I first came across back in 2018 ( • Workshop LED Panel Light Build Part 2 ) so this is a bit of a re-visit to that topic.
During the course of making this film I have come to better understand why the 'flicker' looks the way it does (in particular why I see narrow bands across the frame, not a whole field brightness change), which is related to the rolling shutter on my CMOS camera. It would have been interesting to compare the effect against a global shutter (CCD) camera, but I don't have one to hand. Some high end CMOS cameras now implement global a shutter arrangement to help minimise rolling shutter artefacts, but it will be a while before this technology filters down to my price bracket. Hopefully I've proven that a handful of electrolytic capacitors can mitigate the problem for my modest needs.
This isn't the film I'd planned to be publishing in summer 2022, but one or two niggles in the workshop made it feel that it would be worth the effort to pause the project I was on with to try to sort them out...
The first niggle was reducing the to-and-fro rock on the lathe, and was covered in a recent pair of shorts ( • Threading With a Homemade Tailstock D... and • Milling a Radius Without a Rotary Tab... )
The second was the flicker issue. Hopefully with it now resolved, I can get back to finishing what I was part way through making. Unless something else crops up 😉
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If anyone would like a bit more information on the instantaneous frequency wobbles present on the mains, this makes interesting reading: http://mainsfrequency.uk/
For a little bit of further reading on rolling versus global camera shutters, and the artefacts they can generate take a look here: https://tinyurl.com/3p47ks83 and https://tinyurl.com/wbd6y8yy
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Manually subtitled for accuracy: click the CC box
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