So I’ve started a new Medical Maker youtube channel, and ran into a technical video snag on making the title video with filming slow-motion of high-speed machining. I haven’t tried this in the Glowforge but you may encounter this kind of problem when filming your maker projects:
I hope to get a slightly better audio for the next video.
That flicker would trigger a migraine for me in about 15 seconds - ouch! Good solution!
Slightly askew of the subject but newer still frame cameras (i.e. Canon DSLR’s) actually look for this 60Hz flash and time the shutter release so the exposure is correct.
You are a man of many talents. Now while I don’t suffer seizures from strobes I must admit that part was difficult to watch.
It happens because the flashing of the light source is not synchronized with the camera’s shutter speed. Many light sources flicker, you just don’t notice. Persistence of vision makes flickering faster than about 24 per second mostly invisible (which is why cinema film is shot at 24FPS, it’s the minimum that most people won’t notice). But cameras don’t have PoV. So when the light source flashes at a rate different than the frame rate/shutter speed of the video camera, the two different frequencies “beat”. At times they line up and the shutter is closed before the light intensity drops. At other times don’t line up at all and the shutter is closed when the light is at its brightest. And all the variations in between, too. So on playback, the light intensity randomly changes from low to high at a rate that’s a function of the speeds of the light flickering and the camera’s shutter.
When you shoot high speed, you can’t rely on AC powered incandescent or fluorescent or LED lighting because they all flicker. You need DC powered lights, or a separate strobe light that the camera can trigger, or you need to be outside so that you can use ambient light.
You can, just not the cheap Chinese crap on amazon. I mean patio lighting has no reason to be filtered. All LEDs are DC of course, but the power supply can be cheap switching style or good filtered like in your computer. Dedicated video lights have filtered dc supply. My good led video panels wouldn’t survive 10 seconds in there, but outdoor lighting is rugged and waterproof.
Yeah, it’s hard to do that at 240fps…
You can do some really fun things:
I’ve loved that helicopter one since I first saw it - but that guitar was new to me. SO COOL!
and yeah - ab fab that something as simple as a big bright flashlight to fix the flash issue. I wonder if you’d get the same flash if you converted to slow-mo after the fact rather than filming in slow-mo.
No, but for splashing liquid just interpolating frames rarely looks right compared to actual high frame rate. I mean imagine interpolating one of those milk drop videos or whatever, it would never quite look right. I’ve done of for some things (Hands moving slowly already worked well)
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