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Digital Video Capture and High Frame Rates?
Jeff asks: "So the folks at a place called Conniption Films (great name) developed a camera called the Millisecond Camera which can shoot 12,000 frames of film a second. I read the article and thought 'Hmm that's neat' but then realized they were still using an analog process for shooting this highspeed film. Being a geek, not necessarily into the film side of things but curious nonetheless, I wonder, shouldn't a computer be able to do a better job of such a thing? They say the film runs around a spindle going 500 mph (!). Wouldn't that be prone to failure and use alot of energy? Wouldn't it be more appropriate, easier, and overall cheaper to just hook up a high res CCD to a beowulf </duck> cluster of 2 ghz+ machines and capture high speed images that way? Why hasn't it been done yet? Or has it and I haven't seen it yet?" I did a double-take, when I first read this question, and then got curious and did a little digging. Turns out, high frame rates are not exclusive to the analog photography world, and to illustrate my point, I provide this link. It's woefully short on details, and the explanations as to why a camera that can record 1M frames per second is limited to a playback of only 103 frames, but the technology is out there. Has anyone seen any other digital cameras out there with high frame-rates? What visual mischief could you aspiring photographers get into with such a camera?
A quick calculation on the bandwidth of capturing 12000 SVGA-resolution full color frames per second:
1024 (width) * 768 (height) * 4 (32-bit color) * 12000 (fps) = 377,487,360,00 bytes/second (35 Gbytes/s)
So no wonder they use film...
You can get around any bandwidth issues with a sufficiently large amount of cabling. The whole idea of doing this in parellel implies that. Anyway, compare the bandwidth of digital photography with the physical bandwidth of looping film through an eyepiece at 12,000 frames per second and you come up with a very different problem -- you've got to use TINY film, with an effective resolution much lower than what some of you linux numbercrunchers are assuming. "SVGA resolutions?" Think more like 320x240 -- and don't expect more than a few seconds per cannister, high costs, etc.
.000083 s. With low light, you need extremely sensitive equipment to even detect it and even more sensitive equipment to detect the subtle variations in wavelength that make up colors. Today's CCD cameras are very slow to register intensity light -- much slower than film. The chemical reaction in film triggered by exposure can be controlled much better, simply by changing the tolerance of the film -- which is why your high end, high speed shutter digital cameras are so godawful expensive. The $2500 Canon I've been looking at has roughly the same shutter speed as an equivalent $300 film camera. The extra price is NOT a "coolness" tax...it's for the set of three extremely high res CCD sensors and the chips capable of processing their information at that speed. My film prof used to say "digital ain't digital"...there's a quality factor of all digital electronics that can be poiled down to the quality of interpolation, quality of the ADC and of transistors leading up to it.
No, the problem is light itself. You don't get much of it captured with a shutter speed of
CCD kind of sucks, man. For all its glorious promise, the best CCD chipsets aren't all that much better than the wonderful X-10 spycam.
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