A thousand FPS of goodness |
I'm pretty sure (though not certain) that the camera uses a Photobit PB-MV13 as its image sensor (the same sensor is found in cameras such as the Weisscam HS-1) and was made by AOS. The camera is identical to the AOS VITCam, and in fact, Redlake Imaging Studio is a rebranded version of AOS Imaging Studio.
Fortunately, it turns out that Apple was obsessed with Firewire until recent years, so the first generation (2006) Macbooks have full-sized Firewire ports, complete with 12V power. Plus, they were x86 (Core/Core 2 Duo), so they run Windows XP quite nicely.
The trickiest part of using this camera is lighting. At 500FPS, the camera is constrained to shutter speeds of 1/500 or faster. Furthermore, the 2005-era CMOS sensor it uses doesn't have the greatest sensitivity, and there is no option to turn up the sensor gain.
Initial tests with room lighting proved to be a dismal failure. I switched to a 300W halogen bulb, which at least gave usable results:
Sadly, the sensor really wants high color-temperature (bluer) lighting, so there was no way to make the image look decent with a halogen.
Fortunately, the home hydroponics market has spawned a bunch of semi-legit electronic metal halide ballasts. These are functionally equivalent to what the film industry calls "HMI" lights, and are good for around 25000 lumens at a color temperature of 5000K.
Lenses! |
Because the camera uses a sensor with a diagonal of 20mm, and not a full-frame 35mm sensor, the crop factor is approximately 2. This means that a 50mm normal lens behaves like a 100mm telephoto, and a 24mm wide-angle behaves like a normal lens.
Putting the metal halide lighting, a 50mm f/1.8 Nikkor lens, and some Jello together gave the following video:
If you look closely at the video, you'll notice numerous color and motion artifacts. These are not actual camera artifacts, but rather a consequence of the shitty early-90's AVI codec Imaging Studio uses. The solution was to export the frames as uncompressed BMP's first, then use FFMPEG to convert the sequence of BMP's into a high-quality video.
At this point, I also discovered that by default, Imaging Studio does not apply gamma correction, leading to some washed-out looking images. Applying a gamma of 1.5 and turning up the contrast resulted in much prettier, contrastier videos:
This past weekend, we (oneTesla) was at MuseCon in Chicago. One of the featured shows was Masters of Lightning (Terry Blake and Jeff Larson, with a pair of 12KW DRSSTC's). The sparks from the big coils were just bright enough to show up decently on the camera.
500FPS:
1000FPS (quick 'n dirty export with pretty bad artifacting):
Jeff also brought his wire exploder, so we filmed that as well. Both videos at 1000FPS.
The exploding wire produces some interesting stills:
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