Re: Shutter Speed

[Jeff Lewin] "But if your shutter opens and closes 2000 times in a second, the camera is only going to record 30 of those frames right?"

Ok, time for me to chime in here, and you may have allready figured this out. If you set the shutter speed at 1/2000 on a video camera you the shutter doesn't open 2000 times a second. In fact, there is no shutter on a video camera, but there is a scan that happend on the CCD. When the shutter speed is set to 1/2000 second, the entire CCD gets scanned by the circuitry in 1/2000 of a second, then the information is processed and the frame is created sent to the video processors as a single frame of video (a frame has two fields). The scanning of the CCD is so fast that the sensitivity of the ccd to light is greatly reduced. The longer you can expose a CCD to light the more information it can give you so that's why you loose sensitivity as you increase the shutter speed of the video camera. If you want to record video at a higher than standard frame rate you need to do two things. Scan the image sensor faster and turn the signal into frames faster. Only scanning the sensor faster is easy and cheap. Sending frames to a recorder at a faster rate is very expensive and complicated. That's why only expensive video cameras and VTR's will do real high frame rate captures. I can't tell you the number of times that I've been asked how to turn video into great slow motion footage. Almost universally people will assume that if you set the shutter speed to a high value, like 1/2000 of a second, you'll get great slow-motion. That isn't the case. In many cases it looks worse than leaving the camera set to it's normal speed and letting software create your slow-motion from normal interlaced video. The only way to get real slow-mo from a video camera is to use a camera that has been specifically designed to record at higher than normal frame rates. There are no cheap cameras that do this. There is only one semi-pro camera that I’ve ever heard of that makes a stab at this by recording the standard 60 (59.94) fields per second as frames. I’ve never actually seen the footage from this camera, but I’ve been told it’s pretty good. The only pro-cameras that do this are the variable frame rate cameras that Sony, Thompson, and Panasonic make and they cost big bucks. It also takes big buck VTR’s to playback this special slow-mo tape. If software created interpolated slow-mo isn’t good enough for you, and you can’t afford about $80 K for a specialized camera, then use film cameras and over crank. Film cameras are still the only reasonable way to shoot at any frame rates over 120 FPS. We did a job a few years ago where we had to shoot at 500 FPS. While it is not impossible to build a video camera that will shoot at these speeds, it’s just not practical.