simpson@sunee.waterloo.edu (KFS Lam) (01/12/91)
Since I didn't get any answer from my last posting about electronic shutter, I guess I asked the wrong question. Ok, let me ask another question first. For people who used CCD cameras before, did your camera has a shutter? If it is, what kinds of shutter is it? How about telling me the type of sensor that is in the camera (such as interline, frame transfer, full frame, etc.)? What is the resolution? I hope I can get some feedback this time because I really need the info. For some of you who may have the luck to work with CCD sensors, I have a simple question. I am planning to use one of those full frame CCD area sensor for a camera. I forget the part number but it is from TI and it is a small resolution sensor (something like 190x200, something around there). If I clock the sensor in maximum allowable speed and use it without a shutter, will I get smear image due to the shifting of charge from top to bottom? I am hoping that the readout will be fast enough so the accumulation of charge will be small. Any help will be appreciated. Thanks in advance. simpson@sunee.waterloo.edu
henden@hpuxa.ircc.ohio-state.edu (Arne A. Henden) (01/14/91)
In article <1991Jan11.192038.27201@sunee.waterloo.edu> simpson@sunee.waterloo.edu (KFS Lam) writes: >Since I didn't get any answer from my last posting about >electronic shutter, I guess I asked the wrong question. >Ok, let me ask another question first. For >people who used CCD cameras before, did your camera has >a shutter? If it is, what kinds of shutter is it? How >about telling me the type of sensor that is in the >camera (such as interline, frame transfer, full frame, etc.)? >What is the resolution? I hope I can get some feedback this >time because I really need the info. > >Any help will be appreciated. Thanks in advance. > > simpson@sunee.waterloo.edu We use many CCDs here at OSU, all in full-frame mode with a mechanical shutter. We are more interested in using every sensitive pixel (since that is what you pay for) rather than speed. Others, such as Rich Stover at Lick, are using frame transfer devices so that, after an integration, the image can be quickly shifted to the shielded region and slowly read out while the next exposure is in progress. The TI TC210/211 device is the most common in the $1000 cameras you see advertised in Sky and Telescope. It is a 192x165 full frame device, which can be read out in about 1/2 second (50Kpixels/sec for optimum noise response). If you use it in full frame mode, this means that any exposure that gives significant signal in say 5 seconds will exhibit 10 percent smearing if you continue to expose while you are clocking the device. Frame transfer can move the 1/2 sensitive area into the shielded area in a millisecond or so, eliminating most smearing and also removing the need for a shutter (a dark slide can be used for getting bias frames). I suggest waiting for the book by Buil on CCD Astronomy (Willmann Bell, $24.95, 804-320-7016) for more info on using CCD systems. I proofed the book and it contains an awful lot of information. It should be out in the next couple of months. Hope this helps. Arne Henden