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From: henden@hpuxa.ircc.ohio-state.edu (Arne A. Henden)
Newsgroups: sci.electronics
Subject: Re: Does your CCD camera has shutters?
Summary: yes, speed isn't important to us
Keywords: CCD, Willmann-Bell
Message-ID: <1991Jan14.142242.6496@magnus.ircc.ohio-state.edu>
Date: 14 Jan 91 14:22:42 GMT
References: <1991Jan11.192038.27201@sunee.waterloo.edu>
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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