Polaroid ST-7E, ST-8E, ST-9E manual Electronic Imaging

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Section 2 - Introduction to CCD Cameras

readout noise less. It is handy when no connection to the telescope drive is possible. SBIG is proud to make self-guiding available to the amateur, making those long exposures required by the small pixel geometry of the ST-7 and ST-8 easy to achieve!

2.5.Electronic Imaging

Electronic images resemble photographic images in many ways. Photographic images are made up of many small particles or grains of photo sensitive compounds which change color or become a darker shade of gray when exposed to light. Electronic images are made up of many small pixels which are displayed on your computer screen to form an image. Each pixel is displayed as a shade of gray, or in some cases a color, corresponding to a number which is produced by the electronics and photo sensitive nature of the CCD camera. However, electronic images differ from photographic images in several important aspects. In their most basic form, electronic images are simply groups of numbers arranged in a computer file in a particular format. This makes electronic images particularly well suited for handling and manipulation in the same fashion as any other computer file.

An important aspect of electronic imaging is that the results are available immediately. Once the data from the camera is received by the computer, the resulting image may be displayed on the screen at once. While Polaroid cameras also produce immediate results, serious astrophotography ordinarily requires hypersensitized or cooled film, a good quality camera, and good darkroom work to produce satisfying results. The time lag between exposure of the film and production of the print is usually measured in days. With electronic imaging, the time between exposure of the chip and production of the image is usually measured in seconds.

Another very important aspect of electronic imaging is that the resulting data are uniquely suited to manipulation by a computer to bring out specific details of interest to the observer. In addition to the software provided with the camera, there are a number of commercial programs available which will process and enhance electronic images. Images may be made to look sharper, smoother, darker, lighter, etc. Brightness, contrast, size, and many other aspects of the image may be adjusted in real time while viewing the results on the computer screen. Two images may be inverted and electronically "blinked" to compare for differences, such as a new supernova, or a collection of images can be made into a large mosaic. Advanced techniques such as maximum entropy processing will bring out otherwise hidden detail.

Of course, once the image is stored on a computer disk, it may be transferred to another computer just like any other data file. You can copy it or send it via modem to a friend, upload it to your favorite bulletin board or online service, or store it away for processing and analysis at some later date.

We have found that an way to obtain a hard copy of your electronic image is to photograph it directly from the computer screen. You may also send your image on a floppy disk to a photo lab which has digital photo processing equipment for a professional print of your file. Make sure the lab can handle the file format you will send them. Printing the image on a printer connected to your computer is also possible depending on your software/printer configuration. There are a number of software programs available, which will print from your screen. However, we have found that without specialized and expensive equipment, printing images on a dot matrix or laser printer yields less than satisfactory detail. However, if the

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Contents Operating Manual Page Table of Contents Technique Road Map of the Documentation IntroductionQuick Tour Ccdops Software Ccdops for Windows or MacintoshCCD Camera Page Cameras in General Introduction to CCD CamerasHow CCD Detectors Work Full Frame and Frame Transfer CCDs Camera Hardware ArchitectureCCD System Block Diagram CCD Special Requirements CoolingDouble Correlated Sampling Readout Dark FramesFlat Field Images Pixels vs. Film GrainsGuiding Electronic Imaging Black and White vs. Color Page Step by Step with a CCD Camera At the Telescope with a CCD CameraAttaching the Camera to the Telescope Focusing the CCD Camera Establishing a Communications LinkCamera Back Focus Finding and Centering the Object Taking an ImageDisplaying the Image Processing the ImageAdvanced Capabilities Crosshairs Mode Photometry and AstrometrySub-Frame Readout in Focus Track and Accumulate Autoguiding and Self GuidingAuto Grab Color ImagingAt the Telescope with a CCD Camera Connecting the Power Connecting to the ComputerConnecting the Relay Port to the Telescope Camera HardwareUsing Mechanical Relays Push to Make Switch Modification Modular Family of CCD Cameras Joystick ModificationSystem Features 20.6x sizeum Focal length cm Camera Hardware Connecting the older model CFW-6 filter wheel to the Camera Battery Operation Page Advanced Imaging Techniques Lunar and Planetary ImagingDeep Sky Imaging Terrestrial ImagingTaking a Good Flat Field Changing the Camera ResolutionBuilding a Library of Dark Frames Flat Fielding Track and Accumulate Images Tracking Functions Advanced Imaging Techniques Page Accessories for your CCD Camera Cooling BoosterTri-color Imaging Camera Lens Adapters and Eyepiece ProjectionFocal Reducers AO-7 and Lucy-Richardson SoftwareThird Party Products and Services SGS Self-Guided SpectrographWindows Software Image Processing SoftwareSbig Technical Support Common Problems Common Problems Common Problems Page Glossary STV Glossary Glossary Appendix a Connector Pinouts Appendix a Connector ad CablesSbig Tracking Interface Cable TIC-78 Figure A1 CCD Connector for TIC Mating Cleaning the CCD and the Window Appendix C MaintenanceRegenerating the Desiccant Page Appendix C Capturing a Good Flat Field TechniquePage Index IBM PC Separations