Operating Manual for the Model ST-5C Advanced CCD Camera Santa Barbara Instrument Group
Santa Barbara Instrument Group 1482 East Valley Road • Suite 33 PO Box 50437 Santa Barbara, CA 93150 PHN (805) 969-1851 (FAX) (805) 969-4069 Email: sbig@sbig.com Home page: www.sbig.com Note: This equipment has been tested and found to comply with the limits for a Class B digital device pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation.
Table of Contents 1. Introduction to CCD Cameras....................................................................................................3 1.1. How CCDs Work.......................................................................................................................3 1.2. CCDs Applied to Astronomical Imaging..................................................................................4 1.2.1. Cooling....................................................................................
B. Appendix B - Maintenance ...................................................................................................... 35 B.1. Replacing the Fuse .................................................................................................................. 35 B.2. Disassembling/Reassembling the Optical Head.................................................................... 35 B.3. Cleaning the Optical Windows...................................................................................
Introduction Congratulations and thank you for buying the SBIG ST-5C Advanced CCD Camera. This camera offers incredible performance in a small package for a moderate cost. Using the camera will expand your astronomical experience by allowing you to easily take images like the ones you've seen in books and magazines, but never seen when peeking through the eyepiece.
Introduction useful hints and tips for using the camera. Again, this is a good section to read once you have had a little time with the camera. • Finally, the Appendices provide a wealth of technical information about the camera.
Section 1 - Introduction to CCD Cameras 1. Introduction to CCD Cameras The CCD (charge coupled device) is very good at the most difficult astronomical imaging problem: imaging small, faint objects. For such scenes, long film exposures are typically required.
Section 1 - Introduction to CCD Cameras encoded and stored in a computer to be reconstructed and displayed on a television monitor."2 Output Readout Register Y=1 Amplifier Y=N X=1 X=M Figure 1.1 - CCD Structure 1.2. CCDs Applied to Astronomical Imaging When CCDs are applied to astronomy, with the relatively long exposure times (compared to the 30 frames per second used in video camera), special considerations need to be applied to the system design to achieve the best performance.
Section 1 - Introduction to CCD Cameras the temperature at a user determined value for long periods. As a result, exposures up to an hour long are possible, and saturation of the CCD by the sky background typically limits the exposure time. The sky background conditions also increase the noise in images, and in fact, as far as the CCD is concerned, there is no difference between the noise caused by dark current and that from sky background.
Section 1 - Introduction to CCD Cameras The typical CCD astronomer is taking images of faint galaxies and nebulae. While exposures are long, you very rarely will expose the CCD to more than a small fraction of its full well capacity on these dim objects. Some stars in the image will expose to the full well capacity, but not much of the nebulosity. So even though small pixel size CCDs have lower full well capacities than large pixel CCDs, most applications do not stress this CCD parameter. 1.3.3.
Section 1 - Introduction to CCD Cameras whereby data from the image area, after completing the exposure, is rapidly shifted into the storage area where it is then digitized. A fast shift from the imaging area to the storage area insures minimal streaking. Once the image is in the storage area, it can read out by the camera electronics without causing streaking.
Section 1 - Introduction to CCD Cameras CCD has a full well capacity of 50,000 electrons and a read noise of 30 electrons RMS giving a dynamic range of roughly 1700. A 12 bit A/D offers a dynamic range of 4096 and would cover that CCD fairly well. One thing you do want to do with the A/D is make sure that the A/D's noise (typically 1 count) is lower than the CCD's noise so that you are truly CCD limited.
Section 1 - Introduction to CCD Cameras The TC255 CCD used in your camera is made using Texas Instrument's Virtual Phase technology that gives excellent Blue response compared to other CCDs. This is achieved by reducing the number of photon-absorbing clocking gates in the CCD. Figure 1.2 - CCD Quantum Efficiency 1.4. Camera Hardware Architecture This section describes the ST-5C Advanced CCD Camera from a systems standpoint.
Section 1 - Introduction to CCD Cameras The ST-5C camera is a two piece system consisting of an Optical Head and a CPU. The Optical Head houses the CCD and Preamplifier and the CPU contains the Readout and Control Electronics. The CPU is powered by an external 12 VDC source. For users in the US and in Japan, wall tranformers rated at 12 VDC / 2 Amps are supplied, for users outside these areas a Cigarette Lighter Adapter is provided.
Section 2 - The First Day with the Camera 2. The First Day with the Camera This section takes you step-by-step through your first use of the software and camera. 2.1. Setting up the System This section tells you how to install the CCDOPS software and establish a communications link with the camera. 2.1.1 Installing the CCDOPS Software The CCDOPS software is provided on floppy diskette, and should be copied to your system's hard disk prior to use.
Section 2 - The First Day with the Camera 2.1.2. Getting Acquainted with CCDOPS Software Upon entering CCDOPS a warning (referred to as an Alert) states no camera is hooked up yet.
Section 2 - The First Day with the Camera box to the DEMO.SLD script which we created for you and hit Enter. Now you are presented with more choices. Temporarily ignore these and hit Enter again. When in doubt, just hit Enter to use the standard defaults. You are now viewing a library of images created with the TC-255 chip in your camera. These will run until you hit Esc. You can adjust your monitor's brightness or contrast for best view. If you find an image you wish to freeze, hit the Space bar.
Section 2 - The First Day with the Camera Lunar/Planetary and Medium settings. Hit Enter. A sharpened image of Jupiter comes up and notice how the red spot (light oval) now shows on Jupiter's right side by one of its moons. Also, cloud band detail has been enhanced. At this point, you could save this image, but be cautious and make sure you have read the manual and understand what the save function can do to the original unsharpened Jupiter image.
Section 2 - The First Day with the Camera CPU. Connect the other end of the parallel cable into your computer's Parallel port (printer port). Finally plug the power supply into the CPU. At this point the camera should activate the small motor in the optical head to find the home position on the internal shutter wheel and the camera should be ready to use. Important Note: Never connect or disconnect the CCD head from the CPU box unless the power cord is unplugged from the CPU.
Section 2 - The First Day with the Camera brings up more advanced crosshair commands. Hit Esc twice to view just the image. This is what you will typically view after you capture an image. Next, Esc back to the main menu and hit the Grab command again. Select Dark frame:None. With the camera nosepiece uncovered, hit Enter to begin another exposure. This time you are taking a light frame. Notice how smooth the image looks. Repeat the above steps used in evaluating pixels in the dark frame.
Section 2 - The First Day with the Camera and may be incorrect. Refer to the CCDOPS manual and the Telescope Setup and Edit Parameters commands for more on this. This data will always be connected with the saved image as long as it is viewed by any CCDOPS software such as a friend's or a magazine's.5 Repeat the above procedures to capture, display and save images until you are confident enough to take the next step of coupling your CCD camera to a telescope at night.
Section 2 - The First Day with the Camera telescope chip DEC (Y) cord RA (X) Figure 2.3 - Camera Orientation If you haven't done so already, power up the CCD camera and computer. Under the Misc menu use the Telescope Setup command to enter your telescope information. For the Aperture item enter the clear aperture in square inches (for example an 8" SCT is 43 square inches).
Section 2 - The First Day with the Camera To position the planet frame with the mouse, click and drag the upper-left and lowerright corners of the box or click and drag the center. To position it with the keyboard (DOS only), you use the arrow keys in combination with the T key. The T key toggles whether you are moving the Center, the Upper-Left or the Lower-Right corner of the box. You can see which is currently selected in the upper-left corner of the display adjacent to the Hot label.
Section 2 - The First Day with the Camera below, “Advanced Imaging Techniques” will also give you some good insight into how to effectively use your camera.
Section 3 - Advanced Topics 3. Advanced Imaging Techniques The following sections describe some of the advanced uses of CCD cameras. While you may not use these features the first night, they are available and a brief description of them is in order for your future reference. 3.1.
Section 3 - Advanced Topics Color imaging places some interesting requirements on the user that bear mentioning. First, many color filters have strong light transmission in the infrared (IR) region of the spectrum, a region where CCDs have very good response. If the IR light is not filtered out, then combining the three images into a color image can give erroneous results. If your Blue filter has a strong IR leak (quite common), then your color images will look Blue.
Section 4 - Glossary 4. Glossary Antiblooming Gate - When a CCD pixel has reached its full well capacity, electrons can effectively spill over into an adjoining pixel. This is referred to as blooming. The Antiblooming gate can be used to help stop or at least reduce blooming when the brighter parts of the image saturate. Astrometry - Astrometry is the study of stellar positions with respect to a given coordinate system. Autoguider - All SBIG CCD cameras have auto guiding or "Star Tracker" functions.
Section 4 - Glossary Frame Transfer CCDs - Frame Transfer CCDs are CCDs that have a metal mask over some portion (usually half) of the pixel array. The unmasked portion is used to collect the image. After the exposure is complete, the CCD can very quickly shift the image from the unmasked portion of the CCD to the masked portion, thus protecting the image from light which may still be impinging on the CCD. This acts as an electronic shutter.
Section 4 - Glossary photoelectrons generated in the CCD for a 0th magnitude star per second per square inch of aperture. Saturation - Saturation refers to the full well capacity of a CCD pixel as well as the maximum counts available in the A/D converter. The pixel is saturated when the number of electrons accumulated in the pixel reaches its full well capacity. The A/D is saturated when the input voltage exceeds the maximum.
Section 5 - Hints and Tips 5. Hints and Tips This section contains hints and tips to get the most use out of your camera and software. There is a section of Question and Answers to the most common questions followed by several sections of tips. 5.1 Question and Answer This section contains answers to some of the more common questions we hear in the Technical Support department. Q. Is there a short cut to focusing the camera? A.
Section 5 - Hints and Tips Q. Can I write my own software for the camera? A. Appendix B describes the file format used to save images. You can also request an Application Note from the manufacturer telling how to interface and program to the camera. Q. Is there other software available for the camera? A. You can upgrade your camera with the Color Filter Wheel and CCDCOLOR software. Also there are several third party software packages for image processing, camera control and various printer output. Q.
Section 5 - Hints and Tips the field of view and shorten the exposure times. Do not underestimate the benefits of focal reducing your f/10 SCT systems! 5.2. CCDOPS Use Tips • If you display an image and nothing shows, check that the Auto Contrast was enabled. • When selecting a Track and Accumulate guide star, it is not necessary to exactly set the cursor on the center of the selected star. It automatically snaps to the brightest pixel, not necessarily the geometric visual center.
Section 5 - Hints and Tips • Images will always look better when displayed on a video monitor, however, an active matrix LCD display is pretty close except in brightness. • You may wish to change your display and hard drive sleep cycles (battery conservation) to longer "keep awake" times so as not to interfere with image acquisition (long Track and Accumulate). • LED flashlights help to see the keyboard when the display is dimmed red. 5.4.
Section 5 - Hints and Tips in the CCD camera view. The chip is only .1 x .13 inch in size and 90 degree diagonals are never rotationally collimated to optical axis close enough to use for CCD work. Special laser collimated diagonals are available for this purpose as well as CCD framing oculars with exact reticle patterns to match the CCD chip. • Digital setting circles with hi-res encoders (1/12 degree or better) can get you close to faint objects if you are polar aligned and they are "dialed in" as well.
Appendix A - Specifications A. Appendix A - Specifications This appendix lists the specifications for the SBIG ST-5C AdvancedCCD camera. CCD Active Area Field of View Pixels/Pixel Size Read Noise Dark Current Full Well Capacity Cooling A/D Converter Power Requirements Telescope Port Communications Port Electronic Shutter Mechanical Shutter Color Filter Wheel Weight of Optical Head (less cable) Size of Optical Head F# throughput of Filter Wheel A.1 Texas Instruments TC255 3.2 x 2.4 mm (.126" x .094") 5.
Appendix A - Specifications A.1 Telescope Port 123456 1 = +RA (Right) 2 = +DEC (Up) 3 = -DEC (Down) 4 = -RA (Left) 5 = Ground 6 = No Connect Figure A.3 - Telescope Port Note that the four outputs are active-low, open-drain outputs without internal pull-ups and are capable of sinking 250 mA DC to ground when activated. They have a breakdown voltage of 45V, a typical on resistance of 1.3Ω and an avalanche energy of 75 mJ for driving inductive loads.
Appendix B - Maintenance B. Appendix B - Maintenance This appendix describes the maintenance items you should know about with your CCD camera system. B.1. Replacing the Fuse The CPU is internally fused with a 2 amp fast blow fuse. The fuse is located inside the CPU box on the printed circuit board. Remove the four screws on the bottom of the CPU box to access the fuse holder. B.2.
Appendix B - Maintenance from upright a stream of cold liquid (the propellant) will issue forth rather than the burst of air. 2. In lieu of canned air, a small, soft, camel hair brush can be used to wipe dust from the windows. 3. Finally, for hard to remove particles or water spots, use a Q-Tip lightly dampened in Isopropyl Alcohol to clean the windows. Note: The key to cleaning optical surfaces is successive cleanings with a fresh Q-tip each time. B.4.
Index A/D converter .................................................... 7 antiblooming..................................................7, 23 Antiblooming Gate (def).......................................23 astrometric measurements .....................................23 Astrometry (def) ................................................23 Autoguider (def) ................................................23 autoguiding ......................................................22 backfocus........................
Index TC255 .......................................................... 1, 9 TE cooler......................................................4, 10 TE Cooler (def)..................................................25 telescope..........................................................19 telescope hand controller.................................. 19, 22 telescope port.................................................1, 22 thermistor ......................................................... 4 TIFF format (def) ....
