Operating Manual CCD Camera Models ST-7E, ST-8E and ST-9E Santa Barbara Instrument Group 1482 East Valley Road • Suite 33 PO Box 50437 Santa Barbara, CA 93150 Phone (805) 969-1851 • Fax (805) 969-4069 Web: • Email:
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. This equipment generates, uses, and can radiate radio frequency energy and if not installed and used in accordance with the instructions, may cause harmful interference to radio communications.
Table of Contents 1. 1.1. 1.2. Introduction .................................................................................................................1 Road Map of the Documentation ...............................................................................1 Quick Tour....................................................................................................................1 1.2.1. CCDOPS Software ....................................................................................2 1.2.
.5. Modular Family of CCD Cameras............................................................................26 4.6 Connecting the older model CFW-6 filter wheel to the Camera ..................................30 4.7 Battery Operation .............................................................................................................31 5. 5.1. 5.2. 5.3. 5.4. 5.5. 5.6. 5.7. 5.8. Advanced Imaging Techniques ..............................................................................
Section 1 - Introduction 1. Introduction Congratulations and thank you for buying one of Santa Barbara Instrument Group's CCD cameras. The model ST-7E, ST-8E and ST-9E are SBIG's fourth generation CCD cameras and represent the state of the art in CCD camera systems with their low noise and advanced capabilities, including Kodak's new Blue Enhanced E series of CCDs.
Section 1 - Introduction 1.2.1. CCDOPS Software Follow the instructions below to run the CCDOPS software and display and process sample images included on the distribution diskette. • Install the software onto your hard disk. For Windows this involves running the Setup.exe file on the first diskette. For Macintosh or DOS this involves copying the contents of the floppy disk to a folder or directory on your hard disk.
Section 1 - Introduction • Load up the other sample images and display them using the photo display mode. • If you find that the display is too dark or bright, try setting Auto Contrast in the display menu or adjust the background and range parameters to achieve the best display. Usually your monitor brightness and contrast want to be set fairly high. Note: Full daylight at F/22 will saturate these cameras with the shortest exposure. With a camera lens start out in dim room light.
Section 2 - Introduction to CCD Cameras 2. Introduction to CCD Cameras This section introduces new users to CCD (Charge Coupled Device) cameras and their capabilities and to the field of CCD Astronomy and Electronic Imaging. 2.1. Cameras in General The CCD is very good at the most difficult astronomical imaging problem: imaging small, faint objects. For such scenes long film exposures are typically required.
Section 2 - Introduction to CCD Cameras horizontal register of pixels. This register collects a line at a time and then transports the charge packets in a serial manner to an on-chip amplifier. The final operating step, charge detection, is when individual charge packets are converted to an output voltage. The voltage for each pixel can be amplified offchip and digitally encoded and stored in a computer to be reconstructed and displayed on a television monitor.
Section 2 - Introduction to CCD Cameras TE Cooler Microcontroller Clock Drivers 16 Bit A/D Preamp PC Interface Telescope Interface Desktop Power Supply Tracking CCD Shutter Imaging CCD Host Computer Parallel Interface Figure 2.2 - CCD System Block Diagram As you can see from Figure 2.2, the ST-7E, ST-8E and ST-9E are completely self contained. Unlike our previous products, the ST-7E, ST-8E and ST-9E contain all the electronics in the optical head.
Section 2 - Introduction to CCD Cameras using passive radiators and a small fan, making the design and operation of the heads simple and not inconvenienced by requirements for liquid recirculation cooling. The ST-9E includes SBIG's secondary TE/Liquid cooling booster. Since the CCD is cooled below 0°C, some provision must be made to prevent frost from forming on the CCD. The ST-7E, ST-8E and ST-9E cameras have the CCD/TE Cooler mounted in a windowed hermetic chamber sealed with an O-Ring.
Section 2 - Introduction to CCD Cameras have a single stage TE cooler and a temperature sensing thermistor on the CCD mount to monitor the temperature. The ST-9E has a supplemental second stage cooling booster with water cooling as an option (described in section 6.1). The microcontroller controls the temperature at a user-determined value for long periods. As a result, exposures hours long are possible, and saturation of the CCD by the sky background typically limits the exposure time.
Section 2 - Introduction to CCD Cameras minute, eliminating the many "hot" pixels one often sees across the image, which are simply pixels with higher dark current than average. 2.4.4. Flat Field Images Another way to compensate for certain unwanted optical effects is to take a "flat field image" and use it to correct for variations in pixel response uniformity across the area of your darksubtracted image.
Section 2 - Introduction to CCD Cameras (High = 9µ2 pixels, Medium = 18µ2 pixels, Low = 27µ2 pixels). When binning is selected the electronic charge from groups of 2 by 2 or 3x3 pixels is electronically summed in the CCD before readout.. This process adds no noise. Binning should be used if you find that your stellar images have a halfwidth of more than 3 pixels. If you do not bin, you are wasting sensitivity without benefit. The halfwidth of a stellar image can be determined using the crosshairs mode.
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.
Section 2 - Introduction to CCD Cameras purpose is simply to make a record or catalog the image file for easy identification, a dot matrix or laser printer should be fine. Inkjet printers are getting very good, though. 2.6. Black and White vs. Color The first and most obvious appearance of a CCD image is that it is produced in shades of gray, rather than color.
Section 3 - At the Telescope with a CCD Camera 3. At the Telescope with a CCD Camera This section describes what goes on the first time you take your CCD camera out to the telescope. You should read this section throughout before working at the telescope. It will help familiarize you with the overall procedure that is followed without drowning you in the details. It is recommended you first try operating the camera in comfortable, well lit surroundings to learn its operation. 3.1.
Section 3 - At the Telescope with a CCD Camera RA DEC * Figure 3.1 Orientation of the Optical Head Viewed from Back. (Pixel 1,1 is at the upper left in this view) 3.3. Establishing a Communications Link When the CCDOPS program is initiated it will automatically attempt to establish a link to the camera. This involves identifying the type of CCD head. If the software is successful the "Link" field in the Status Window is updated to show the type of camera found.
Section 3 - At the Telescope with a CCD Camera This preliminary step will save you much time in initially finding focus. The approximate distance behind the eyepiece tube for each of our CCD cameras is listed in Table 3.1 below: Camera ST-5C ST-237/STV ST-6 ST-7E/8E/9E Distance 0.660 inch 0.680 inch 0.560 inch 0.920 inch Diffuser Table 3.1 - Camera Back Focus Back Focus Distance from Table 3.
Section 3 - At the Telescope with a CCD Camera the eyepiece barrel. The next time the CCD is used the eyepiece should be first inserted into the tube to the scribe mark, and the telescope visually focused and centered on the object. At f/6 the depth of focus is only 0.005 inch, so focus is critical. An adapter may be necessary to allow the eyepiece to be held at the proper focus position. SBIG sells extenders for this purpose. 3.5.
Section 3 - At the Telescope with a CCD Camera using the Dark Subtract command. By subtracting the dark frame, pixels which have higher dark current than the average, i.e., "hot" pixels, are greatly suppressed and the displayed image appears much smoother. Visibility of faint detail is greatly improved. The CCDOPS program also supports the use of flat field frames to correct for vignetting and pixel to pixel variations, as well as a host of other image processing commands in the Utility menu.
Section 3 - At the Telescope with a CCD Camera Another aspect of the Focus command and its various modes is the Camera Resolution3 setting in the Camera Setup command. Briefly, the Resolution setting allows trading off image resolution (pixel size) and image capture time while field of view is preserved. High resolution with smaller pixels takes longer to digitize and download than Low resolution with larger pixels. The cameras support High, Medium, Low and Auto resolution modes.
Section 3 - At the Telescope with a CCD Camera One of the reasons that SBIG autoguiders are often better than human guiders is that, rather than just stabbing the hand controller to bump the guide star back to the reticule, it gives a precise correction that is the duration necessary to move the guide star right back to its intended position. It knows how much correction is necessary for a given guiding error through the Calibrate Track command.
Section 3 - At the Telescope with a CCD Camera Color imaging places some interesting requirements on the user that bear mentioning. First, many color filters have strong leaks in the infrared (IR) region of the spectrum, a region where CCDs have relatively 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 - Camera Hardware 4. Camera Hardware This section describes the modular components that make up the CCD Camera System and how they fit into the observatory, with all their connections to power and other equipment. 4.1. System Components The ST-7E, ST-8E and ST-9E CCD cameras consist of four major components: the CCD Sensors and Preamplifier, the Readout/Clocking Electronics, the Microcontroller, and the power supply.
Section 4 - Camera Hardware required is that with most modern telescope mounts the drift over the relatively short 1 minute interval is small enough to preserve round star images, a feat that even the best telescope mounts will not maintain over the longer ten minute interval.
Section 4 - Camera Hardware the relay is inactivated there is a connection between the Common and the Normally Closed contact. When the relay is activated (trying to correct the telescope) the contact is between the Common and the Normally Open contacts. If your hand controller is from a relatively recent model telescope it probably has four buttons that have a "push to make" configuration. By "push to make" we mean that the switches have two contacts that are shorted together when the button is pressed.
Section 4 - Camera Hardware A + relay wiper - relay c A B nc C c B potentiometer nc no no C B: Modified Joystick A: Unmodified Joystick Figure 4.3 - Joystick Modification A slight variation on the joystick modification is to build a complete joystick eliminator as shown in Figure 4.4 below. The only difference between this and the previous modification is that two fixed resistors per axis are used to simulate the potentiometer at its mid position.
Section 4 - Camera Hardware Camera A/D Resolution ST-5C ST-237 STV ST-6 ST-7E/8E/9E 16 bits 12 bits 10+2 bits 16 bits 16 bits Temperature Regulation Electromechanical Shutter/Shutter Wheel/Vane Closed Loop Shutter Wheel Closed Loop Shutter Wheel Closed Loop Shutter Wheel Closed Loop Vane Closed Loop Shutter Table 4.2 - System Features Electronic Shutter 0.01 second 0.01 second 0.001 second 0.
Section 4 - Camera Hardware CCD Used Number of Pixel Array Camera Pixels Dims. Dimension Tracking TC-211 192 x 164 13.75 x 16µ 2.6 x 2.6mm CCD ST-5C TC-255 320 x 240 10 x 10µ 3.2 x 2.4mm ST-237 TC-237 640 x 480 7.4 x 7.4µ 4.7 x 3.6mm STV TC-237 320 x 200 14.8 x 14.8 4.7 x 3.0mm ST-6 TC-241 375 x 242 23 x 27µ 8.8 x 6.6mm ST-7E KAF0401E 765 x 510 9 x 9µ 6.9 x 4.6mm ST-8E KAF1602E 1530 x 1020 9 x 9µ 13.8 x 9.2mm ST-9E KAF0261E 512 x 512 20 x 20µ 10.2 x 10.2mm Table 4.
Section 4 - Camera Hardware length is the focal length of the telescope or lens. Also remember that 1° = 3600 arcseconds. Read Noise - The readout noise of a CCD camera affects the graininess of short exposure images. For example, a CCD camera with a readout noise of 30 electrons will give images of objects producing 100 photoelectrons (very dim!) with a Signal to Noise (S/N) of approximately 3 whereas a perfect camera with no readout noise would give a Signal to Noise of 10.
Section 4 - Camera Hardware C8, 8" f/10 LX200, 10" f/35 Pixel Field of Pixel Field of Size View Size View (arcsecs) (arcsecs) (arcmins) Camera (arcmins) Tracking 4.2x4.2 1.3x1.5 11.7x11.7 3.7x4.3 CCD ST-5C 5.4x4.1 1.0x1.0 14.4x10.8 2.7x2.7 ST-237 8.0x6.0 0.75x0.75 21.6x16.2 2.0x2.0 STV 8.0x5.0 1.5x1.5 21.6x13.5 4.0x4.0 ST-6 14.6x11.1 2.3x2.7 38.9x29.5 6.2x7.3 ST-7E 11.9x7.9 0.9x0.9 31.2x20.8 2.4x2.4 ST-8E 23.8x15.8 0.9x0.9 62.4x41.6 2.4x2.4 ST-9E 17.6x17.6 2.0x2.0 46.2x46.2 5.3x5.3 Table 4.
Section 4 - Camera Hardware wires connects to the CFW-6. The black wire of the three-wire group mates to the brown or black wire of the CFW-6. 4.7 Battery Operation The ST-7E/8E/9E can be operated off of a 12 volt car or marine battery using a the optional 12V power supply or using a power inverter. We have used the Radio Shack model 22-132A, 12 volt DC to 115 volt AC Portable Power Inverter (140 watt) with good success. The camera draws 2..
Section 5 - Advanced Imaging Techniques 5. Advanced Imaging Techniques With practice, you will certainly develop methods of your own to get the most from your CCD camera. In this section we offer some suggestions to save you time getting started in each of the different areas outlined below, but these suggestions are by no means exhaustive. 5.1.
Section 5 - Advanced Imaging Techniques 5.4. Taking a Good Flat Field If you find that flat field corrections are necessary due to vignetting effects, CCD sensitivity variations, or for more accurate measurements of star magnitudes, try either taking an image of the twilight sky near the horizon or take an image of a blank wall or neutral grey card. The Kodak CCDs may have a low contrast grid pattern visible in the sky background. A flat field will eliminate this.
Section 5 - Advanced Imaging Techniques functions except when you are in Full Frame Focus Mode. It will then automatically switch to Low Resolution Mode. If you further select Planet Mode for focusing, the camera will switch back to High Resolution on the selected box area. The small pixel size, is best for critical focusing. Planet mode will result in fast digitization and download times since only a small portion of the frame is read out.
Section 5 - Advanced Imaging Techniques what alignment operations were done to the individual components of IMAGE to achieve the end result. In the following discussions this track list file will be referred to as TRACK. 5. Repeat steps 3 and 4 as many times as desired for all the objects you wish to image, each time choosing a set of corresponding new names for the IMAGE and TRACK files. 6. You will now create a combined flat field image for each Track and Accumulate image you captured.
Section 5 - Advanced Imaging Techniques mechanical problems, though. You still need a good polar alignment and a rigid mount between the guide scope and the main scope or you need to use an off-axis guider, with all its inherent difficulties. A good declination drive, free of backlash, is desirable although not absolutely necessary. Finally, modern drive correctors with periodic error correction (PEC) or permanent periodic error correction (PPEC) will ease the difficulty of achieving good results.
Section 6 - Accessories for your CCD Camera 6. Accessories for your CCD Camera This section briefly describes the different accessories available for your CCD camera. 6.1. Cooling Booster The cooling booster, which is included with the ST-9E and is an option for the ST-7E and ST-8E, is a small module that gets installed inside the back compartment of the camera. This section tells you how to best use the Cooling Booster. SBIG understands that water-cooling is a major annoyance.
Section 6 - Accessories for your CCD Camera ambient temperature if ambient temperature water is used. If colder water is used, the head may fog or frost up, depending on the dew point. . The exposed electronics inside the ST-7/8 will get wet, and corrode. The hoses will start dripping condensation, and you will have a mess. Keep the ice for a cold drink! At the end of the evening, stop the pump, and raise the outlet hose above the camera to let all the water drain out of the system.
Section 6 - Accessories for your CCD Camera 6.6. SGS - Self-Guided Spectrograph The SGS Self Guided Spectrograph takes the tedium out of spectroscopy by allowing you to image and guide the source on the tracking CCD while acquiring its spectra on the imaging CCD. No more hunting around to place the object on the slit! With the SGS you can measure galactic redshifts, stellar classifications and determine nebular constituency.
Section 6 - Accessories for your CCD Camera 6.8. SBIG Technical Support If you have any unanswered questions about the operation of your CCD camera system or have suggestions on how to improve it please don't fail to contact us. We appreciate all your comments and suggestions.
Section 7 - Common Problems 7. Common Problems This section discusses some of the more common problems others have encountered while using our CCD cameras. You should check here if you experience difficulties, and if your problem still persists please contact us to see if we can work it out together. Achieving Good Focus - Achieving a good focus is one of the most difficult areas in working with CCD cameras due to the lack of real time feedback when focusing.
Section 7 - Common Problems following suggestions. The easiest method of finding objects is to use a reticule eyepiece, if the object is bright enough to see. Pull the CCD optical head from the eyepiece holder and insert a 12-20mm eyepiece, focussing the eyepiece by sliding it in and out of the eyepiece holder, not by adjusting the telescope's focus mechanism. Center the object carefully (to within 10% of the total field) and then replace the CCD optical head.
Section 7 - Common Problems cause A/D Timeout and other parallel errors. Refer to you computer manual for how to use the BIOS Setup utility to configure your parallel port.
Section 8 - Glossary 8. 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. Kodak CCDs with the antiblooming option 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.
Section 8 - Glossary Flat Field - A Flat Field is a image with a uniform distribution of light entering the telescope. An image taken this way is called a flat field image and is used with CCDOPS to correct images for vignetting. Focal Reducer - A Focal Reducer reduces the effective focal length of an optical system. It consists of a lens mounted in a cell and is usually placed in front of an eyepiece or camera.
Section 8 - Glossary can be changed. Subsequent downloads will be of the area inside the box resulting in a much faster update rate. Quantum Efficiency - Quantum Efficiency refers to the fractional number of electrons formed in the CCD pixel for a given number of photons. Quantum Efficiency is usually plotted as a function of wavelength. Readout Noise - Readout noise is associated with errors generated by the actual interrogation and readout of each of the CCD pixels at the end of an exposure.
Section 8 - Glossary High levels of sky background can increase the noise in images just like dark current. For some objects deep sky filters can be used to reduce the sky background level. Seeing - Seeing refers to the steadiness and the clarity of the atmosphere during an observing session. TE Cooler - The TE Cooler is a Thermal Electric cooling device used to cool the CCD down to operating temperature. The CCD is mounted to the TE Cooler which is mounted to a heat sink, usually the camera head housing.
Appendix A - Connector Pinouts A. Appendix A - Connector ad Cables This appendix describes the various connectors and cables used with the ST-7E/8E/9E. A.1. Appendix A - Connector Pinouts Tables A1 and A2 below show the pin-outs of the Telescope and Power connectors on the ST7E/8E/9E.
Appendix A - Connector Pinouts Telescope port with our TIC-78 (Tracking Interface Cable), or you can make your own cable. Figure A1 below shows the pinouts on these telescopes.
Appendix B - File Formats B. Appendix C - Maintenance This appendix describes the maintenance items you should know about with your CCD camera system. B.1. Cleaning the CCD and the Window The design of SBIG cameras allows for cleaning of the CCD. The optical heads are not evacuated and are quite easy to open and clean. When opening the CCD chamber, one should be very careful not to damage the structures contained inside.
Appendix C - Capturing a Good Flat Field C. Appendix C - Capturing a Good Flat Field This appendix describes how to take a good flat field. A good flat field is essential for displaying features little brighter than the sky background. The flat field corrects for pixel non-uniformity, vignetting, dust spots (affectionately called dust doughnuts), and stray light variations. If the flat field is not good it usually shows up as a variation in sky brightness from on side of the frame to the other. C.1.
Index Establish COM Link, 16 PC Setup, 16 communications link, 16 connector Telescope, 49 connector (CPU) RELAYS, 23, 37 cooling, 8, 48 co-register images, 20, 23 crop, 18 crosshairs, 18 dark current, 8 dark frame, 8, 9, 15, 18 Dark Frame (def), 45 Dark Noise (def), 45 Dark Subtract Command, 19 dark subtracted, 9, 15, 18 DCS, 9, 45 Declination, 15, 23, 37, 44 desiccant, 51 Diffuse Magnitude, 19 diffuser, 16 Dim mode, 19 displaying images, 18 double correlated sampling, 9 Double Correlated Sampling (def), 45
Index negative image, 18 nosepiece, 15 observatory, 23 optical head, 15, 23 optical head orientation, 16 O-ring, 8 path (def), 46 path/filter (def), 46 PC, 8 PC Setup Command, 16 PEC drive correctors, 20, 37 photometric measurements, 46 Photometry (def), 46 pixel nonuniformity, 19 pixel size, 10, 28 Pixel Size (def), 46 pixel uniformity, 10 planet mode, 19 Planet mode (def), 46 planets, 5, 16, 30, 33 POWER connector, 15 power supply, 8, 15 power supplyr, 23 PPEC drive correctors, 20, 37 preamp, 8, 23 printi
Index zoom, 18 separations, 19 setup, 15 SGS-Self Guided Spectrograph, 41 sharpen, 19 shutter, 8 signal to noise ratio, 22, 29 sky background, 5, 20 smoothing, 19 snapshot, 23 software, 26, 41 spectral range, 5 spectrograph, 41 Status Window, 16 Link field, 16 stellar magnitude, 19 stellar temperature, 19 super pixel, 19 taking images, 18 TE cooler, 8 TE Cooler, 7 TE Cooler (def), 48 Technical Support, 42 telescope, 10, 15, 18, 20 Telescope connector, 49 telescope hand controller, 18, 20, 23, 24 temperatur