User manual SBIG STL-1001E

[. . . ] ASTRONOMICAL INSTRUMENTS SBIG Operating Manual Research Camera Models: STL-1001E, STL-1301E, STL-4020M, STL-6303E and STL-11000M Santa Barbara Instrument Group 147A Castilian Drive Santa Barbara, CA 93117 Phone (805) 571-7244 · Fax (805) 571-1147 Web:<www. sbig. com> · Email:<sbig@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. 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. However, there is no guarantee that interference will not occur in a particular installation. [. . . ] Of course, there are color video cameras, and a number of novel techniques have been developed to make the CCD chip "see" color. The most common way implemented on commercial cameras is to partition the pixels into groups of three, one pixel in each triplet "seeing" only red, green or blue light. The overall image will suffer a reduction in resolution on account of the process. A newer and more complicated approach in video cameras has been to place three CCD chips in the camera and split the incoming light into three beams. The images from each of the three chips, in red, green and blue light is combined to form a color image. For normal video modes, where there is usually plenty of light and individual exposures are measured in small fractions of a second, these techniques work quite well. However, for astronomical work, exposures are usually measured in seconds or minutes. The most efficient way of imaging under these conditions is to utilize all of the pixels, collecting as many photons of any wavelength, as much of the time as possible. In order to produce the best color images in astronomy, the most common technique is to take three images of the same object using a special set of filters and then recombine the Page 33 Section 2 - Introduction to CCD Cameras images electronically to produce a color composite or RGB color image. The Research model cameras contain internal motorized color filter wheel. When filters are installed in the filter wheel, light entering the camera passes through the colored filter before it strikes the CCD. The wheel is commanded to insert the green filter in place, and another image taken. When all three images have been saved, they may be merged into a single color image using SBIG or third party color software. Page 34 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. Step by Step with a CCD Camera In the following sections we will go through the steps of setting up and using your CCD camera. The next step is powering up the camera and establishing a communication link to your computer. Then you will want to focus the system, find an object and take an image. Once you have your light image with a dark frame subtracted, you can display the image and process the results to your liking. Each of these steps is discussed in more detail below. 3. 2. Attaching the Camera to the Telescope All of the large format Research Series cameras are similar in configuration. The CCD head attaches to the telescope by slipping the camera's 2" nosepiece into a good quality 2" eyepiece holder. You may wish to add one or more extra set-screws to your eyepiece holder for a more secure attachment. [. . . ] 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. Technique The first consideration in capturing a flat field is to use the telescope-CCD combination in exactly the configuration used to collect the image. This means you probably have to capture the flat field at the telescope. Do not rotate the head between image and flat field, since the vignetting is usually slightly off center. Do not be tempted to build a little LED into the telescope or camera for doing flat fields; it doesn't work at all. [. . . ]