The STL-11000M cooled astronomical CCD camera, manufactured by SBIG (Santa Barbara Instrument Group), is a large-format (35mm fullframe-size) monochrome camera intended for long-exposure astronomical imaging. This has been one of the most popular astro-imaging cameras in the past 2-3 years, although it is now being superceded by even larger format cameras (the STL-11000 CCD chip measures 24x3 6mm; some of the newer chips are much larger - for example, the Kodak 16803 measures about 38x38 mm and has 16 megapixels). The larger size of the STL-11000 (compared to APS and smaller chips) provides a wider field-of-view, regardless of which scope is used. For example, while the ST-4000XCM (approx. 15x15 mm chip) has a roughly 16x16 arcminute field-of-view with my 12" LX200R (at 3200 mm FL), the STL-11000 provides a roughly 24x36 arcminute field-of-view - so about double in one axis, and 1.5X in the other axis. This aids both in framing images, as well as finding suitable (bright enough) guide stars. The pixel size of the STL-11000 is 9 microns, which gives a plate scale of about 0.57arcseconds per pixel. [the formula for "Plate Scale", or FOV per pixel, is 206*pixelsize (microns)/focal length (mm)]. Although the STL-11000M is a monochrome chip and uses external filters for obtaining a color image, the basic chip still has relatively low sensitivity - especially in the red and near-IR portions of the spectrum. In fact, it is actually relatively close to the characteristics of the chip used in the ST-4000XCM. These chips are manufactured by Kodak; the ST-4000XCM uses the KAI-4020 chip (which has now been replaced by the improved KAI-4022 chip), and the STL-11000M is bsaed on the KAI-11002 chip. The STL-11000 resolution is 4008x2672 pixels (each 9 microns square), and the diagonal (which should be covered by the image circle of the telescope) is 43.4 mm. As the STL-11000M is a monochrome camera, special color filters are needed to create a color image; the camera has an internal filter wheel that holds 5 filters - currently L (luminance), R (red), G (green), B (blue), and Ha (hydrogen alpha). A larger filter wheel (FW8-STL) is available which can hold up to 8 filters, allowing OIII and SII narrowband filters to be mounted along with the LRGBHa filters, so that full-color narrowband images can be made. I bought this camera (as well as most other pieces of astrononomical equipment) used, through Astromart, from a well-known imager, Randy Nulman (this camera was part of his system at New Mexico Skies). It is a Class 1 camera, meaning that it has no column defects, and limited pixel defects. However, I am finding that it still has a large number of "bad" pixels - i.e., that are nearly complete white or black regardless of exposure; these need to be removed via either Dark subtraction or bad pixel map. |
 | This is what the SBIG STL-series cameras look like (without AO and cables). The bolt-on faceplate provides a 2.156"x24tpi screw thread for attachment to the scope or other accessories. There is also a bolt-on faceplate with a 2" nosepiece that fits into any eyepiece holder (or focuser). Various adapters can be used to convert the 2.156x24 thread to a dovetail, Nikon lens, metric threads, or other attachment methods of the various accessories to be used with the camera. You can see that the [thinner] front portion of the housing is bolted on to the main body of the housing; that upper portion incorporates the 5-position electronic filter wheel. Separate filter holders may be obtained from SBIG to have several different sets of filters ready. For example, one could have a LRGBC (luminance, red, green, blue, and clear) filter set; a LHaOIIISII narrowband filter set; and a UVBRI (photometric) filter set. However, it is a hassle to remove the camera, take off the AOL accessory, remove the front part of the housing, and change filter wheels. You can see the electrical connectors on the bottom of the camera (to the left), as well as water cooling quick-connect ports (I'm too nervous about water around my equipment and electronics to use water cooling, which is only helpful in the summer). On the right side in the photo, there is a line of LED indicators that show power and various lower voltage levels as a caution (e.g., if operating from batteries in the field). The handles at the rear of the camera can be left on or removed at the option of the user. |
This image shows the STL-11000M camera with the AO-L (large format adaptive optics system) mounted to the Pyxis rotator - which is, in turn, mounted to the TCF-S focuser, which is connected to the back of the 12" LX200R scope. Note how much larger the STL-series cameras are, compared to the ST-series (you can see the ST-4000XCM attached to the Megrez 90 above the STL camera). An Optec dovetail is mounted on the front of the AO-L for attachment to the Pyxis rotator. This makes for a rather large and heavy optical train which would be inappropriate for small scopes. However, I am finding vignetting that might even argue for using a 3" focuser and 3" rotator, rather than the 2" Pyxis and TCF-S; this would be much heavier than what I have now! Cables run between the STL camera and the AOL; between the camera and the remote guide head; and from the camera (through the mount) to the power supply and computer. A separate [ST-4 standard] guiding cable is connected between the camera and the mount itself.
|  |
 | To the left you can see the basic specs for the KAI-11002M chip, as provided by SBIG. With my 12" LX200R scope at 3200 mm focal length, the pixel size is about 0.57 arcseconds; with 4008x2672 pixels, the total field-of-view ("FOV") of this chip is about 26x39 arcminutes. Using this camera with my FSQ-106ED (at a focal length of 530 mm), the pixel size is about 3.5 arcseconds, so the FOV is about 2.6x3.9 degrees (i.e., 6X wider FOV than with the 12" LX200R). Antiblooming is the ability of the receptors on the chip to be overloaded with light, and still not "bleed" through to other pixels. Without antiblooming, bright stars can have a line through them that must be removed in processing. As shown in the detailed specs below, the "blooming supression" of this chip is about 1000X - which means that the chip can receive 1000X more light intensity than would be necessary to reach 65000 ADU (the maximum capacity of each pixel of the camera), and still produce nice small round stars. Non-antiblooming cameras are usually used for precise photometric studies, where image aesthetics are unimportant. |
Here are the basic specifications for the Kodak KAI-11002M chip used in the STL-11000 camera. The peak quantum efficiency ("QE") of 50% is not particularly good (some chips have up to 90% QE). The Kodak specification sheet for the KAI-11002 chip can be found HERE.. |  |
 | As noted above, the "peak" QE is 50%. However, the QE falls rapidly at both longer and shorter wavelengths, as shown in the spectral sensitivity curve to the left (black line). So at the (approx) 656nm wavelength of hydrogen alpha light, the KAI-11002M chip has less than 30% QE. Thus, while the STL-11K allows use of both RGB filters and narrowband filters (Ha, OIII, SII), the sensitivity to Ha wavelengths is more than a factor of 2X less than some other cameras that are currently available. The colored curves to the left are the spectral characteristics of the Bayer matrix filters that are used on the color version of this chip, the KAI-11002C (used in the SBIG STL-11002C camera). You can see that they reduce the maximum QE at the shorter wavelengths (e.g., in the blue and green) by nearly 20%. |
And here are the mechanical specs for the STL-series cameras. Note that the weight of the camera is 4lbs, and this doesn't include the AO, rotator, and focuser - so the entire image train probably weighs close to 8 lbs, with all the adapters, and other hardware required. If not tied-off properly, the electrical cables can add further "weight" to the system. For safety, it is highly desirable that 1) all connections use dovetails or screwed-on flanges, not set-screws; and 2) there should always be a "safety cable" (string, rope, wire) that prevents the camera from falling to the ground, in the event that something comes loose and separates the camera or other parts of the image train. In my early experience with an ST-4000XCM, at least 2-3 times, I watched on the remote video monitor (from my office), as the camera fell out of the back of the scope (!!!). I nearly had heart attacks each time, but fortunately, I had safety cables, so the camera never touched the ground (or the mount), and never got damaged. However, this definitely taught me a lesson, and you will always see safety cables on my cameras! |  |
SBIG STL-11000M Class 1 large format cooled dual-chip monochrome astronomical CCD camera description specifications images with AO-L