The STF-8300 Self-Guiding Package includes the new ST-i autoguider and new low profile, wide field Off-Axis Guider (OAG), which allows self-guiding. The OAG is designed with a 7-element relay lens system that places the position of the guide camera to the side of the main camera and filter wheel, which minimizes the impact on overall backfocus. The same lens system also acts as a 0.7X focal reducer that doubles the field of view of the guide camera compared to a typical off-axis system. The OAG adds only ¾ in. (19mm) backfocus to the camera and filter wheel. The guide camera can also be rotated in 90 degree increments. The OAG can be used on both mono and color cameras (with appropriate adapter) and is 100% backward compatible with all ST-8300 cameras.
The Self-Guiding Package also includes the 5-position FW5-8300 filter wheel for 36mm filters.
The new Model STF-8300 is SBIG's second-generation camera using the popular KAF-8300 CCD. The STF-8300 has new, faster, electronics with 10-megapixel/second digitization rate and a full frame image buffer. The high resolution image downloads in less than one second. The camera uses SBIG's traditional even-illumination, photometric shutter design, and adds a user rechargeable desiccant plug.
The new ST-8300M (monochrome) and ST-8300C (color) cameras are based on Kodak's KAF-8300, 8.3 megapixel, full frame CCD. This CCD array has 3326 x 2504 pixels at 5.4 microns making it ideal for both short fast optics in high resolution (unbinned) mode, and for longer focal lengths it can be binned binned 2x2 or 3x3. The CCD has both antiblooming and microlens technology to improve the effective Quantum Efficiency of the sensor. As a result it can be used in a wide variety of optical configurations. The camera electronics are USB 2.0 for fast download rates and rapid focus mode. The small light body accepts both c-mount and standard 35mm Nikon camera lenses. In addition to its imaging capabilities, it can also be used as a guider. A built-in mechanical shutter is included for automatic dark frames.
Large High Resolution Imaging CCD. The KAF-8300 CCD is approximately 18 x 14mm and has a diagonal measurement of about 22 millimeters. This is about 1.6X the image area of an ST-10 and nearly the same area as the STL-4020M. With its relatively small pixels and large image area it is ideal for wide field imaging with short fast refractors. Binned 2x2 the pixels are 10.8 microns square and binned 3x3 they are 16.2 microns square. At 2x2 the array is still 2 megapixels and at 3x3 just under one megapixel. This feature makes it possible to match the pixel size to your seeing and scope, from a small refractor to a large SCT. For most users, binning will not only help optimize the sensitivity of the CCD with their optics but also speed up the download rate.
USB 2.0 Interface: The STF-8300 will download a full frame in less than 1 second when connected to a high speed USB port.
I2C Accessory Port: The 9-pin I2C port allows the use of SBIG filter wheels with the same interface. The power and commands for the filter wheel all come from the camera through this port, so there are no other cables or power supplies needed to operate the filter wheel. Also, the same software that controls the camera also controls the filter wheel. Automatic RGB exposure sequences may be set or the user may control the filter wheel for each exposure.
Mechanical Shutter: A mechanical shutter is included to facilitate dark frames. This is a necessity for anyone operating remotely, even if remotely means a few feet away from the telescope.
TE cooling: In SBIG's initial tests the camera reached a maximum of -40 degrees C below ambient in a warm room. A few degrees were then given up for regulation with the camera running at only 70% TE cooling power to maintain -36 degrees C below ambient. Because of the CCDs extraordinary low dark current, great temperature deltas are not required to achieve a dark current low enough that it becomes relatively insignificant compared to the background sky brightness. In ne test, one 15 minute dark frame at -10C was subtracted from another at the same temperature. The noise remaining was a total of 15 electrons, including read noise, in this 15 minute exposure. This is exceptionally low.
36mm Filters and Filter Wheel: Due to the large size of this CCD, typical 1.25" filters are just too small to fully cover the sensor without some vignetting in the corners. This may be acceptable at f/7 or longer focal lengths, but at shorter focal lengths the effect becomes greater. For this reason SBIG offers a new 5-position filter wheel that will hold 36mm filters. Full sets of 36mm filters are available for this camera from several filter suppliers: Astrodon, Baader and Custom Scientific.