MODEL CFW-8A COLOR FILTER WHEEL
For all models of ST-7/8/9/10/2000 Cameras

Model CFW-8 Color Filter Wheel

SBIG pioneered tricolor imaging for amateurs by developing hardware and software to register and color balance Red, Green, and Blue images that display spectral emission of deep space objects. When interference filters are carefully selected to match the spectral regions of ionized gases the images taken through the filters can be summed together to represent the distribution of these gases. SBIG designed the following interference filters for use with the CFW-8A:

Color Filter Passbands

Tricolor images are taken through the CFW-8A Color Filter Wheel and processed with CCDOPS, CCDSoftV5, or third party software.  The primary color images are taken through Red, Green and Blue filters. After the images are taken they are processed with the software to co-align the Red, Green and Blue images. The co-aligned image is then color balanced on the computer monitor to become a tricolor RGB image, which can then be saved to disk.   A similar process is used to make LRGB images except that a greyscale luminance image is added for detail.  CCDOPS software also allows the user to perform image processing functions such as smoothing and sharpening as well as saving images in TIFF format.  The raw images can also be saved in a variety of formats for export to any of the many commercially available software programs for color image processing such as Maxim DL and Photoshop.

The CFW-8 system is designed to be "direct connected" to the Models ST-7/8/9/10/2000 imaging cameras for a thinner, more rigid mounting.  An optional male-to-male t-thread adapter is also available allowing easier (but less rigid) attachment and detachment for occasional use.  On the front end a variety of optional T-Thread accessories are available including 1.25 inch and 2 inch diameter nose pieces as well as a "Visual Back Adaptor" for direct connection to SCT's.  A new optional accessory is the AO adapter plate which makes it possible to firmly connect the camera, filter wheel and AO-7 without using a screw-in t-thread adapter.

The CFW-8 is operated through the CCDOPS software and utilizes a closed loop stepper motor system with positional accuracy of  ±0.01 inches. It holds up to five standard 1.25" diameter thread-in filters. Also supplied with the unit are Red, Green, and Blue (RGB) interference filter sets and a clear filter (focusing). The new SBIG RGB filters also block Infrared (IR) so an inline IR Blocking filter is no longer required. These filters are mounted in standard size cells that normally fit into 1.25" eyepiece barrels. The CFW-8 adds back focus of approximately 1 inch.

Although some examples of tricolor imaging are shown in this catalog it is difficult to display the wide range of techniques that our customers have developed. The CFW-8 can produce photographic quality tricolor images that rival color astrophotographs.   However, these RGB images also contain an entirely new and added level of valuable information; the identification and distribution of different ionized gasses in an object. SBIG also furnishes precision UBVRI filter sets with the Model CFW-8, filters which allow the user to perform color photometry to measure the classification and temperature of objects.

Red Image	Green Image
Blue Image	Combined Image
Note: The three separate Red Green and Blue CCD images are not identical. Each one displays only the spectral region that the filter allows to pass. Since each filter corresponds to a known spectral region the combined image displays the distribution of those ionized gases.