SBIG Aluma 8-Position Self-Guiding Filter Wheel
Self-Guiding 8-Position Filter Wheel for the Aluma Series cameras. Same as the Standard filter wheel but with a guiding CCD and associated optics built into the front cover, in front of the filters. Due to the additional backfocus requirements, camera lens adapters will not work with this cover. A standard cover is available as an accessory. The standard cover is easily swapped for the self-guiding cover when imaging through a camera lens is desired.
A new filter wheel design for the Aluma series sets it apart from other designs. The carousel holds eight 36mm filters and inserts are available for 1.25" filters. Two new unique features make this an imager's delight: First, the design incorporates a self-guiding CCD in the filter wheel cover so that light from the guide star is captured before passing through the filters. An optional filter wheel cover is available for wide angle imaging with Nikon or Canon 35mm camera lenses, or for anyone who does not need or want the built-in self-guiding. Full sets of 36mm LRGB and Narrowband filters by Astrodon, Baader Planetarium, and Astronomik are available for un-vignetted imaging at any f/ratio.
The second unique feature of the Aluma filter wheel is a positive centering mechanism that precisely re-positions and firmly holds filters in exactly the same position over the CCD every time, regardless of a loss of power or intervening movement of the filter wheel.
In SBIG's tests of the new design, using an Aluma-8300, 814, or 614, the re-positioning of the filters was accurate to better than 5.4 microns after several complete rotations of the filter carousel. This degree of precision means that flat fields taken after the filter has moved and returned are accurate to a single pixel.