Features of this Astro-Tech AT10RC Astrograph . . .

* Optical design: true Ritchey-Chrètien Cassegrain-type two-mirror optics, with hyperbolic primary and secondary mirrors. The 235mm available back focus allows for the use of long CCD equipment trains.

* Optical specifications: 10" aperture, 2000mm focal length, f/8 focal ratio.

* Hyperboloid primary mirror: Made of low thermal expansion quartz. Ground and polished under precision computer control. Unlike catadioptric designs (SCTs, Maksutovs, etc.) that move the primary mirror fore and aft in the optical tube to focus (which can lead to image shift as the mirror position changes) the AT10RC primary mirror is fixed to eliminate both a catadioptric's image shift and the frequent primary mirror collimation requirements of a Newtonian reflector.

* Hyperboloid secondary mirror: Made of low thermal expansion quartz, rather than the Pyrex used by competitors. Ground and polished under precision computer control. Mounted in a four-vane spider and fully collimatable using simple standard Cassegrain reflector collimating techniques. Unlike complicated R-C designs that use motors to move the secondary mirror fore and aft to focus, the AT10RC secondary mirror is fixed and focusing is done externally.

* 99% reflectivity dielectric coated optics: Both primary and secondary mirrors have non-tarnishing state-of-the-art multi-layer dielectric mirror coatings. These have a full 99% reflectivity for the brightest possible images. This is higher than the unspecified reflectivity (but typically 94-96% reflectivity) of the enhanced aluminum coatings used by competitors.

* Multiple internal light baffles: Computer optimized primary and secondary baffling. Nine contrast-enhancing glare-stop knife-edge baffles in the optical tube; multiple glare-stop microbaffles in the secondary mirror light shield; and baffles in the primary mirror baffle tube to provide truly dark sky backgrounds during imaging.

* Cooling fans: To allow the AT10RC to reach ambient temperatures more quickly for optimum imaging performance, there are three small low vibration/high CFM primary mirror cooling fans built into the rear cell. The high speed DC fans are powered by a standard equipment battery pack that plugs into a jack on the rear cell. The battery pack uses eight user-supplied AA batteries. An optional external DC power supply, such as a rechargeable 12VDC battery pack can also be used to power the fans.

* 1.25" and 2" compression ring accessory holders: The 3.25" o.d. focuser drawtube ends in a stepdown to a 2" accessory holder that uses a non-marring soft brass compression ring to hold 2" imaging accessories in place. The compression ring won’t scratch the barrel of your accessories as an ordinary thumbscrew can. Two thumbscrews are provided to lock the compression ring on your accessories. Also supplied is a 1.25" accessory holder that slips into the 2" compression ring holder to let you use 1.25" imaging accessories. Like the 2" accessory holder on the drawtube, the 1.25" adapter also uses a non-marring soft brass compression ring.

* Two dovetail mounting rails: Two Losmandy-style "D-plate" dovetail rails are provided for installing the AT10RC on an equatorial mount, as well as for mounting optional accessories (such as rings for a photoguide scope) on top. The 21" long dovetail rails run the length of the optical tube. One is mounted underneath the tube for installing the 34.4 pound AT10RC directly on a suitable payload capacity Losmandy-style equatorial mount. The second dovetail rail is mounted 180° away from the first, on top of the tube. This can be used for installing a photoguide ring set, piggyback camera adapter, or any other accessory that attaches to a scope by means of Losmandy-style "D-plate" dovetail adapters. The undersides of the dovetails have been hollowed out to lighten their weight without compromising their strength, as can be seen in the side-view feature image below.

* Finderscope dovetail: a Vixen-style finderscope bracket dovetail base is installed on the upper left side of the optical tube. It can easily be removed if not needed. It will accept Vixen-style finderscope brackets as well as red dot-type finders.

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