Description
The supplied light-duty Crayford focuser can be unthreaded from the focuser attachment collar, allowing you to use another focuser. One popular choice is the dual-speed 3″ diameter 1.5″ travel Feather Touch #3015 rack and pinion focuser, available from your Astro-Tech dealer.
The newly designed focuser attachment collar is bolted rigidly to the back plate of the AT12RCT, completely independent of the primary mirror and baffle tube. This allows it to be collimated separately from the primary and secondary mirrors if needed, using the built-in focuser collimating ring. The focuser attachment collar has a male 117m x 1mm pitch thread for attaching the focuser.
The Feather Touch #3015 normally comes with a 109mm threaded collar for connecting to a scope. Using the #3015 with the AT12RCT therefore requires an optional #M117x1 Feather Touch adapter. The #M117x1 adapter threads onto the focuser attachment port. The #3015 focuser (without its 109mm collar) then slips into the #M117x1 adapter and is held in place by three large brass Delrin-tipped retaining knobs. Only focusers with a maximum 1.5″ drawtube travel, such as the Feather Touch #3015, are recommended for use with the 12″ Astro-Tech AT12RCT Ritchey-Chrtien. For other focusers, such as a MoonLite, contact the focuser manufacturer for an adapter to fit the 117mm x 1mm port on the rear of the scope.
To fine-tune the 288mm back focus of the AT12RCT to the requirements of your camera and equipment train, three threaded extension rings (one 2″ and two 1″ in length) are provided to thread singly or in combination between the 117mm port on the AT12RCT rear cell and the focuser of your choice. These provide a flex-free solid metal extension that changes the distance between your chosen focuser and the rear cell. This lets you accommodate the varying back-focus requirements of DSLR-type camera imaging versus long equipment train CCD imaging. The 2″ threaded ring weighs 14.4 ounces, the 1″ rings weigh 7.2 ounces each.
Cooling fans: To allow the AT12RCT 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.
Two dovetail mounting rails: Two 14″ Losmandy-style “D-plate” dovetail rails are bolted to the top and bottom of the center and rear truss-tube support rings. These allow you to install the AT12RCT directly on an equatorial mount and mount optional accessories (such as rings for a photoguide scope that attach 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.
Other accessories: This new Version A of the AT12RCT includes slip-on dust covers for both the primary and secondary mirrors. Also included is a mounting shoe for a red dot-type finder, such as the Astro-Tech ATF. The mounting shoe can also accept the Astro-Tech ATF50QRB 50mm finderscope quick release bracket.
Tech Details:
| Aperture | 12″ |
|---|---|
| Focal Length | 2432mm |
| Focal Ratio | f/8 |
| Heaviest Single Component | 49.8 pounds |
| Weight | 52 lbs. |
| Resolution | 0.38 arc seconds |
| Telescope Type | Ritchey-Chrtien |
| Warranty | 1 year |
| Back Focus | 11.33 (288mm) from rear cell |
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