Astronomy Technologies Astro-Tech 6" f/9 Ritchey-Chrétien Astrograph

This AT6RC Ritchey-Chrétien astrograph has:

• 6" f/9 true Ritchey-Chrétien hyperbolic mirror optical design
• 1/12th wave or better BK-7 mirrors
• enhanced aluminium optical coatings
• dual-speed Crayford focuser
• 2" and 1.25" compression ring eyepiece holders
• Vixen-style dovetail plate

True Ritchey-Chrétien telescopes typically start at well over £6,000, putting them out of the
reach of most astrophotographers. At least, true R-Cs used to start at £6,000 and up.

Introducing the Astro-Tech AT6RC, an incredibly affordable Ritchey-Chrétien astrograph that
virtually all astrophotographers can afford!

The Astro-Tech AT6RC makes the coma-free imaging of a true Ritchey-Chrétien optical
system available to amateur astronomers using webcams, Deep Sky Imager-type cameras,
and SBIG ST-7/8/9/10/2000-class CCD cameras. And it does it at a price less than that of
even the least-expensive SBIG CCD camera. Featuring a true Ritchey-Chrétien optical
system, this incredibly economical 6" Astro-Tech R-C makes you wonder just what those
£6,000+ R-Cs have that makes them cost so much.

Designed strictly for exceptional imaging, the Astro-Tech AT6RC provides the wide coma-
free photographic field that astrophotographers crave, but can’t get from conventional
reflectors and Schmidt-Cassegrains. Likewise, as a pure two-mirror system, the AT6RC is
totally free from the spurious color that affects the imaging of all but the most costly
apochromatic refractors, and it does it with an 6" aperture that equals or exceeds the light
gathering of most apo refractors.

If serious astrophotography is your goal, but the price of most true Ritchey-Chrétien optics
has been keeping you from the optical design most modern professional observatories and
the Hubble Space Telescope use for their imaging, your wait is over. The Astro-Tech AT6RC
can bring the world of professional deep space imaging to your backyard observatory at a
truly affordable price.

The AT6RC is ideal for coma-free imaging with webcams, Deep Sky Imager-type cameras,
and ST-7/8/9 class CCD cameras.

This Astrograph’s Optical System . . .

Optical design: true Ritchey-Chrétien Cassegrain-type two-mirror optics, with hyperbolic
primary and secondary mirrors. For more details, click on the “optics" icon above.

Aperture: 6", 1370mm focal length, f/9 focal ratio.

Primary mirror: Made of BK-7 optical glass. Polished to 1/12th wave or better surface
accuracy. Unlike designs 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 AT6RC primary mirror is
fixed to eliminate image shift and focus changes.

Secondary mirror: Made of BK-7 optical glass. Polished to 1/12th wave or better surface
accuracy. Mounted in a four-vane spider and fully collimatable using simple standard
Schmidt-Cassegrain collimating techniques. Unlike complicated R-C designs that use motors
to move the secondary mirror fore and aft to focus, the AT6RC secondary mirror is fixed and
focusing is done externally.

Enhanced aluminum optical coatings: Both primary and secondary mirrors have enhanced
aluminum mirror coatings, overcoated with a protective layer of quartz for long life. Reflectivity
is in the 96% range, the same as those $10,000+ R-C scopes.

Optical tube: Aluminum, with die-cast and machined aluminum front and rear cells.

Internal light baffles: Computer optimized primary and secondary baffling. Contrast-enhancing
glare-stop baffles in the optical tube, with multiple glare-stop microbaffles in the secondary
mirror light shield and primary mirror baffle tube to provide truly dark sky backgrounds during
imaging.

Dual-speed Crayford focuser: The non-vignetting focuser has dual-speed focusing. There are
two coarse focusing knobs. The right knob also has a smaller concentric knob with a 10:1
reduction gear microfine focusing ratio. This provides exceptionally precise image control
during critical CCD imaging. All focus knobs are ribbed, so they are easy to operate, even
while wearing gloves or mittens in cold weather.

Compression ring eyepiece holders: The focuser drawtube ends in a 2" eyepiece 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. 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" eyepiece holder on the eyepiece holder
rotation mechanism, the 1.25" adapter also uses a non-marring soft brass compression ring.

Mounting dovetail: removable Vixen-style dovetail bar running the length of the underside of
the optical tube.

Other accessories: A slip-on dust cap is standard.

Two year warranty: As an expression of the confidence Astronomy Technologies has in the
quality of their products, the Astro-Tech AT6RC is protected by a two-year limited warranty
against flaws in materials and workmanship (shipping case excluded).

AT6RC - £899.00 + £10.00 shipping & insurance.

AT8RC:
An 8" f/9 R-C astrograph for imaging with 35mm large format (STL-type) CCD cameras and
long imaging equipment trains. Carbon fibre tube, quartz mirrors, dielectric mirror coatings,
1/12th wave or better optics, Feather Touch focuser, carrying case, dovetail bar and dust
covers.

AT8RC - £2049.00 + £10.00 shipping & insurance.

AT10RC:
A 10" f/9 R-C with the same features as the AT8RC, but larger, plus the addition of cooling
fans.

AT10RC - £3449.00 + £10.00 shipping & insurance

12" and 16" Astro-Tech Ritchey-Chrétiens under development. Prices to be announced.

The Astronomy Shop

1 Tone Hill. Wellington

Somerset TA21 0AU

United Kingdom

Telephone: +44 (0)1823 665510