6" f/12 Classical Cassegrain Telescope by GSO
Cassegrain telescopes combine the benefits of a Newtonian telescope being a pure reflective system with a short-built design. In terms of optical quality, Cassegrain telescopes are superior to customary Schmidt-Cassegrain systems. Cassegrain telescopes are mainly used for photography of the moon and the planets and for observation of astronomical objects. Thanks to the highly sensitive sensors built into modern astro cameras, even deep-sky photography of nebulae, star clusters and galaxies is possible.
The advantages of GSO Cassegrain Telescopes in summary:
Large corrected and illuminated image field due to parabolic primary and hyperbolic secondary mirror with less field curvature than with SC telescopes.
Pure reflection system without Schmidt plate, as a result even Infrared photography becomes possible at full sharpness.
Significantly quicker temperature adaption than a SC, due to open design.
Brighter image due to 96% dielectric coating on primary and secondary mirror.
No shifting, because the primary mirror is fixated
High-quality 2" Crayford focuser with micro-gear reduction and compression rings for 2" and 1.25" accessories
33% obstruction caused by secondary mirror, comparable to SC telescopes.
Better sharpness on the optical axis due to precise mirror surfaces and the lack of a Schmidt plate
Less problems from dew: with Schmidt-Cassegrains you get condensation on the front plate, not with a Cassegrain
Interior baffles for even higher contrast
Generous backfocus allowing the use of 2" accessories.
Compact tube with only 500 mm length - can be operated with smaller mounts
Significantly less expensive than other classical Cassegrain telescopes!
Cassegrain Optics are versatile Telescopes
Mobile travel scope:
Take the compact and light telescope with you to your traveling location. It only takes a few seconds to unscrew the focuser, making the Cassegrain even more compact and fitting your hand luggage.
Telescope for observation of Astronomical Objects:
Due to the bright and contrasty image and also because of the large corrected and illuminated image field, the Cassegrain is optimal for observation of astronomical objects. 2" and 1.25" accessories are not a problem. The obstruction by the secondary mirror is only 33%. This is comparable to Schmidt-Cassegrain telescopes. As a result of the 96% reflection of primary and secondary mirror the image is significantly brighter. Even the field sharpness is better, because the image field is basically undistorted.
Telescope for Astrophotography:
The Cassegrain is very well suited for photography of the moon and the planets. The visual contrast is very high. Due to interior baffles stray light is effectively suppressed. Planets and tiny moon craters can be seen without the slightest chromatic aberration. Thanks to its micro-gear reduction the Crayford focuser permits precise focusing. When using modern, highly sensitive CMOS cameras, even deep-sky photography becomes possible with the GSO Cassegrain. An additonal correction lens isn´t needed, because the image field is well corrected up to APS-C sensor format.
Twilight I Adjustable AZ Mount
The Twilight II is a light-to-medium-duty alt-azimuth mount and tripod designed to quickly and easily accept small to medium sized refractors, such as the AR102 or ED102mm, and of course, the ED80mm. Lightweight, fast Newtonians will also match up nicely with the Explore Scientific Twilight I mount. As long as your telescope does not exceed 18 pounds and has a Vixen-Style Universal Dovetail bar for mounting the telescope to the mount head, you are good to go.
The Twilight II alt-azimuth mount head is made of powder-coated aluminum and there are worm gears on both axes. The adjustable angle head can be tilted forward or back at a 45° angle to allow more clearance for your telescope so you can point it straight up for viewing at the zenith.
Slow-motion control cables are attached on the vertical and horizontal axes, and are easy to turn during the night, even with gloves on, due to the over-sized knurled knobs that are attached to the end of each cable. They can be attached to either side of each axis to accommodate right or left-handed users, or different types of telescopes (e.g. refractors vs. Newtonian reflectors) for ease of adjustment.
The stainless steel tripod that comes standard with the Twilight I mount has adjustable legs and a wide foot print of 42 inches, which makes the tripod more stable. A spreader bar locks against the inside of the legs to secure the tripod even further, and keep vibrations to a minimum.
In The Box
6" f/12 Cassegrain Telescope
Choice of 2 Plossl Eyepieces
GSO 6x30 Achromatic Finderscope
2" focuser with reduction to 1.25"
Dovetail GP Level
Dust protection cap for the focuser and front aperture
Finder shoe (mounted)
M90 extension tubes
German Collimation Manual
Twilight Mount
Height Adjustable Tripod
Gearing Knobs