{"id":15488,"date":"2026-06-24T22:00:43","date_gmt":"2026-06-24T20:00:43","guid":{"rendered":"https:\/\/deep-space-astronomy.ch\/?post_type=product&p=15488"},"modified":"2026-06-24T22:00:45","modified_gmt":"2026-06-24T20:00:45","slug":"ts-optics-gso-12-f-12-cassegrain","status":"publish","type":"product","link":"https:\/\/deep-space-astronomy.ch\/en\/product\/ts-optics-gso-12-f-12-cassegrain\/","title":{"rendered":"TS-Optics 12-inch f\/12 GSO Cassegrain"},"content":{"rendered":"

TS-Optics GSO 12\u2033 f\/12 Gen. 2 Cassegrain \u2013 304 mm Optical Tube<\/h3>\n

Visit TS-Optics 12-inch f\/12 GSO Gen. 2 Cassegrain<\/strong> is a large-aperture telescope designed for observatories, high-resolution planetary imaging, demanding visual observation, and photographic applications requiring a long native focal length. With its aperture of 304 mm<\/strong> and its focal length of 3,648 mm<\/strong>, it offers high resolving power, a bright image, and excellent contrast when observing the Moon, planets, double stars, globular clusters, and many compact deep-sky objects.<\/p>\n

This Gen. 2 version further improves mechanical rigidity thanks to a 3\u2033 RAP rack-and-pinion eyepiece holder<\/strong>, which is more stable and precise, capable of supporting heavy accessories such as a planetary camera, a filter wheel, an optical splitter, or a complete imaging system. The tube\u2019s structure carbon truss<\/strong> minimizes focus shifts and ensures excellent thermal stability, which is essential for long observation or imaging sessions.<\/p>\n

A high-performance, versatile, all-reflective Cassegrain design<\/h3>\n

Unlike a traditional Schmidt-Cassegrain telescope, this telescope uses a purely reflective optical design, with no Schmidt lens or meniscus. This design offers several significant advantages: no chromatic aberration, excellent light transmission, compatibility with infrared imaging, and faster cooling thanks to its open structure.<\/p>\n

The parabolic primary mirror and the hyperbolic secondary mirror produce a well-corrected field of view, with less field curvature than that of many compact catadioptric telescopes. Both mirrors feature a dielectric coating at 99 % for reflection<\/strong>, which maximizes the image's brightness and contrast.<\/p>\n\n\n\n\n\n\n\n\n
Optical package<\/strong><\/td>\nClassic Cassegrain telescope with a parabolic primary mirror and a hyperbolic secondary mirror<\/td>\n<\/tr>\n
Opening<\/strong><\/td>\n304 mm \/ 12\u2033<\/td>\n<\/tr>\n
Focal length<\/strong><\/td>\n3,648 mm<\/td>\n<\/tr>\n
Focus report<\/strong><\/td>\nf\/12<\/td>\n<\/tr>\n
Mirror treatment<\/strong><\/td>\n99 %: Reflections on Elementary and Secondary Education<\/td>\n<\/tr>\n
Central obstruction<\/strong><\/td>\n33 % linear<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Ideal for the Moon, the planets, and high-resolution imaging<\/h3>\n

With its native focal length of 3,648 mm, this 12-inch Cassegrain telescope is particularly well-suited for observing and imaging the Moon and the planets. Fine lunar details, Jupiter\u2019s cloud bands, Saturn\u2019s rings, and Martian features can all be observed with excellent detail when atmospheric conditions permit.<\/p>\n

The optical design, which does not include a front element, eliminates chromatic aberration and produces a very clean image, even at high magnification. For planetary astrophotography, it serves as an excellent foundation when paired with a high-speed camera, a suitable Barlow lens, and an atmospheric dispersion corrector.<\/p>\n

Another interesting instrument for compact deep-sky observation<\/h3>\n

Although the f\/12 focal ratio naturally makes this telescope well-suited for high-resolution imaging, it can also be used to photograph or observe certain deep-sky objects. Globular clusters, planetary nebulae, compact galaxies, and small targets that require a long focal length are particularly well suited to this type of instrument.<\/p>\n

Thanks to modern, highly sensitive CMOS sensors, it is now possible to take advantage of this long focal length to capture challenging subjects with a fine image scale and higher resolution than that achieved with shorter instruments. The field is well corrected and does not necessarily require an additional corrector for many configurations.<\/p>\n

Enhanced Gen. 2 mechanics<\/h3>\n

The Gen. 2 version features a 3\u2033 dual-speed RAP rack-and-pinion eyepiece holder, designed to provide greater rigidity and more precise focusing. The sliding tube is guided by ball bearings on a stainless steel rail, which improves stability under heavy loads.<\/p>\n\n\n\n\n\n\n\n
Lens holder<\/strong><\/td>\n3\u2033 dual-speed RAP with rack-and-pinion drive<\/td>\n<\/tr>\n
Focusing stroke<\/strong><\/td>\n50 mm<\/td>\n<\/tr>\n
Accessory Connections<\/strong><\/td>\n2\u2033 and 1.25\u2033 with ring clamps<\/td>\n<\/tr>\n
Additional Threads<\/strong><\/td>\nM82x1 external, M77x1 internal, M74x1 external, M69x1 internal<\/td>\n<\/tr>\n
Motorization<\/strong><\/td>\nCompatible with EAF and similar systems without an additional adapter<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Rapid cooling and thermal stability<\/h3>\n

The Cassegrain\u2019s open design makes it easier for the instrument to reach operating temperature. While some enclosed tubes may require a long thermal equilibration period, this design allows for faster stabilization, which is particularly useful in observatories or during observing sessions when the outside temperature fluctuates throughout the night.<\/p>\n

Quartz mirrors with low thermal expansion also help maintain good focus stability. For high-resolution imaging, this stability is essential: even a slight shift in focus can be enough to lose the finest planetary or lunar details.<\/p>\n

A tube designed for the observatory<\/h3>\n

With its two Losmandy-style dovetails, the tube can be easily mounted on compatible mounts. The second dovetail can also serve as a handle, an accessory mount, or a mounting base for additional equipment. The finder scope can be attached using the Sky-Watcher, Vixen, and TS-compatible mount.<\/p>\n

The generous backfocus of 350 mm from the M117x1 thread provides great flexibility for using right-angle prisms, cameras, filter wheels, optical splitters, or other imaging accessories. The included M117 extension tubes make it easy to adapt to different configurations.<\/p>\n

Key benefits<\/h3>\n\n\n\n\n\n\n\n\n\n
High resolution<\/strong><\/td>\n304 mm aperture and 3,648 mm focal length for fine lunar and planetary details<\/td>\n<\/tr>\n
Bright image<\/strong><\/td>\n99 % dielectric coating on both mirrors<\/td>\n<\/tr>\n
No chromaticism<\/strong><\/td>\nA purely reflective system without a front lens<\/td>\n<\/tr>\n
Infrared-compatible<\/strong><\/td>\nIdeal for IR imaging, particularly of planets<\/td>\n<\/tr>\n
Efficient Cooling<\/strong><\/td>\nOpen structure with fans for the primary mirror<\/td>\n<\/tr>\n
Precise Focus<\/strong><\/td>\nSturdy, geared 3\u2033 Gen. 2 eyepiece holder<\/td>\n<\/tr>\n
Mechanical stability<\/strong><\/td>\nCarbon truss tube and fixed mirrors, without primary shifting<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Technical specifications<\/h3>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Opening<\/strong><\/td>\n304 mm \/ 12\u2033<\/td>\n<\/tr>\n
Focal length<\/strong><\/td>\n3,648 mm<\/td>\n<\/tr>\n
Focus report<\/strong><\/td>\nf\/12<\/td>\n<\/tr>\n
Optical design<\/strong><\/td>\nCassegrain telescope with a parabolic primary mirror and a hyperbolic secondary mirror<\/td>\n<\/tr>\n
Reflectivity<\/strong><\/td>\n99 % on the primary mirror and the secondary mirror<\/td>\n<\/tr>\n
Central obstruction<\/strong><\/td>\n33 % linear<\/td>\n<\/tr>\n
Collimation Assistance<\/strong><\/td>\nCenter mark on the secondary mirror<\/td>\n<\/tr>\n
Mirror substrate<\/strong><\/td>\nQuartz with low thermal expansion<\/td>\n<\/tr>\n
Infrared imaging<\/strong><\/td>\nCompatible<\/td>\n<\/tr>\n
Distance Between Elementary and Secondary Schools<\/strong><\/td>\n650 mm<\/td>\n<\/tr>\n
Lens holder<\/strong><\/td>\n3\u2033 dual-speed Monorail \/ RAP with photo thread, 2\u2033 and 1.25\u2033 outputs<\/td>\n<\/tr>\n
Rear thread on the tube<\/strong><\/td>\nM117x1<\/td>\n<\/tr>\n
Distance from the M117x1 thread to the focal point<\/strong><\/td>\n350 mm<\/td>\n<\/tr>\n
Dovetails<\/strong><\/td>\n2x Losmandy-type<\/td>\n<\/tr>\n
Tube material<\/strong><\/td>\nCarbon truss and aluminum frame<\/td>\n<\/tr>\n
Internal baffles<\/strong><\/td>\nYes<\/td>\n<\/tr>\n
Weight<\/strong><\/td>\n24 kg<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Scope of delivery<\/h3>\n\n\n\n\n\n\n\n\n
Optical tube<\/strong><\/td>\nTS-Optics GSO 12\u2033 f\/12 Gen. 2 Cassegrain OTA<\/td>\n<\/tr>\n
Lens holder<\/strong><\/td>\n3\u2033 dual-speed RAP with rack-and-pinion drive<\/td>\n<\/tr>\n
Adapters<\/strong><\/td>\n2\u2033 and 1.25\u2033 connections<\/td>\n<\/tr>\n
Extensions<\/strong><\/td>\nM117 Extension Tubes<\/td>\n<\/tr>\n
Mounting<\/strong><\/td>\nTwo Losmandy-style dovetails<\/td>\n<\/tr>\n
Researcher Support<\/strong><\/td>\nCompatible with Sky-Watcher, Vixen, and TS mounts<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

For which user?<\/h3>\n

This 12\u2033 Cassegrain is designed for observers and astrophotographers looking for a large-aperture, stable, bright telescope capable of delivering excellent resolution. It is particularly well-suited for a fixed observatory, a semi-permanent setup, or an experienced user wishing to utilize a long focal length for planetary, lunar, and compact deep-sky objects.<\/p>\n

It requires a sturdy mount capable of comfortably supporting its 24 kg weight, along with the associated accessories. Once properly set up and aligned, it becomes an extremely powerful instrument, capable of delivering highly detailed images and a truly impressive observing experience.<\/p>\n

Our opinion<\/h3>\n

The TS-Optics GSO 12\u2033 f\/12 Gen. 2 Cassegrain is a very attractive alternative to large-aperture Schmidt-Cassegrain telescopes. Its purely reflective design, lack of a front element, quartz mirrors, 99 % coating, and reinforced eyepiece holder make it a particularly well-suited instrument for high-resolution imaging.<\/p>\n

This is a challenging but highly rewarding optical tube. For an advanced amateur, a club, a private observatory, or an educational institution looking for a powerful telescope for observing the Moon, the planets, and compact objects, this 12\u2033 Cassegrain offers an excellent balance between aperture, focal length, mechanical sturdiness, and image quality.<\/p>","protected":false},"excerpt":{"rendered":"

TS-Optics GSO 12″ f\/12 Cassegrain Gen. 2 \u2013 Tube optique 304 mm Le TS-Optics GSO 12″ f\/12 Cassegrain Gen. 2 est un t\u00e9lescope de grand diam\u00e8tre con\u00e7u pour les observatoires, l\u2019imagerie plan\u00e9taire haute r\u00e9solution, l\u2019observation visuelle exigeante et les applications photographiques n\u00e9cessitant une longue focale native. Avec son ouverture de 304 mm et sa focale […]<\/p>\n","protected":false},"featured_media":15489,"comment_status":"open","ping_status":"closed","template":"","meta":[],"product_brand":[842],"product_cat":[751],"product_tag":[],"class_list":["post-15488","product","type-product","status-publish","has-post-thumbnail","product_brand-ts-optics","product_cat-cassegrain","first","on_supplier","taxable","shipping-taxable","purchasable","product-type-simple"],"_links":{"self":[{"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/product\/15488","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/types\/product"}],"replies":[{"embeddable":true,"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/comments?post=15488"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/media\/15489"}],"wp:attachment":[{"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/media?parent=15488"}],"wp:term":[{"taxonomy":"product_brand","embeddable":true,"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/product_brand?post=15488"},{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/product_cat?post=15488"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/product_tag?post=15488"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}