TS-Optics ONTC 303 mm f/5 Newtonian telescope - carbon tube - custom-made

[ONTC Newtonians - a unique telescope concept "Made in Germany"}]The thoroughly optimized ONTC Newtonians from Teleskop-Service combine the best mechanics and very good selected optics with unique versatility. With our help, you can put together a telescope that is optimized for you. The concept has spread around the world, especially among astrophotographers. ONTC Newtonian telescopes from Germany are in use all over the world.

The ONTC Newtonian with 303 mm aperture and 1500 mm focal length:

The telescope is a true all-rounder. The Newtonian performs very well on the moon and planets, but can also be used for astrophotography without restrictions. With suitable correctors, the speed can be increased to f/3.8 or the focal length can be significantly increased for photographing compact planetary nebulae.

The visual performance is also very good. The Newtonian is ideal as the main telescope in an observatory or for the garden. With a weight of around 18 kg (depending on the focuser), the tube can also be carried by one person.

We recommend a larger mount for the 12" ONTC, such as the EQ8, if astrophotography is on the agenda. Mounts such as the CGEM-DX or the AZ-EQ6 can also support the Newtonian, but care should be taken to set it up out of the wind.

Astrophotographic results obtained with this telescope on Astrobin

Here you can find some astrophotographs made with this telescope model: Link to Astrobin

Assembled and tested for you:

ONTC telescopes are assembled and tested for you in our company in Parsdorf. Only selected and previously approved optics are used. We attach great importance not only to the primary mirror, but also to the secondary mirror. Each ONTC is finely adjusted after assembly and tested on our optical bench before the telescope is prepared for dispatch. Each ONTC Newtonian telescope comes with a complete manufacturing protocol including star test.

Carbon tube - made in Germany

Our carbon tubes come from Germany. The tubes have a solid wall thickness and are inherently rigid. Larger tubes have a layered construction that increases rigidity and saves weight. The tubes are blackened on the inside with the blackest black (TS Black) we could find on the market. On the outside, the tubes are coated with a transparent protective lacquer, which brings out the beautiful structure of the carbon, but also protects it.

The primary mirror cell and secondary mirror cell - designed by Teleskop-Service

We attach great importance to an optimized primary and secondary mirror cell. The cells mounts are solid and hold the collimation even during transportation. The secondary mirror spider vanes are also stable and do not deform during panning. We glue the secondary mirrors in place, and no secondary mirror has ever come loose from the mount. Even with large differences in temperature, neither the primary nor secondary mirrors become distorted.

The secondary mirror is blackened on the side and back

When we build a telescope, we do it right. This includes a clean blackening of the secondary mirror. This reliably prevents reflections close to the corrector.

Solid tube rings from CNC manufacturing

The tube rings connect the telescope to the mount and also allow the installation of accessories such as a mountable camera holder or a guide scope for astrophotography. The rings are made of aluminum and are CNC-machined. They have internal threads for dovetail bars on the top and bottom. The inside of the rings is lined with velvet to prevent the tube from being scratched.

One telescope - several focal lengths for photography

Long gone are the days when there was only one coma corrector for photography. Nowadays, correctors offer a focal length extension or reduction. Reducers in particular often require a larger backfocus above the focuser. ONTC Newtonians offer up to three freely selectable focus positions, allowing you to use different correctors on one telescope and influence the focal length accordingly. Even if you later buy a corrector with a change in focal length, your ONTC will always provide you with a good basis.

Three focus positions above the 2" receptacle have proven to be very effective when working with a 2" corrector.

35 mm (ideal for visual observation and for the TSGPU, as well as the 2" PARACORR)

65 mm (standard setting for most coma correctors, like TS Maxfield, Baader MPCC ...)

90 mm (for correctors with focal reducer, like TS2Korrr)

For correctors with a larger insertion diameter, we always specify the required backfocus above the outer wall of the tube. This ensures that the corrector does not protrude into the interior of the tube, but also that valuable illumination is not wasted. We calculate the focus position with the appropriate focuser as accurately as possible and have separate tables for each corrector.

Focuser as desired

Choose your focuser from our range or even use your own focuser on your new telescope. Our unique ONTC concept makes this possible. We will be happy to advise you on choosing the right focuser.

Assembly and collimation instructions

The telescope is delivered disassembled into several units for safety reasons. Of course it is also possible to pick it up from us. On request, we can also deliver the telescope fully assembled on a pallet by a forwarding agent. Assembly and adjustment are not complicated, you can download the instructions in advance. Link to the PDF file: unc_ontc_zusammenbau_kolli_en.pdf

Astrophotographic results obtained with this telescope on Astrobin

Here you can find some astrophotographs made with this telescope model: Link to Astrobin




Astrophotos through the ONTC1215 from Gerald Hitz at  http://skyimages.at

-------------------------------------------------NGC6946 made with the TS Newtonian Telescope ONTC 1215... this newtonian telescope is equipped with the 2" Baader Steeltrack focuser. The field correcture is made with the ASA 2" Recucer / Corrector 2KORRR. More informations and a bigger version on the webpage of Wolfi Ransburg

First Light of the combination of ONTC1215 and TSKORW3 by Wolfgang Ransburg

Object: Dumbbell Nebula (M 27)

Photographer: Wolfgang Ransburg
Imaging telescope: TS ONTC1215 12" f/5 Newtonian
Field correction: TSKORW3 3" Wynne coma corrector
Filter: Optolong L-eNhance filter
Imaging camera: ASI 071MC Pro color astro camera
Exposure time: 14x250 seconds

"This image is a first test and ´first light´ with the new ONTC1215 12" f5 Newtonian from Teleskop-Service. I think the big Newtonian will have a regular place in my observatory."

Safety informations: PDF Download