TS-Optics ONTC 250 mm f/4 Carbon Photo Newtonian with conical primary mirror and 2 inch RAP focuser - Lightweight construction

ONTC 10" f/4 ONTC Newtonian Telescope with 2" RAP Focuser

This Newtonian has been developed from the proven ONTC telescope series. Here, too, only the best mechanics and selected optics were used. The result is a well thought-out telescope for astrophotography, but also for observation. At only 11.45 kg, the Newtonian is a lightweight and is still supported by transportable mounts such as the EQ6. Nevertheless, the Newtonian offers very high stability thanks to the solid primary mirror cell and secondary mirror mount. The telescope can even withstand rough transportation without losing collimation.

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 shipment. Of course, a checklist is included.

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.

Very good internal blackening with TS-Black for maximum contrast

Our ONTC Newtonian telescopes use the TS-Optics "Black" anti-reflective paint. The inside of the tube is darkened just as well as with the velour film. The illustration on the left shows the difference between the familiar school blackboard paint and the TS anti-reflective paint.

Solid tube clamps from CNC machining

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

Conical primary mirror made of quartz glass - many advantages

The mirror is lighter than conventional mirrors and cools down faster and more evenly. The annoying holding clamps are no longer required, and with them the diffraction effects on the star. The full aperture of the mirror can therefore be used. Overall, the mounting is also less susceptible to distortion of the mirror.

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 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.

These three focus positions above the 2" receptacle have proven to be very useful when working with a 2" corrector. The ONTC is already equipped with these positions.

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

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

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

Assembling and collimation instructions

As a safety precaution, the telescope is delivered disassembled into several assemblies. Assembly and adjustment are not complicated, you can download the instructions in advance. Link: unc_ontc_zusammenbau_kolli_en.pdf