DK 250

The NortheK DK 250 is the preferred solution for visual and photographic hi-res observation of small angular dimension objects, such as surfaces and Moon, planet.

NortheK has taken the challenge to implement this optical design, normally intended for amateurs, with its mechanical and composite material technologies.

A  slightly lower price than  the Classical Cassegrain makes it more affordable for the customer who wants a dedicated hi-res instrument.

As usual, we didn’t compromise   on quality.  The primary mirror has an f/3 focal ratio; just as in the Classical Cassegrain, because we consider and do our best accomodate the needs of the amateur astronomer for a compact , lightweight and good quality O.T.A. to be carried around.

A very specialized, top range instrument, on wich any  Solar System avid observers can rely (and that will give them all the enjoyment and satisfaction possible with this diameter)



The DK 250 from NortheK is a very  high quality reflector telescope with a Dall-Kirkham optical scheme (parabolic primary and convex spherical secondary).

As per any other 250 mm. opening model from NortheK, the tube is the high peforming UnitorK with StabilobloK cell and secondary support AxyS, all of  them being made on projects owned by NortheK.

As per the classic Cassegrain, the field has been kept at 30 mm. diameter, a bit over-specified for the duties of this O.T.A. but certainly very interesting for large lunar surface shots.

Considering the price of a modern and high performing telescope, NortheK believe their customers should not compromise on any aspect when buying an instrument, that is why they offer for the DK 250 engineering as accurate as for the instruments with larger diameter and higher performance.

The back focus is 250 mm. as the NortheK RC 250 and CS 250. There is space enough to attach whatever you need to your Dall-Kirkham sc as accessories, filters-holders wheels, joints etc.

As the resulting focal length of 5000 mm. is very long, there is no need of a Barlow lens to increase the focal length and it also possible to use long focus eye-pieces.

For this beautiful O.T.A. it is also available the Feather Touch FTF 2000 focusing system and a motorized focuser.

Happy journey through the Solar System! And beyond, if you can…

Optical scheme Dall Kirkham
Nominal optical aperture 254 mm.
Actual optical aperture 250 mm.
Focal ratio f 20
Effective focal lenght 5000 mm.
Primary mirror focal length f 3 – 750 mm.
Back focus 250 mm.
Thickness of primary glass 30 mm.
Glass of primary and secondary Suprax Schott Germany
Reflective coating type Quartzed aluminum SiO2
Optical surface correction diffraction limited
Stehl ratio 0,96
Average reflection 94%
Primary diaphragmation 4 mm.
Diameter of the secondary 55 mm.
Thickness of the secondary 15 mm.
Secondary mirror focal multiplier factor 6,66x
Actual obstruction 28%
Diameter of the 100% illuminated field 30 mm.
Maximum diameter of the tool/instrument 360 mm.
Internal dimeter of the carbon tube 280 mm.
Maximum length of the tube, without accessories 935 mm.
Maximum weight without accessories kg. 17
Cell holding the primary NortheK StabilobloK
Secondary holder NortheK AxyS
Structure of the whole tube NortheK UnitorK
Swallow-tailed holder and plate Upon request
Outer protection Hard anodization, colour black
Nuts and bolts Stainless steel, Ergal
Standard searcher 8×50 achromatic
Focus Feather Touch FTF 2000 2″
Tool box Included
Maintenance manual Included
Optic cap Included
Primary mirror baffles Upon request
Thermometric probe Upon request
Optics cleaning set Upon request
Carbon joints to add accessories Upon request
Feather Touch MKIT 20 Upon request

The exact optical parameters such as back focus, distance between primary and secondary, dimensions of the glasses, are confirmed exactly in the optical certificate provided with each optic and/or instrument.

Product code: OTA 250 DK – OTA 250 DKN Sale unit: piece


Product traceability and security codes: every NortheK O.T.A.  has its identification number stamped in a specific and fixed position and it contains all production data and the relevant code of the customer who bought it. This number guarantees the product is Made in Italy, its traceability and the origin of the source project. The stamp is laser marked and cripted.