Orion Optics Dall-Kirkham ODK12 optical tube

For users who prefer a catadioptric telescope that is exceptional for both visual and photographic observation, ORION OPTICS UK has recently introduced its optimized Dall-Kirkham series, called ODK.

The entire model range is based on a focal ratio of F6.8, fast enough for both visual and photographic deep sky use, yet focal enough for high resolution planetary work in both visual and CCD applications.

The tube is constructed with a reinforced carbon fiber design. A very strong and rigid structure to avoid bending and with a low expansion/dilation coefficient to ensure that the focal plane will not be altered when taking long exposures.

Being an open and very short tube, the tube acclimatization times are quite fast. To help the telescope reach thermal equilibrium sooner, each model comes equipped with three fans, all of which are placed at the rear of the primary mirror.

Precision focusing is also easy to achieve on the ORION OPTICS UK ODK telescopes thanks to the recently introduced 3" Crayford focuser with a 10:1 double speed reduction system that is supplied as standard (an electronic focuser with variable focusing speed is available as an additional accessory upon request).

The mirrors on ORION OPTICS UK OKD telescopes are hand finished for excellent performance. Each mirror has been checked several times throughout the production process, both individually and as part of the entire optical assembly. This ensures that the entire optical group of the system is finished to give the best possible image.

To achieve the wide flat field of view for visual and photographic use, ORION OPTICS UK ODK telescopes have designed and integrated into the optical system a group of corrector lenses to ensure both color correction, coma and spherical aberration is optimized to achieve a near perfect total field of view.

On the other hand, the suitable backfocus allows the use with almost 100% of the CCD cameras available on the market today, by using the corresponding accessories.

Multi-layer anti-reflection coatings are applied to all surfaces to ensure brighter images. To ensure collimation stability, the spider and secondary mirror holder are designed as a single piece by CNC machining. ORION OPTICS UK' s unique collimation system allows perfect collimation of the secondary mirror to be achieved quickly and reliably. In addition, for maximum collimation accuracy, the primary mirror can also be collimated.

Computer modeling optimized designs ensure that both mirrors and corrective lenses can be easily collimated and kept firmly aligned. All ORION OPTICS UK ODKs are supplied with a dovetail (although rings are available instead of the typical dovetail if preferred).

The carbon fiber tubes are fitted with a 3" focuser and two plate holders to which dovetails (supplied) or other accessories can be attached.

The OC2 focusers supplied with the ODK tubes are designed to hold up to a maximum weight of 4Kg.

Technical Specifications:

Primary diameter: 300mm
Focal length: 2040mm
Focal ratio: F6.8
Tube weight: 19Kg
Tube diameter: 350mm
Tube length: 615mm
Backfocus (BFD): 209mm
Material used: Carbon fiber reinforced
Secondary diameter: 120mm
Primary cell: cNC machined aluminum cell
Focuser: 3" Crayford with 10:1 double speed reduction
Corrector Design: 3 Multi-Treated Lenses
Flat field size: >52mm
Spot size on optical axis: 1.8µ
Spot size at end of field: 5.6µ
Mirror/tube cooling: 3 controllable fans
Mounting method: Aluminum dovetail designed under numerical control and with brackets