The ODK12 and all the range is based on a focal ratio of f6.8, fast enough for some superb deep sky photo-visual use and, still have enough focal length for high resolution planetary work both visual and CCD applications.
As with all the ODK models, the ODK12 is fitted as standard with our ACU-3S, 3” focuser to enable a strong focusing platform for a wide range of cameras. Being both a photographic and visual telescope you are assured of some spectacular views of the planets, the Moon and even faint nebulas and galaxies.
The ODK12 produces very tight, well defined images. The field size is usable to over 52mm ensuring you have the choice of some higher power imaging and views on axis for the planets and moon etc but also, the capability to present to your camera some amazing fields of Deep Sky objects, particularly those requiring a higher degree of magnification.
The full range is based on a focal ratio of f6.8, fast enough for some superb deep sky photo-visual use and, still have enough focal length for high resolution planetary work both visual and CCD applications.
The tube is constructed from Carbon Fibre sandwich design. Very, very strong to avoid flexing and, zero expansion to ensure the focal plane does not change over long photographic exposures. Being an open tube design and very short, cool down times are remarkably fast.
To assist cool down of the telescope, each model is fitted with three fans, all positioned behind the primary mirror.
Customers with heavier than normal (4kg+) CCD equipment can add features to the ODK tube to enhance stability.
Below is an image of the ODK lightpath:
To produce the photo-visual wide, flat field of the ODK range, we have designed and fitted integrally, a corrector lens system. which ensure both colour correction, coma and spherical aberration are optimised to achieve almost a perfect photographic and visual field. Adequate back focus allows all modern CCD cameras to be used with auxiliary equipment. Multi layer anti reflection coatings are applied to all lens surfaces to maintain brighter images.
CNC machined mono construction secondary spider and trim ensures stability in collimation. Our unique collimation adjustment system enables perfect collimation of the secondary mirror to be achieved, quickly and reliably.
About the Focuser:
Exact focusing across the ODK range is achieved with our own Precision ACU-3S 3” Crayford Focuser featuring a 10:1 reduction drive included as standard - focuser pictured below. Good images need good optics, all fitted in reliable, stable and precise engineering.
Our ODK series of Optimised Dall Kirkhams is supported by a precision 3” focuser of short draw tube length. The top of the draw tube is threaded to accept many accessories, adaptors and spacing componenets. Silky smooth, incredible strength and attractive looks give you all the reliability and confidence in the ACU-3S you are ever likely to need. 3” internal threaded draw tube (76.2mm) enables wide fields to be achieved with vignetting not being a problem. Ultra accurate 10:1 slow motion control with a smooth, effortless motion which has got to be tried to be believed. Carrying capacity way beyond the requirements of all but the heaviest cameras.
The focuser is connected to our telescopes by means of a very accurate machined female dovetail which is held onto a male equivalent on the telescope tube or cell with stainless steel grub screws. The beauty of this arrangement is that these screws and dovetail coupling allow you to rotate the focuser through 360 degrees rotation. In other words, to put it in exactly the rotational position you want for the attached equipment fitted, CCD, filter wheels, guiders etc. It just makes it so easy to set things up perfectly to meet your needs.
About the optics:
All our ODK primary mirrors are made from Schott Borosilicate Low Expansion Suprax glass (virtually identical to Pyrex), as are all our primary mirrors on all ranges of telescopes. The mirrors are all produced to exacting standards to an F4 paraboloid configuration. How exact are they? Well, we don’t release one to our coating department unless it achieves a surface accuracy of 1/6 wave or better. How do we know when we have achieved that very high degree of accuracy?
We use one of the worlds most exacting measuring devices, a Zygo Laser Interferometer, it can measure optical distances which are smaller than 2,000, yes, 2,000 times smaller than the thickness of a human hair.
Without a Zygo or similarly accurate and reliable measuring instrument, it is impossible to give accurate measurements of an optics’ or telescope’s performance. Only the best manufacturers in the business of making telescopes use them because they are not suitable for mass produced telescopes, they are slow to use and need highly skilled technicians to operate them, it just does not lend itself to anything other than the highest quality, hand figured optics, definitely not mass produced optics to a tight budget.
Primary mirrors are Hilux coated for the highest possible aluminium protected reflective surfaces available.
Optional electronic focus system is available for the ASU Focuser on these telescopes, please contact us for more information.
Optional matching carbon dew shields and dew shields with heaters are also available.
Please note: If customers require these fitting to either ODK or AG telescopes we, by necessity, mould them internally to avoid movement and to maintain regular conduction and convection. These orders are then considered a custom order and cannot receive any refund if the order is cancelled for any reason.