The PlaneWave 20" CDK (Corrected Dall-Kirkham) Optical Design is an innovative solution for unsurpassed astroimaging quality at an affordable price. The CDK telescope design provides excellent imaging with large format CCD cameras while remaining superb for visual use. The CDK design far exceeds the off-axis performance of most commercial telescope designs including the Ritchey-Chrétien design. This no-compromise design is unique in making the optical alignment forgiving and collimation very easy. This guarantees the user the best possible performance from the telescope. The end result at the image plane of the CDK design is no off-axis coma, no off-axis astigmatism, perfectly flat field (no off-axis defocus). The CDK design will give you pinpoint stars from the center to the corner of the field of view. More about our Optical Design
The PlaneWave Instruments CDK20 is a 20 inch (0.51 m) f/6.8 Corrected Dall-Kirkham Astrograph telescope. The CDK20 has a dual carbon-fiber truss design, with 3 cooling fans ejecting air from the back of the telescope. The CDK20 covers a 52 mm field of view without any field curvature, off-axis coma, or astigmatism. The instrument weight is 140 lbs (64 kg) and comes standard with a back plate retaining ring ready to accept the focuser of your choice.
All CDK20 telescopes come with Fused Silica primary and secondary mirrors
Features:
| Carbon Fiber Truss Design | Minimizes thermal expansion which causes focus shift with changes in temperature |  |
| Dovetail expansion joint | Allows for the difference in thermal expansion between carbon fiber and aluminum. The expansion joint allows the aluminum dovetail expand and contract without stressing the carbon fiber lower truss |  |
| Cooling Fans | Three cooling fan blow out of the optical tube pulling air though the telescope and pass the primary mirror. This helps the telescope to reach thermal equilibrium quickly. The fans are controlled by a computer if the optional Electronic Focus Accessory (EFA Kit) is purchased. |  |
| Delta-T Ready | For added dew prevention, the CDK20 is internally wired with polyimide film heater pads and temperature sensor, ready to be controlled with the optional Delta-T controller. |  |
OPTICAL SYSTEM
| Aperture | 20 inch (508 mm) |
| Focal Length | 3454 mm (135.98 inch) |
| Focal ratio | F/6.8 |
| Central Obstruction | 39% of the Primary Mirror Diameter |
| Back Focus from Racked in Focuser | 5.8 inch (147 mm) |
| Weight | 140 lbs (63.5 kg) |
| OTA Length | 47 inch (1,194 mm) |
| Upper Cage | Carbon Fiber Truss |
| Lower Cage | Carbon Fiber Truss with Carbon Fiber Light Shroud |
SECONDARY MIRROR
| Diameter | 7.5 inch (191mm) |
| Material | Fuses Silica |
| Shape | Spherical |
| Coating | Enhanced Aluminium - 96% |
PRIMARY MIRROR
| Optical Diameter | 20 inch (508 mm) |
| Outer Diameter | 20.5 inch (521 mm) |
| Shape | Prolate Ellipsoid |
| Material | Fused SIlica |
| Coating | Enhanced Aluminium - 96% |
LENS GROUP
| Diameter | 90 mm (3.54 inch) |
| Number of lenses | 2 |
| Coating | Broadband AR Coatings (less than .5% reflected from 400 to 700nm) |
SHIPPING
| Crated Shipping Weight | 291 lbs (132.0 kg) |
| Crate Width | 33 inch (838 mm) |
| Crate Height | 40 inch (1,016 mm) |
| Crate Length | 65 inch (1,651 mm) |
INCLUDED ACCESSORIES
| Ronchi Spacer (200354) | This spacer sits in place of a focuser and is used for setting the primary to secondary spacing. It has an 1 .25” inner diameter and may be used with 1.25” oculars for collimation. |
| Ronchi Ocular | This ocular is a Ronchi screen used for setting the primary to secondary spacing. |
| Primary Mirror Cover | The Primary Mirror Cover protects the primary mirror. |
| Printed Instructions | For Collimation and Spacing |
NOTE: This product has a lengthy leadtime. For more details email: education@bintel.com.au