The new CDK optical design is the most innovative solution currently available on the market for unparalleled quality in astrophotography at a reasonable price. The goal of the CDK design is to offer a telescope that excels in astrophotography using large format CCD cameras (SBIG STL) and at the same time performs splendidly in visual observation. The CDK design far exceeds the performance of most commercial optical designs, including the famous Ritchey-Chrétien, in imaging the peripheral areas of the field of view. The size of the RMS "spots" in the peripheral zone of the field of view captured by a 35mm chip remains smaller than the pixel size of most amateur CCD cameras available today. This design is unique in making optical alignment an unobtrusive task and collimation an extremely easy operation. This assures the user that he can always get the best possible performance from his equipment. The end result in the focal plane of the CDK design is an image with no coma or astigmatism, neither in the central nor in the peripheral part of the field of view, and a perfect flat field (no field curvature). All this is achieved in a 42mm circular image. Therefore, the stars will be totally point-like objects from the center to the far corner of the field of view. Due to the weight of the CDK20 tube it is recommended to use the GM4000/GM4000HPS mount from the manufacturer 10MICRON or the ASCENSION 200HR from PLANEWAVE INSTRUMENTS (ask for more information). System: Diameter: 20" (510mm) Focal Length: 3,454mm Focal Ratio: f/6.8 Central Obstruction: 39% Weight: 63kg Tube Length: 120cm Primary Mirror: Diameter: 520mm Aperture: 510mm Focal Ratio: f/3 Laser collimated and permanently fixed Material: Precision tempered Pyrex Geometry: Ellipsoidal Enhanced aluminum treatment with 96% reflection Secondary Mirror: Diameter: 190mm Material: Precision tempered Pyrex. Geometry: Spherical Aluminum treatment improved with 96% reflection Lens Group: Diameter: 90mm Number of Elements: 2 Broadband Treatment: anti-reflection treatment (less than 0.5% between 400 and 700nm) Standard Specifications: - "Dual Carbon Fiber Truss" design minimizes thermal expansion resulting in focus variations due to temperature changes. - The carbon fiber structure located at the bottom of the primary mirror envelope protects it from possible interference caused by remanent light. - The expansion joint in the dovetail compensates for the differences in thermal expansion between the carbon fiber and the aluminum. The expansion joint allows the aluminum dovetail to expand and contract without stressing the carbon fiber structure. - The CDK20 dovetail comes with one of the following designs: the first would be with the PlaneWave mass dovetail and the second would be with a dovetail compatible with the 10MICRON or SOFTWARE BISQUE type VP mounts. Both designs use the aforementioned expansion joint. - 3.5" "Hedrick Heavy Duty" focuser. The focuser tube slides on 5 bearings and is moved by a screw mechanism so that there is no possibility of focuser slippage. Accepts as optional items a Dial Indicator and EFA Kit to control various electronic accessories. - Cooling fans: 3 fans blow filtered air over the rear of the primary mirror to help it achieve thermal equilibrium very quickly. The fans are controlled by a switch located on the optical tube or can be controlled from the PC if the optional EFA kit is purchased. Dimensions and Weight of the packing box: Dimensions: 150 X 81 X 92cm Weight: 132 Kg
