Planewave are American manufacturers of Modified Dall Kirkham Cassegrain Instruments.
These instruments are designed and made to the highest standards with the advanced astro imager very much in mind.
The CDK [Corrected Dall-Kirkham] telescope is based on a new optical design developed by Dave Rowe. The goal of the design is to make an affordable astrographic telescope with a large enough imaging plane to take advantage of the large format CCD cameras of today. Most telescope images degrade as you move off-axis from either coma, off-axis astigmatism, or field curvature. The CDK design suffers from none of these problems. The CDK is coma free, has no off-axis astigmatism, and has a flat field. The design is a simple and elegant solution to the problems posed above. The CDK consists of three components: an ellipsoidal primary mirror, a spherical secondary mirror and a lens group. All these components are optimized to work in concert in order to create superb pinpoint stars across the entire 52mm image plane.
To read more about the Planewave CDK design click here
The PlaneWave Instruments CDK12.5 is a 12.5 inch (0.32 m) f/8 Corrected Dall-Kirkham Astrograph telescope. The telescope has a closed carbon fiber tube, with 3 cooling fans ejecting air from the back of the telescope. The CDK12.5 covers a 52 mm field of view without any field curvature, off-axis coma, or astigmatism. The instrument weight is 46 lbs and comes standard with the large capacity 2.75 inch Hedrick focuser.
The 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.
Vignetting and spot size plots
Spot and diffraction diagrams - click here
Overall Dimensions PDF
Aperture 12.5 inch (318 mm) Focal Length 2541 mm (100.04 inch) Focal Ratio f/8 Central Obstruction 42% of the Primary Mirror Diameter Back Focus from Mounting Surface 10.445 inch (265 mm) Back Focus from Racked in Focuser 7.2 inch (183 mm) Weight (includes manual-focuser and dovetail) 46 lbs (20.9 kg) Weight (includes electronic-focuser and dovetail) 48.5 lbs (22.0 kg) OTA Length 31 inch (787 mm) Optical Tube Carbon Fiber Optical Performance Vignetting and Spot Size Plots Spot and Diffraction Diagrams Overall Dimensions Overall Dimensions (PDF)
PRIMARY MIRROR Diameter 13 inch (330 mm) Aperture 12.5 inch (318 mm) Focal Ratio f/3 Mounting Laser Collimated and Permanently Fixed Material Precision Annealed Pyrex Shape Prolate Ellipsoid Coating Enhanced Aluminum - 96%
SECONDARY MIRROR Diameter 4.65 inch (118 mm) Material Precision Annealed Pyrex Shape Spherical Coating Enhanced Aluminum - 96%
LENS GROUP Diameter 70 mm (2.76 inch) Number of lenses 2 Coating Broadband AR Coatings (less than .5% reflected from 400 to 700nm)
STANDARD FEATURES Carbon Fiber Tube 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 2.75 inch Hedrick Focuser Heavy duty no-slip focuser. The focus tube runs on 5 bearings and is driven by a leadscrew so there is no chance of slipping. It accepts an optional dial indicator and PlaneWave’s EFA Kit to control many electronic accessories. The draw tube travel is 1.3 inch. Image 1 Image 2 Cooling Fans Three fans blow out of the optical tube pulling air though the telescope and by the primary mirror. This helps the telescope to reach thermal equilibrium quickly. The fans are controlled by a switch on the optical tube or can be conrolled by a computer if the optional Electronic Focus Accessory (EFA Kit) is purchased.
SHIPPING Crated Shipping Weight 163 lbs (73.9 kg) Crate Width 23 inch (584 mm) Crate Height 31 inch (787 mm) Crate Length 41 inch (1,041 mm)
INCLUDED ACCESSORIES 2.75" to 2" Adapter (125355) Adap ts the 2.75" inner diameter of the focuser to a standard 2" inner diameter. This adapter is necessary when setting the primary to secondary spacing. The 125399 Visual 2.75" to 2" adapter is an optional accessory that is designed to space a 2" diagonal for visual use. Ronchi Spacer (200354) This spacer is used for setting the primary to secondary spacing. It has an 1-1/4 inner diameter and may be used with 1-1/4 oculars for collimation. Ronchi Ocular This ocular is a Ronchi screen used for setting the primary to secondary spacing. OTA Cover The OTA cover is for closing the front of the tube to protect the primary mirror and the inside of the optical tube. Printed Instructions For Collimation and Spacing Wrench Set (5812A35) English Hex Wrenches
The PlaneWave Instruments CDK17 is a 17 inch (0.43 m) f/6.8 Corrected Dall-Kirkham Astrograph telescope. The CDK17 has a dual carbon-fiber truss design, with 3 cooling fans ejecting air from the back of the telescope. The CDK24 covers a 52 mm field of view without any field curvature, off-axis coma, or astigmatism. The instrument weight is 94 lbs (43 kg) and comes standard with the large capacity 3.5" Hedrick focuser.
Aperture 17 inch (432 mm) Focal Length 2939 mm (115.71 inch) Focal Ratio f/6.8 Central Obstruction 39% of the Primary Mirror Diameter Back Focus from Mounting Surface 8.8 inch (224 mm) Back Focus from Racked in Focuser 5.8 inch (147 mm) Weight 94 lbs (42.6 kg) OTA Length 37 inch (940 mm) Upper Cage Carbon Fiber Truss Lower Cage Carbon Fiber Truss with Carbon Fiber Light Shroud Optical Performance 6.5 micron rms at 21mm and 9.6 micron at 26mm off-axis Vignetting and Spot Size Plots Spot and Diffraction Diagrams Overall Dimensions Overall Dimensions (PDF)
PRIMARY MIRROR Diameter 17.5 inch (445 mm) Aperture 17 inch (432 mm) Focal Ratio f/2.6 Mounting Laser Collimated and Permanently Fixed Material Precision Annealed Pyrex Shape Prolate Ellipsoid Coating Enhanced Aluminum - 96%
SECONDARY MIRROR Diameter 6.25 inch (159 mm) Material Precision Annealed Pyrex Shape Spherical Coating Enhanced Aluminum - 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)
STANDARD FEATURES Carbon Fiber Truss Design Minimizes thermal expansion which causes focus shift with changes in temperature Carbon Fiber Lower Light Shroud Protects the primary mirror from damage and stray light Dovetail The massive PlaneWave dovetail supports the optical tube to provide rigidity. A matching dovetail clamp is available to install on various mounts. Drawing (PDF) 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 3.5 inch Hedrick Focuser Heavy duty no-slip focuser. The focus tube runs on 5 bearings and is driven by a leadscrew so there is no chance of slipping. It accepts an optional dial indicator and PlaneWave’s EFA Kit to control many electronic accessories. The draw tube travel is 1.3 inch. Image 1 Image 2 Drawing of Flange Drawing of Draw Tube Cooling Fans Three fans blow out of the optical tube pulling air though the telescope and by the primary mirror. This helps the telescope to reach thermal equilibrium quickly. The fans are controlled by a switch on the optical tube or can be conrolled by a computer if the optional Electronic Focus Accessory (EFA Kit) is purchased.
SHIPPING Crated Shipping Weight 225 lbs (102.1 kg) Crate Width 29 inch (737 mm) Crate Height 33 inch (838 mm) Crate Length 45 inch (1,143 mm)
INCLUDED ACCESSORIES 3.5" to 2" Adapter (200349) Adapts the 3.5" inner diameter of the focuser to a standard 2" inner diameter. This adapter is necessary when setting the primary to secondary spacing. The 200399 Visual 3.5" to 2" adapter is an optional accessory that is designed to space a 2" diagonal for visual use. Ronchi Spacer (200354) This spacer is used for setting the primary to secondary spacing. It has an 1-1/4 inner diameter and may be used with 1-1/4 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
Wrench Set (5812A35) English Hex Wrenches
This is a reducer designed specifically for flat field telescopes like the CDK. This reduces the f ratio of the CDK telescope 66%. The CDK12.5 f/8 telescope will be reduced down to f/5.3.
Click here for Reducer Instruction Sheet
This is a reducer designed specifically for flat field telescopes like the CDK. This reduces the f ratio of the CDK telescope 66%. The f/6.8 CDK17 and CDK20 telescopes will be reduced to about f/4.5.
Click here for reducer instruction sheet
Accessories for the CDK 12.5 and 17 Telescopes