CDK20 f/7.7 Optical Tube Assembly
$34,000.00
The CDK20 f/7.77 from PlaneWave Instruments stands as a pinnacle of engineering excellence, tailored for serious astrophotographers and astronomers who demand precision and performance. With its advanced technology and high-quality design, the CDK20 f/7.77 delivers outstanding images for a wide range of advanced observational and scientific applications.
*Price excludes shipping and crating. See our crating and pricing policy for full details.
Key Features Overview
The CDK20 f/7.77 is characterized by its exceptional specifications and features:
- 20-inch (508 mm) aperture
- 3951 mm focal length
- f/7.77 focal ratio
- 269.49 mm back focus from mounting surface
- Perfectly flat field across the entire 52mm image circle
- No off-axis coma or astigmatism
- Rock-solid fused silica mirrors with low thermal expansion
- Lightweight and rigid carbon fiber optical tube assembly
CDK20 f/7.77’s Key Features
Large Aperture and Moderate Focal Ratio
The CDK20 f/7.77 features a 508 mm aperture and a high f/7.77 focal ratio. This configuration provides excellent light-gathering efficiency and image scale, making it ideal for detailed lunar, planetary, and deep-sky imaging.
Advanced Optical Design
The CDK20 f/7.77 has a state-of-the-art Corrected Dall-Kirkham optical system that offers exceptional image clarity. This design eliminates off-axis coma and astigmatism and delivers a perfectly flat field, ensuring that images are crisp and detailed across the entire field of view with minimal post-processing required.
Robust Mechanical Structure
Constructed with a carbon fiber optical tube, the CDK20 f/7.77 is lightweight and sturdy. Its thermal expansion coefficient ensures minimal focus shift with temperature changes, making it suitable for extended observing sessions under diverse environmental conditions.
High-Performance Mirrors and Coatings
Featuring fused silica mirrors, the CDK20 f/7.77 maintains precise optical alignment and surface accuracy, even with temperature fluctuations. Its high-quality coatings maximize light transmission and minimize stray light, optimizing performance for critical observational tasks.
Thermal Management
The CDK20 f/7.77 includes cooling fans and a Delta-T ready system to achieve thermal equilibrium rapidly. These features reduce air turbulence within the tube, minimizing image distortion and maintaining consistent imaging quality.
Integrated Dew Control
The telescope incorporates advanced dew prevention technology with heater pads controlled by PlaneWave’s software. This ensures optical surfaces remain clear of condensation in humid conditions, maintaining clear and consistent imaging performance.
Application-Specific Benefits
Astrophotography
With its precise focal ratio and large image circle, the CDK20 f/7.77 allows astrophotographers to capture detailed and expansive views of the cosmos, providing incredible detail and clarity.
Astronomy Research
The stable and precise imaging capabilities of the CDK20 f/7.77 make it an invaluable tool for academic institutions and observatories engaged in sophisticated astronomical research, including detailed photometric studies and complex deep-sky surveys.
Visual Observations
The CDK20 f/7.77 excels in visual observation, offering bright and crisp views ideal for star parties and serious visual astronomy. The telescope's significant aperture and excellent optical quality provide stunning views of planetary, lunar, and deep-sky objects, making every viewing session a memorable experience.
Space Situational Awareness (SSA) and Space Domain Awareness (SDA)
The CDK20 also lends itself to Space Situational Awareness and Space Domain Awareness applications. Its capability to provide detailed observations can be essential for tracking and monitoring satellites and other space debris, contributing valuable data for space traffic management and safety initiatives.
Specifications
CDK20 f/7.7 Optical Tube Assembly
Aperture | 508 mm (20") |
Focal Length | 3951 mm (156") |
Focal Ratio | f/7.7 |
Central Obstruction | 39% of the Primary Mirror Diameter |
Back Focus from Mounting Surface | 269.24 mm (10.6") |
Weight | 140 lbs (63.5 kg) |
OTA Length | 1194 mm (47") |
Optical Design Performance | 1.5-micron RMS on-axis, 3.8-micron RMS at 12 mm off-axis, 6.0-micron at 21 mm off-axis |
Upper Cage | Carbon fiber truss |
Lower Cage | Carbon fiber truss and light shroud |
Diameter | 90 mm (3.54") |
Coating | Broadband AR Coatings (less than .5% reflected from 400 to 700 nm) |
Optical Diameter | 508 mm (20") |
Diameter | 191 mm (7.5") |
Material | Fused silica (quartz) |
Shape | Spherical |
Coating | Enhanced Aluminum - 96% |
Optical Diameter | 508 mm (20") |
Outer Diameter | 521 mm (20.5") |
Shape | Prolate Ellipsoid |
Material | Fused Silica (quartz) |
Coating | Enhanced Aluminum - 96% |
Included Items | Heating Elements for Dew Prevention - The heating pads on the primary and secondary mirror require the 600195 Delta-T controller sold separately |
OTA Cover - To protect the primary mirror and inside of the optical tube | |
Flashdrive - Contains software and instructions for collimation and spacing the primary to secondary mirror | |
Wrench Set (5812A35) - Standard hex wrenches (European orders only) | |
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Electronic Focus Accessory (EFA) Kit |
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Fabric Light Shroud | This is a spandex fabric light shroud that blocks out stray light and minimizes dust on the primary mirror. Available for the CDK14, CDK17, CDK20, CDK24, and CDK700. | $140.00 – $790.00 | ||
Delta T Heater |
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Telescope Dovetail Saddles | The Keller EZ Saddle (600182) accepts Losmandy D-style dovetail rails such as the CDK12.5, CDK14, and DeltaRho 350. This saddle comes standard with the L-350 mount and can also be attached to the outside arm of any L-series mount for dual-mounted OTA configurations. The PlaneWave Wide Saddle (200919) comes standard with L-500, L-550, and L-600 mounts for securing CDK17, CDK 20, CDK24, and DeltaRho 500 telescopes. | $400.00 | ||
IRF90 – Integrated Rotating Focuser |
| $5,200.00 | ||
Piggyback Dovetail Bars |
Please Note- For CDK17 users:
| $400.00 – $650.00 | ||
Hedrick Focuser |
| $1,150.00 | ||
L-500/L-600 Equatorial Wedge |
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Visual Adapter – CDK20/24 | This 3.5″-2″ Visual Adapter, for the CDK20 and CDK24, slides into the optional 3.5″ Hedrick Focuser.
| $160.00 | ||
Finderscope and Mounting Bracket | The back plate on all of the CDK models has four mounting positions for a finder mounting plate.
| $460.00 | ||
2 inch Mirror Diagonal |
| $394.00 | ||
Mounting Bracket for Finderscopes |
| $50.00 | ||
Reducer 0.66x CDK20 / CDK24 | This reducer is specifically crafted for telescopes with a flat image field, such as CDKs, reducing the aperture ratio to 66% for faster imaging and enhanced optical performance. | $1,400.00 |