PlaneWave CDK20 f/7.77
PlaneWave
CDK20 Optical Tube Assembly (F/7.77) is an optical tube for general deep-sky imaging and visual observing.
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Specifications
Optics
- Optical design
- Corrected Dall-Kirkham astrograph
- Aperture
- 508 mm (20 in)
- Focal length
- 3951 mm (155.55 inch)
- Focal ratio
- f/7.77
- Dawes limit
- 0.23"
- Lens design
- Enhanced Aluminum – 96%
- Central obstruction
- 39% of the Primary Mirror Diameter
Imaging
- Image circle
- 70 mm corrected field
- Field of view
- 52 mm image circle
- Full-frame coverage
- Yes
- Back focus
- from mounting surface 10.7 inch (271.98 mm)
Mechanical
- Tube length
- 47 inch (1,194 mm)
- Weight
- 140 lb (63.5 kg)
Astrophotography Fit
Best for general deep-sky imaging and visual observing when the mount, camera format, and correction hardware are chosen as one system.
CDK20 Optical Tube Assembly (F/7.77) sits in the telescope slot for general deep-sky imaging and visual observing. The important buying question is whether the optical design, focal length, and mount demands match the targets you actually shoot.
Treat it as a system component rather than a standalone tube: the mount, corrector, camera, and focusing hardware decide how good the final data can be.
Best paired with
- Corrected field flattener or reducer when the design requires one
- Cooled APS-C or smaller astro cameras matched to the image circle
- Autofocus, guide scope or OAG, and a mount with comfortable payload margin
Not recommended for
- Large full-frame sensors unless the corrected field supports them
- Very small travel mounts near their realistic imaging payload limit
- Buyers expecting one telescope to be ideal for every target size
Where To Buy
Some links on this page are affiliate links. Prices and availability are pulled automatically from each retailer and updated daily.
| Retailer | Price | Availability | View Offer |
|---|---|---|---|
| Cloud Break Optics Cloud Break Optics | $39,000.00 | In stock Updated 5/14/2026 | View Offer - $39,000.00 |