PlaneWave CDK20 f/7.77 Lens Group
PlaneWave
CDK20 F/7.77 Lens Group (Converts CDK20 F/6.8 model to F/7.77) is an optical tube for general deep-sky imaging and visual observing.
Best Current Offer
Specifications
Optics
- Optical design
- Corrected Dall-Kirkham astrograph
- Aperture
- 508 mm (20 in)
- Focal length
- to 3951 mm, which is an additional 497 mm of
- Focal ratio
- f/7.77
Imaging
- Image circle
- 70 mm corrected field
- Full-frame coverage
- Yes
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 F/7.77 Lens Group (Converts CDK20 F/6.8 model to 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 | $1,600.00 | Out of stock Updated 8/5/2026 | View Offer - $1,600.00 |
Price History
Chronological retailer pricing with out-of-stock points shown at reduced opacity.