PlaneWave CDK20 Astrograph f/7.77 with Fused Silica Optics ( 1323222Q)

PlaneWave CDK20 Astrograph f/7.77 with Fused Silica Optics

Description:
The PlaneWave CDK20 f/7.77 is a high-performance 508 mm Corrected Dall-Kirkham (CDK) astrograph designed to deliver exceptional results for large-format CCD imaging. Its optical design eliminates off-axis coma, astigmatism, and field curvature, producing pinpoint stars across a 52 mm flat field.

Compared to the f/6.8 model, the f/7.77 version offers 1.9" of additional back focus and 497 mm longer focal length. It maintains the simplicity of single-mirror collimation and includes advanced 3D-printed internal baffles for superior stray light control. The optical tube is engineered via finite element analysis (FEA) for rigidity and thermal stability.

The Fused Silica optics ensure unmatched thermal and mechanical stability. This ultra-pure glass type has a thermal expansion coefficient six times lower than Pyrex, offering consistent focus across varying conditions. The carbon fiber truss tube minimizes flexure and temperature-induced focus drift.

Delta-T Ready by design, the CDK20 includes polyimide heater pads and sensors wired internally. Cooling is handled by six fans (three rear, three side) that regulate internal airflow. The fans and heaters can be controlled manually or via PlaneWave Interface 3 (PWI3) software when the optional EFA Kit is installed.

Technical specifications:

Optical design: Corrected Dall-Kirkham (CDK)
Aperture: 20" (508 mm)
Focal length: 3951 mm
F-ratio: f/7.77
Corrected field: 52 mm
Back focus: 10.7" (271.98 mm) from mounting surface
Central obstruction: 39% of primary mirror diameter
Glass type: Fused Silica
Optical length: 47" (1194 mm)
OTA weight: 140 lbs (63.5 kg)
Structure: Carbon fiber truss
Cooling system: 3 rear + 3 side fans
Delta-T Ready: yes (requires controller #1329110)
Mounting: 8" dovetail included
Shipping crate required: reference #1323520 (charged separately)

Included accessories:

• 8" dovetail

• Dew heaters built-in (controller sold separately)

• OTA cover

• Soft secondary mirror cover

• Flash drive with collimation software

• Allen wrench set (EU orders)

• 12V AC adapter