PlaneWave CDK20 f/6.8 Optical Tube Assembly | PixelSkiesAstro
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  • PlaneWave CDK20 f/6.8 Optical Tube Assembly | PixelSkiesAstro
  • PlaneWave CDK20 f/6.8 Optical Tube Assembly | PixelSkiesAstro
  • PlaneWave CDK20 f/6.8 Optical Tube Assembly | PixelSkiesAstro
  • PlaneWave CDK20 f/6.8 Optical Tube Assembly | PixelSkiesAstro
  • PlaneWave CDK20 f/6.8 Optical Tube Assembly | PixelSkiesAstro

PlaneWave CDK20 f/6.8 Optical Tube Assembly

€50,700.00
Tax included

PlaneWave CDK20 f/6.8 Optical Tube Assembly The CDK20 f/6.8 is a 508 mm Corrected Dall-Kirkham astrograph with a 3454 mm focal length. Its design has no off-axis coma or astigmatism and a flat field across a 52 mm image circle.

Manufacturer model: PlaneWave CDK20 f/6.8 OTA (200104Q) · Specifications checked against manufacturer data on 2026-11-03

PlaneWave CDK20 f/6.8 Optical Tube Assembly

The CDK20 f/6.8 is a 508 mm Corrected Dall-Kirkham astrograph with a 3454 mm focal length. Its design has no off-axis coma or astigmatism and a flat field across a 52 mm image circle.

Construction

Fused silica mirrors and a carbon fibre truss minimise focus shift with temperature. Cooling fans, a Delta-T-ready system and mirror heater pads keep the optics stable and free of dew.

Optical system

Optical design Corrected Dall-Kirkham
Aperture 508 mm (20")
Focal length 3454 mm
Focal ratio f/6.8
Central obstruction 39% of primary diameter
Image circle 52 mm
Primary mirror 508 mm optical / 521 mm outer, prolate ellipsoid, fused silica, enhanced aluminium 96%
Secondary mirror 191 mm spherical, fused silica, enhanced aluminium 96%
Corrector lenses 90 mm, broadband AR (<0.5% reflection, 400–700 nm)

Mechanical

Back focus from mounting surface 224 mm (8.81")
OTA length 1194 mm (47")
Weight 63.5 kg (140 lb)
Tube Carbon fibre truss

Manufacturer documentation

PlaneWave CDK20 f/6.8 OTA

Compatibility notes

CDK20 f/6.8, not the f/7.7 version (3951 mm) or IRDK20. Optical RMS performance not published on the f/6.8 page.

1323220Q

Data sheet

Aperture (mm)
508
Bf mount (mm)
224
Design
Corrected Dall-Kirkham
Focal length (mm)
3454
Focal ratio
f/6.8
Image circle (mm)
52
Length (mm)
1194
Lenses
90 mm broadband AR
Obstruction
39% diameter
Primary
508/521 mm prolate ellipsoid fused silica, Al 96%
Secondary
191 mm spherical fused silica, Al 96%
Weight (kg)
63.5
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