Planewave CDK17 - 17" Corrected Dall-Kirkham Telescope

description - in progress

Planewave CDK17 - 17" Corrected Dall-Kirkham Telescope
Aperture 17 inch (432 mm)
Focal Length 2939 mm (115.71 inch)
Focal Ratio f/6.8
Central Obstruction 39% of the Primary Mirror Diameter
Back Focus from Mounting Surface 8.8 inch (224 mm)
Back Focus from Racked in Focuser 5.8 inch (147 mm)
Weight 94 lbs (42.6 kg)
Upper Cage Carbon Fiber Truss
Lower Cage Carbon Fiber Truss with Carbon Fiber Light Shroud
Optical Performance 14.4mm off-axis: 4 micron RMS spot size; 21mm off-axis: 6.5 micron RMS spot size; 26mm off-axis: 9.6 micron RMS spot size
Overall Dimensions 39.5 inch (1003mm) long X 21.5 inch (546mm) wide X 24.5 inch (622mm) high

Planewave CDK17 - Primary Mirror
Diameter 17.5 inch (445 mm)
Aperture 17 inch (432 mm)
Focal Ratio f/2.6
Mounting Laser Collimated and Permanently Fixed
Material Precision Annealed Pyrex
Shape Prolate Ellipsoid
Coating Enhanced Aluminum - 96%

Planewave CDK17 - Secondary Mirror
Diameter 6.25 inch (159 mm)
Material Precision Annealed Pyrex
Shape Spherical
Coating Enhanced Aluminum - 96%

Planewave CDK17 - Lens Group
Diameter 90 mm (3.54 inch)
Number of Lenses 2
Coating Broadband AR Coatings (less than .5% reflected from 400 to 700nm)

Planewave CDK17 - Standard Features
Design Carbon fiber truss design that minimizes thermal expansion which causes focus shift with changes in temperature
Dovetail The massive PlaneWave dovetail supports the optical tube to provide rigidity. A matching dovetail clamp is available to install on various mounts.
Light Shroud Carbon fiber lower light shroud that protects the primary mirror from damage and stray light
Dovetail Expansion Allows for the difference in thermal expansion between carbon fiber and aluminum without stressing the carbon fiber lower truss.
Hedrick Focuser 3.5 inch Hedrick heavy duty no-slip focuser. The focus tube runs on 5 bearings and is driven by a leadscrew so there is no chance of slipping. It accepts an optional dial indicator and PlaneWave’s EFA Kit to control many electronic accessories. The draw tube travel is 1.3 inch.
Cooling Fans Three fans blow out of the optical tube pulling air though the telescope and by the primary mirror. This helps the telescope to reach thermal equilibrium quickly. The fans are controlled by a switch on the optical tube or can be conrolled by a computer if the optional Electronic Focus Accessory (EFA Kit) is purchased.

Planewave CDK17 - Included Accessories
Focuser Adapter 3.5" to 2" Adapter (200349). Adapts the 3.5" inner diameter of the focuser to a standard 2" inner diameter. This adapter is necessary when setting the primary to secondary spacing. The 200399 Visual 3.5" to 2" adapter is an optional accessory that is designed to space a 2" diagonal for visual use.
Ronchi Spacer (200354) This spacer is used for setting the primary to secondary spacing. It has an 1-1/4 inner diameter and may be used with 1-1/4 oculars for collimation.
Ronchi Ocular This ocular is a Ronchi screen used for setting the primary to secondary spacing.
Primary Mirror Cover The Primary Mirror Cover protects the primary mirror.
Printed Instructions For Collimation and Spacing
12VDC Power Supply (18778) Provides power for the fans

The Planewave website has more information about the Planewave CDK17.

Images with the ASA N12

Bifrost Observatory Index

Bifrost Astronomical Observatory