Planewave Europe

CDK17 Astrograph f/6.8 with Fused Silica Optics

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PlaneWave CDK17 Astrograph f/6.8

The PlaneWave Instruments CDK17 is a 17 inch (0.43 m) f/6.8 Corrected Dall-Kirkham Astrograph telescope. The CDK17 covers a 70 mm field of view without any field curvature, off-axis coma, or astigmatism. The instrument weight is 94 lbs (43 kg) and comes standard with a back plate retaining ring ready to accept the focuser of your choice.

The abbreviation CDK stands for the optical system of the PlaneWave astrographs - a Dall Kirkham Cassegrain with a optical correction unit. More about the Optical Design (CDK)

CDK17" Astrograph, 17 inch with Borosilicate Optics or Fused Silica Optics
modified to Dall-Kirkham, with fully corrected image field
focal length 2.939 mm (f/8)
Delta T Ready, 3,5" Hedrick Focuser and EFA Kit separately available
Requires a crating #1323517. The crating will be charged extra

Fused Silica

Fused Silica is a synthetic amorphous silica glass of the highest purity and one of the most transparent glasses made. The optical and thermal properties of fused silica are superior to other types of glass due to its purity. Its transmission and homogeneity exceed those of crystalline quartz without the problems of temperature instability inherent in the crystalline form. Fused Silica has a coefficient of thermal expansion six times lower than Borosilicate (Pyrex) glass, which means that as fused silica cools down, it preserves its shape to a high degree of accuracy. This translates into consistent optical performance and unchanging focus over temperature changes. With its high melting temperature ()~ 1.600 degree Celsius), a very low coefficient of thermal expansion and resistance to thermal shock, fused silica is the material of choice for professional observatories as well as various scientific applications.

Spot diagram

The graphic on the right shows the vignetting and spot diagrams for the CDK 17 Widefield Astrographer depending on the large CCD chips KAF 6303, KAF 11000 and KAF 09000 for the three wavelengths 730, 585 and 430 Nanometer.

The diameter of a star at the edge of the flat field corresponds to the pixel size of current large-format CCD chips and the imaging quality of the optics is limited only by the seeing conditions and the quality of the tracking. The large field of view of 70mm diameter offers enough tolerance for CCD cameras with ever larger chips - also for amateur astronomy.

Scope of delivery

includes 8" dovetail
Heating elements for dew prevention – The heating pads on the primary and secondary mirror require the #1329110 Delta-T controller and sold separately
OTA cover – To protect the primary mirror and inside of the optical tube
Flash Drive – Contains software and instructions for collimation and spacing the primary to the secondary mirror
Wrench set (5812A35) – Standard hex wrenches (European orders only)
Soft cover for secondary mirror
12v AC adapter

Shipping: dimensions and weight

Width

30 inch (762 mm)

Height

37 inch (940 mm)

Length

58 inch (1,473 mm)

Weight

225 lbs (102.1 kg)

The information is only a rough estimate! The actual shipping dimensions and weight may differ.

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