An alt/az mount is inherently more stable than an equatorial mount as there is no cantilevered mass, nor are there any large counterweight protruding that are very dangerous in a public observatory. The mass it takes to make a rigid Alt/Az mount is substantially leading to cost savings. There is no dealing with balance changes as you cross the meridian or meridian flips that German Equatorial Mounts have to deal with. You can image from horizon to horizon continuously if desired. Alt/Az is more intuitive to use and there is no polar alignment needed.
Plane Wave Instruments 0.7m CDK Telescope System
Besides, it is the way the big boys do it.
Benefits of Nasmyth Focus:
The Nasmyth Focus is along the altitude axis so there are virtually no balancing issue as you change out equipment. In addition the CDK700 comes standard with a field rotator / field framer.
Direct Drive Motors and Encoders:
Direct Drive motors means that there are no gears which cause backlash and periodic error. With the high resolution encoders providing the feedback for the direct drive motors, not only will the telescope track without periodic error or have any backlash at all, but the mount will be able to counter against wind gusts. The direct drive motors can move the telescope at incredible speeds for tracking satellites or just to minimize target acquisition time.
CDK Optical Design:
Our design produces a flat, coma free and astigmatic free field of view. Since the secondary mirror is spherical, centering is very forgiving (which means it is easy to get the telescope optics aligned for optimum performance, this is not the case for most high-end astrographs) The end result at the image plane of the CDK design is no off-axis coma, no off-axis astigmatism, and a perfectly flat field, all the way out to the edge of a 50mm image circle. All this means, the stars will be pinpoints from the center of the field of view out to the corner of the field of view.
Plane Wave Instruments 0.7m CDK Telescope System Features
- Pinpoint stars out to a 70mm image circle
- Dual Nasmyth focus
- Direct drive motors on each axis
- Hi Res Encoders on each axis
- Zero backlash
- Zero periodic error
- PointXP Mount Modeling Software
- Field de-rotator / field framing
- Stiff, smooth, quiet and extremely fast drive system
Plane Wave Instruments Product Number: CDK700
Optical Design Corrected Dall-Kirkham (CDK) Aperture 700 mm (27.56 inch) Focal Length 4638 mm Focal ratio f/6.6 Central Obstruction 42% of the Primary Mirror Diameter Back Focus 305 mm (12 inch) from Mounting Surface Focus Position Nasmyth Focus Usable Field of View 70 mm (0.86 degrees) Fully Baffled Field 60 mm Image Scale 22 microns per arcsecond Optical Performance 1.8 micron RMS spots [25mm on-axis] (400 to 900nm)
4.4 micron RMS spots [21mm off-axis] (400 to 900nm)
6.8 micron RMS spots [35mm off-axis] (400 to 900nm)
Fork Assembly Single piece U shaped fork arm assembly for maximum stiffness Azimuth Bearing 20 inch diameter thrust bearing Altitude Bearing 2 x 8.5 inch OD ball bearings Optical Tube Dual truss structure with Nasmyth focus
Motor Control Sideral Technology 3 phase 24 V AC brushless motor controller. Telescope mount modeling software included optimal pointing and tracking accuracy. Azimuth Motor Direct Drive 3 Phase Axial-Flux Torque Motor Altitude Motor Direct Drive 3 Phase Axial-Flux Torque Motor Encoder - Azimuth and Altitude 10 inch disk built into the azimuth and altitude axes with stainless steel encoder tape on the circumference with reader yields 16 million counts per revolution of the telescope. This translates to about 0.08 arcsecond resolution. Motor Torque Approximately 35 ft-lbs Drive Electronics Capable of controlling up to 4 high speed encoders, limit switch inputs, homing switch inputs, controls two additional motors for accessories, two brake outputs and 16 digital and 2 analog inputs SiTech Telescope Control Software Incorporates PointXP mount modeling software by Dave Rowe and SiTech’s control software. All ASCOM compatible.
Point XP Modeling Software Telescope mount modeling software included for optimal pointing and tracking accuracy. SiTech Control Electronics Controls the motion of the telescope, the field de-rotator and the focuser Focuser Large aperture, heavy-duty focuser can handle large payloads and will not add vignetting. The focuser is motor controlled and is ASCOM compatible Field De-Rotator / Image Framer Built in field de-rotator and image framer Cooling Fans and Temp Sensors Multiple cooling fans and multiple temperature sensors for monitoring and equilibrating the primary mirror
Pointing Accuracy 10 arcsecond RMS with PointXP Model Pointing Precision 2 arcsecond Tracking Accuracy 1 arcsecond error over 3 minute period System Natural Frequency 10 Hz or greater Field De-Rotator Accuracy 3 microns of peak to peak error at 35mm off-axis over 1 hour of tracking (18 arc sec)
Primary Mirror Blank Spec
Radius of Curvature 4115mm Optical Diameter 700 mm (27.56 inch) Outer Diameter 714.38 mm (28.125 inch) Core Diameter 203mm (8 inch) Material Pyrex or Borosilicate Precision Annealed Edge Thickness 2.25 inch Cell 18 point
Secondary Mirror Blank Spec
Radius of curvature 2961 mm Thickness 38.1 mm Optical Diameter 270 mm Outer Diameter 280 mm Cell 3 point RTV
Tertiary Mirror Blank Spec
Optical Major Dia 152.4 mm Thickness 25 mm
NOTE: All specifications and dimensions are subject to change. And we do expect small changes in many of the specifications.
- Additional Information
SKU PI-CDK700 Manufacturer PlaneWave Telescope Series Planewave CDK Optical Design Corrected Dall-Kirkham Mount Type Alt-Azimuth - Motorized Warranty 2 Year Warranty Telescope Aperture 27.56" Telescope Focal Length 4638mm Telescope Focal Ratio f/6.6 Optical Coatings Fully Multi-Coated Tube Color or Finish Matte Black Optical Tube Outer Diameter Not supplied by manufacturer Length of Optical Tube Not supplied by manufacturer Optical Tube Weight Not supplied by manufacturer Limiting Stellar Magnitude 16 Highest Useful Magnification Not supplied by manufacturer OTA Mount Type Dual Fork Arms Finder Included None Power Adapter Included AC Wall Adapter
- Included Items
- Plane Wave Instruments 0.7m CDK Telescope System:
- Optical Tube
- Fork Assembly
- Nasmyth Focus
- Azimuth and Altitude Encoders
- Field Rotator / Field Framer
- Point XP Modeling Software
- SiTech Control Electronics
- Cooling Fans and Temp Sensors
- SiTech Telescope Control Software
- Drive Electronics
- Azimuth Motor
- Altitude Motor
- Motor Control
- Questions & Answers
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