20″ Imaging Dall Kirkham Quartz

FA telescopes FA telescopes

Telescope Name: 20″ Imaging Dall Kirkham

Telescope Price: $33,295 with quartz optics

Item #: 20iDK

The AG Optical Systems .5 meter (20 inch) F6.7 Imaging Dall Kirkham (iDK) telescope is an observatory-class imaging instrument featuring an 70mm flat field imaging circle free from coma, astigmatism, and field curvature. The outstanding optical performance of the 20″ iDK is made possible through the convergence of careful design, state-of-the-art manufacturing, and precise assembly. Wide field images are captured with high-contrast details and sharp stars across the entire field of view.

The AG Optical Systems 20″ iDK F6.7 optical system provides exceptional thermal stability. Optical grade fused quartz optics ensure the figure and focus stability of the 20″ iDK as the temperature changes over the course of an imaging session. When combined with the rigid, thermally stable carbon fiber truss tube assembly of the 20″ iDK you can expect to spend less time focusing and more time collecting data.

AG Optical Systems iDK series carbon fiber truss optical tube assemblies make extensive use of carbon fiber composite materials, CNC-machined components, and precision collimation adjustments to provide a rigid and thermally stable platform for the low expansion optics. Three cooling fans speed the cooling of the primary mirror while primary and secondary mirror heaters can be automatically controlled by the optional Thermal Control System (TCS).

The optional, robust, digital Optec Gemini rotating focuser or Optec TCF-S3i focuser is ASCOM-compatible is capable of precision focusing and rotation while carrying heavy CCD imaging trains.

 

 

Optical Tube Assembly

  • 140 lbs. carbon fiber tube assembly
  • Tube length: 47 inches
  • 20″ (.5m) optical grade fused quartz F6.7 optical system
  • 70mm corrected imaged circle. 1.2 degrees
  • Cooling fans and optional Thermal Control System
  • Dust covers
  • All CNC components, all stainless steel fasteners

Optical System

  • 20″ F6.7 corrected optical system with integral field corrector correcting coma, astigmatism, and field curvature
  • 3403 mm focal length
  • 9.6″ secondary obstruction (48% linear obstruction)
  • Performance: 3.2 micron RMS 15mm off-axis, 8 micron RMS 35mm off-axis
  • 6.75″ of back focus from Optec Gemini focuser (assumes 1″ extension tube between backplate and Gemini focuser)
  • 96% enhanced aluminum coatings
  • 89mm diameter two-element permanently-aligned field corrector with broadband anti-reflection coating on all surfaces (<.5% reflectivity from 400 to 700 nm)
  • 5.95″ of back focus with Optec TCF-S3i focuser installed
  • 10.25″ of back focus from focuser base

 

 

Truss shroud

Truss Shroud

Heavy Lycra shroud to block stray light, mitigate dust intrusion

Price: $225
Item #: FA20SHROUD

 

optec gemini 3.75

Optec Gemini 3.75″ Rotating Focuser

Low profile (2.5″), rotating digital focuser with 20 lbs payload capacity, temperature compensation feature

Price: $3495
Item #: GEMINI

thermal control system

Thermal Control System

Computer-based automated control of primary mirror cooling, primary and secondary mirror anti-dew control

Price: $995
Item #: TCS

 

Piggyback Dovetail Plate

CNC-machine 6061 aluminum Losmandy “D” profile piggyback dovetail plate

Price: $385
Item #: FA20PIGGY

Optec TCF-S3i 3″ Digital Focuser

Robust, digital 3″ focuser with temperature compensation

Price: $1495

Item: TCFS31

 

 

  • Carbon fiber optical truss tube assembly
  • Losmandy “D” mount dovetail
  • Primary and secondary dust covers
  • Primary mirror cooling fans with power cable
  • Low expansion substrate optics with enhanced aluminum coatings
  • All stainless steel fasteners and springs
  • Backplate carrying handles

20″ Imaging Dall Kirkham Spot Diagram

  • .425 through .7 micron wavelength (LRGB)
  • 10 micron pixel
  • 70mm image circle (on-axis to 35mm off-axis)