Loading... Please wait...

Our Newsletter

AG Optical Systems iDK20" Imaging Dall Kirkham (iDK) Astrograph

  • Image 1
In Stock
Calculated at checkout
Bookmark and Share

Product Description

AGO iDK Astrographs

AGO Imaging Dall Kirkham (iDK) astrographs are high resolution instruments with excellent on and off axis performance.  By combining large aperture, medium focal ratio, corrected optics in a lightweight, stiff, and thermally stable carbon fiber tube AGO has created an instrument capable of capturing stunning images of our universe.

  • Optics figured and quality tested as a system
  • Fast F6.7 system designed and baffled to cover 16803 size chip
  • 6" to 8.5" of back focus to support almost any combination of imaging components (dependent upon focuser selected)
  • Excellent coma free, astigmatism free, flat field performance over 70 mm image circle
  • Highly robust, precise Optec TCF-S3i focuser is standard.  Optional FLI Atlas focuser.
  • Outstanding field illumination across big chip cameras.
  • Carbon fiber truss tube engineered to provide rigidity and thermal stability.  Optional AGO Thermal Control System to automatically control fans, primary heater, and secondary heater.
  • Multiple spacer and camera adapter options

Model Specifications

Model iDK12.5  iDK17 iDK20
Aperture 12.5" 17" 20"
Focal ratio 6.7 6.7 6.7
Focal length 83.5" 114" 134"
Back focus 6" with Optec TCF
8.5" with FLI Atlas
6" with Optec TCF
8.5" with FLI Atlas
6" with Optec TCF
8.5" with FLI Atlas
OTA type Truss Truss Truss
Primary mirror  Supremax 33 substrate
Fans (blowing air into OTA)    3 x 60mm fans 3 x 80 mm fans 4 x 80 mm fans
Secondary obstruction 6.7" 8.2" 9"
Focuser (included) Standard: Optec TCF-S3i 3" temperature compensating digital focuser
Optional: FLI Atlas
Corrector 85mm two element,
broadband AR coated
100mm two element broadband AR coated
Mirror Coatings Enhanced
Baffling primary and secondary carbon fiber composite baffles, baffled for 16803 size chip
Dovetail Massive, thermally compensated dovetail plate included

Optical Design

AG Optical Dall Kirkham astrographs provide pinpoint stars (sub 6 micron RMS spot size, 70 mm image circle) over large fields of view at a moderate F6.7 focal ratio.  This exceptional wide field performance is made possible by the use of a two element corrector which reduces coma, field curvature and astigmatism to negligible levels.

Each AGO iDK corrector is permanently aligned and has multilayer broadband AR coatings (<0.5% reflection) on each optical surface.  The corrector provides a 70 mm diameter circle of pinpoint stars capable of covering chips as large as those found in 16803 cameras.

Stray light is effectively controlled through the strategic placement of baffles at the primary and secondary mirrors.  As an added measure, the interior of each AGO iDK is lined with a flocking material that is extremely effective at trapping stray light. 

The combination of an excellent optical design, top quality components, and careful assembly ensure that each AGO iDK astrograph will provide outstanding performance where it counts..... at the chip of your CCD camera.

Optical Testing

AGO is committed to delivering telescopes that consistently offer performance second to none.  To meet this objective each set of iDK optics is tested as a system in autocollimation.  The type of testing is time consuming and expensive but it essentially guarantees that the optics will provide outstanding performance and realize the potential of the excellent design.

Back Focus

AGO has designed our iDK to be CCD imaging platforms capable of the highest performance.  Serious CCD imagers use a wide range of accessories to get that perfect image and finding adequate back focus is always a challenge.  With the availability of image rotators, off axis guiders, adaptive optics and various filterwheels back focus is rapidly consumed.  Each AGO iDK has approximately 11" of useable back focus (as measured from the back plate to the focal plane) which is sufficient for nearly any image train combination. 

A variety of spacers and adapters are available to help you dial in the perfect position for your CCD imaging train.  Please do not hesitate to contact AGO to discuss your specific needs.


AGO has selected the Optec TCF-S3i focuser as standard equipment for our iDK astrograph line.  This focuser is capable of carrying heavy camera loads and is extremely precise offering repeatable, predictable automatic focusing.  Its digital control system allows automatic focusing of stars and perfectly complements an AGO iDK astrograph. With the Optec TCF-S3i in place, approximately 6" of back focus is available to accommodate imaging equipment.

Spacers and Adapters

Spacers Tubes

AG Optical Systems offers spacers in .125", .25", .5", 1", 2", and 4" lengths to help you locate your camera at the proper back focus position.   Spacers connect to each other using screws (provided with each spacer) for a rigid, tilt-free connection.  Please note that the .125" spacer has through holes only and is designed to fine tune back focus for the FLI Atlas option.

Each spacer has a 3" inner diameter and is precisely machined from 6061 aluminum with a black anodized finish.  The interior of each spacer is carefully blackened with a flat black paint to minimize stray light reflections.


Adapters to link spacers to the Optec TCF-S3i or FLI Atlas are available.  Adapters are also available to mount you camera, filter wheel, rotator, or off-axis guider to the focuser or to a spacer. 

What you need to connect your camera to an iDK......

  1. With Optec FCF-S3i focuser (focuser mounted directly to back plate)
    1. Optec TCF-S3i to spacer adapter
    2. Spacer(s)
    3. Spacer to camera, filter wheel, or OAG adapter

What you need to connect your camera to an iDK with the FLI Atlas option.....

  1. With FLI Atlas focuser
    1. Back plate to spacer adapter
    2. Spacer(s)
    3. Spacer to FLI Atlas adapter
    4. FLI Atlas focuser
    5. FLI Atlas to camera, filter wheel, or OAG adapter

Find Similar Products by Category

Add to Wish List

Click the button below to add the AG Optical Systems iDK20" Imaging Dall Kirkham (iDK) Astrograph to your wish list.

You Recently Viewed...