12.5″ Imaging Harmer Wynne (iHW)

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Telescope Name: 12.5″ Imaging Harmer Wynne (iHW)

Telescope Price: $15,375

Item #: iHW125

The AG Optical Systems 12.5″ F3.9 Imaging Harmer Wynne (iHW) astrograph is a premium quality ultra wide field imaging instrument featuring a 50mm flat field free from astigmatism and coma. The outstanding optical performance of the 12.5″ iHW is made possible through the use of a three element, permanently aligned field corrector combined with a low expansion substrate F3.9 optical system.   Wide field images up to 2.3 degrees are captured with high-contrast details and sharp stars across the entire field of view.






Objects that are too large to be captured using narrow field systems can now be imaged on a single CCD without the need to resort to complex and time consuming mosaics or very expensive large chip CCD cameras.

The Imaging Harmer Wynne carbon fiber truss optical tube assembly makes 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 substrate optics. Three cooling fans speed the cooling of the primary mirror while primary and secondary mirror anti-dew heaters can be automatically controlled by the optional Thermal Control System (TCS).

The 12.5″ iHW provides exceptional thermal stability. Low expansion optics ensure the figure and focus stability of the 12.5″ iHW as the ambient temperature changes over the course of an imaging session. When combined with the rigid, thermally stable carbon fiber truss tube assembly of the 12.5″ iWH you can expect to spend less time focusing and more time collecting data.

The optional state-of-the-art Optec Gemini rotating focuser is a perfect match to the 12.5″ iHW providing precision focusing capability, image train rotation, and heavy payload capability. The electronic control system included with the Gemini focuser allows the Gemini to be controlled by any ASCOM compatible autofocus software program.





Optical Tube Assembly

  • Compact and portable 42 lbs. carbon fiber tube assembly
  • Low expansion substrate F3.9 optical system
  • Large 50mm corrected imaged circle (2.3 degrees)
  • Cooling fans and optional Thermal Control System
  • Dust covers
  • All CNC-machined components, stainless steel fasteners

Optical System

  • 12.5″ F3.9 Harmer Wynne optical system with integral field corrector
  • 7.15″ secondary obstruction (57% linear obstruction)
  • Performance: 5 micron RMS 13mm off-axis, 8 microns 35mm off-axis
  • 4.95″ of back focus with Gemini focuser installed
  • 96% enhanced aluminum coatings
  • Three-element permanently-aligned field corrector with broadband anti-reflection coating on all surfaces (<.5% reflectivity from 400 to 700 nm)



Truss shroud

Truss Shroud

Heavy Lycra shroud to block stray light, mitigate dust intrusion

Price: $135

Item #: FA12SHROUD


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: $235

Item #: FA12PIGGY


  • 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