Kson “Olympus” AS102 ED APO (102mm/1200mm f/12) refractor (FPL51/Lanthanum Doublet)


The Kson Olympus AS102 is a f/12 classic air spaced (“AS”), crown and flint doublet achromat refractor with a 102mm and a generous f/12 (f/15 with aperture cap) focal length.

Designed for the pure pleasure of visual planetary, lunar, double star and some DSO viewing, this extraordinary achromat is one of the longest focal length modern achromats currently made, designed for getting up close and personal with extraordinary contrast and clarity – without the hefty ‘ED’ pricetag.

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*PRE-ORDER SPECIAL* – Bonus 2nd Orthoscopic Eyepiece of your choice!

Kson Olympus AS102 ED APO A 102mm (4 inch) f/12 configuration with some serious tricks, unusual features and inclusions up it’s sleeve.

This range is designed for the pure pleasure of visual planetary, lunar, double star and DSO viewing, this extraordinary long focal length refractor will impress.  It combines a modern optical design with traditional, high quality engineering.

The Olympus range comes in two flavours, as an achromat, and now this one, an APO.

Specifications and Features:

  • FPL51 and Lathanum Doublet (Design and Optical Quality APO)
  • Objective Lens Diameter of 102mm, 1200mm focal length, f/12
  • The primary lens is hand-figured by Kson and features excellent spherical correction and smooth surfaces.
  • Fully multicoated with edge blackened lenses. Every lens cell is factory checked for collimation and artificial star tested for quality assurance.
  • The telescope tube features ray-traced baffles to eliminate stray light and also has the inner surfaces painted matt black for superior contrast.
  • Kson “Built for Life” Design – No plastic bits.  User serviceable collimatable lens cell makes it a real lifetime instrument, with no need to ever return it to factory should it ever slip out of collimation.
  • Additional 2″ draw tube extension allows the scope to be used in a large variety of optical configurations and eyepieces and allows for the use of binoviewers with 110-140mm light path without an optical corrector allowing a substantially wider native view to be enjoyed.
  • Sturdy 2″ CG dual-speed crayford style focuser with compression ring and Kson’s unique tri lock screw system – Accepts 2″ eyepieces, DSLR’s and 2″ Accessories
  • Extra long 330mm fully retractable dew shield (also painted matt black inside) allowing easy mobility and transport and providing dew protection
  • Metal quick release bracket on scope
  • The refractor ships with Kson’s own rube rings and extra long 300mm dovetail bar for additional stability on your mount
  • This includes a bonus Premium Kson Ortho II Volcano 4.5mm (carbon fibre) Eyepiece for your viewing pleasure. 
  • Limiting magnitude 12.74
  • Color: Pearl White, Red Rings


  • 80mm aperture cap to convert  to f/15 and reduce moon glare.
  • Handy Nylon Travel Bag included (140x22x22cm) (valued at $99.95)

At the time of purchase, you may purchase the “Kson Starter Pack L” at ($149.95) which adds the following:

  • Red Adjustable Kson 8×50 reticled finder
  • 10mm 3 Element Kson Eyepiece
  • 25mm 3 Element Kson Eyepiece
  • 1.25″ Mirror Diagonal

For the best visual experience, grab some additional Fujiyama or Kson Abbe Orthos of your choice, or a Baader Zoom Mk IV.

Make sure you add a 2″ Diagonal if you don’t already have one.  The Kson 2″ 99% reflectivity one is recommended.


Use the Kson Olympus with your choice of MountFor visual, we recommend a Saxon EQ3 w/Steel Tripod and pier extension (adequate), a Kson EQ4 with a pier extension (very good, and includes extra long slow motion controls), or  HEQ5 or EQ6 Pro with relevant Pier if your looking at automating. 

What’s this about being especially suitable for binoviewers?

Binoviewers are remarkable devices that look like a binocular, but attach into your telescope, allowing you to use both eyes (stereo) for viewing.  The Kson Olympus was designed from the ground up to be highly compatible with binoviewers.  This means that usually, you will NOT need to use an optical corrector, or barlow to make use of them, allowing improved viewing quality, a greater range of compatible eyepieces, and a wider view that would be otherwise possible.  They provide a stunning experience with this particular telescope.

We recommend the Celestron #93691 Stereo Binocular Viewer, coupled with some lightweight eyepieces to get started with binoviewing.



What’s the difference between the Kson Olympus ED APO and the TS-Optics ED?

Both are highly recommended.  A few differences, the TS-Optics is f/11, the Kson is f/12 – that pushes it even deeper into APO territory.  Both use FPL-51.  Kson specifies that they use Lanthanum as part of the 2nd element, TS-Optics does not specify (“additional special glass”).  The Ts-Optics ED has a shorter (1.5x) dew shield, Kson’s one (3x) is designed for extended observing*.  The Kson features a handle, the TS-optics does not. The TS-Optics has a weight of 4.6kg, Kson’s is lighter (more details to come).  The TS-Optics comes with a 2″ to 1.25″ adaptor, dust caps, finder shoe, CNC tube rings and a dovetail bar.  Kson includes a 2″ to 1.25″ adaptor, dust caps, finder shoe, CNC tube rings and a dovetail bar plus a handy nylon bag, a 1.25″ diagonal and a ortho eyepiece.  Final configuration may include a 80mm aperture cap to reduce glare and increase f/ratio to f/15 for particularly bright targets (Lunar / Jupiter).  Aesthetics aside, the Kson is a single piece, the TS-Optics tube unscrews and is a two-piece system, while Kson uses a 2″ extension tube when extra focal length is needed.

* The widely quoted 1.5x of diameter is not actually what is recommended – rather a minimum to stop stray light and have some effect on dew. Sidgwick recommends 2.5 to 3x the diameter, Kson is the only manufacturer to meet that standard making it able to perform with less dew impairment even without dew straps.

What’s the difference between the Kson Olympus ED APO and the TS-Optics SD?

The SD uses FPL53 (instead of FPL51) and “an additional special glass”, but is otherwise identical to compare with the TS-Optics ED.

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Additional information

Weight 12 kg
Dimensions 120 × 40 × 40 cm


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