Astronomy Specialist



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The Sharpstar AL-140PH APO is an apochromatic triplet with a focal ratio of f/6.5 and a focal length of 910mm. The objective lens includes two Extra Low Dispersion glass for a superb chromatic correction.

The large rack and pinion 4" focuser can be rotated 360°and it has a reduction gear of 1:10 for precise focusing. This refractor works at its best when used with the SharpStar 2.5" field flattener for superior performance in astrophotography. The focuser is compatible with the ZWO EAF electronic focuser bracket.


All the lenses are fully multi-coated and the tube is internally flocked to reduce reflections and absorb stray light. The tube is made of aluminium, the rack and pinion focusing mechanism of brass and the mechanical components are engineered to provide the best rigidity, performance and durability.

Every SharpStar telescope is inspected on the optical bench by Testar and guaranteed against defects. To ensure optimal performance, every telescope  undertakes the following tests:

  • Star test in autocollimation by using a Zerodur λ/20 mirror to revel tensioned optics or optical aberrations
  • Collimation test using a GMK collimator
  • Ronchi test to evaluate the overall correction of the lenses.

    Chromatic aberration diagram


    Optical design

    Apochromatic triplet dual ED air spaced

    Objective diameter

    140 mm

    Focal length

    910 mm

    Focal ratio


    Resolving power

    0.86 arc second

    Stellar limiting magnitude


    Max. magnification

    280 x

    Light gathering power

    400 times the human eye

    Mount attachment

    Losmandy style bar


    Rack & pinion dual speed (10:1) 4" diameter

    Camera connection

    M102 x 1 male / M88 x 1 female / M68 x 1 female


    88 mm from flattener (sold separately)

    Tube weight

    11.7 kg (including tube rings and dovetail bar)

    Tube length

    876 mm (738 mm with retracted dew shield)

    Tube diameter

    148 mm

    Dew shield diameter

    179 mm




    • SharpStar AL-140ED f/6.67
    • 148mm tube rings
    • Losmandy style dovetail bar
    • Adapter to 2" and 1.25"
    • Foam-lined aluminium case
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