Astronomy Specialist



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The Sharpstar 100Q-II is a professional apochromatic Petzval quadruplet with a focal ratio of f/5.8 and a corrected field of 44mm in diameter.

The lenses are assembled in two groups: an air-spaced doublet on the front and a doublet towards the focus. The objective lens includes one FPL53 Ohara glass with extra low dispersion priorities for a superb chromatic correction.

Differently from standard ED triplets, the SharpStar 100Q uses a singlet on the optical path that does not have to be set to a specific distance to the camera sensor. That leaves the freedom to use any filter wheel, any off-axis guider or accessory before the camera sensor without any worry to calculate the correct distance from the flattener. 

With a large 44mm fully corrected image circle and a focal ratio of f/5.8, this is the perfect astrograph for the advanced astrophotographer. The large rack and pinion 3.2" focuser has a massive 5.5kg payload, it can be rotated 360° to perfectly frame the subject and it has a reduction gear of 10:1 for precise focusing.

All the lenses are fully multi-coated and the tube is internally blackened 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.

    Sharpstar 100Q-II

    Every SharpStar telescope is inspected on the optical bench by Testar and guaranteed against defects. To ensure optimal performance, the collimation of every telescope is tested using a GMK collimator. This instrument incorporates 4 LED lights that are oriented towards the objective lens and a symmetrical reflection of these lights is a synonymous of a good collimation. Here is a sample of the certificate attached to every tested Sharpstar.


    GMK collimator on SharpStar 100Q II

    GMK collimator on SharpStar 100Q II


    This telescope works at its best with its own focal reducer and corrector delivering a fully corrected field of view for the full frame sensors. The CCD inspector results shows that across the entire full frame this telescope produces a "curvature" of only 17.7%. That means at the corner of a full frame sensor, stars are only 17.7% larger than in the center. For more information about CCD Inspector, please read this article in the Testar blog. 

    CCD Inspector results with SharpStar 100Q II.


    Vignetting 100Q

    The field is truly fully illuminated for the entire full frame format. The maximum vignetting is only 3 - 4% at the corner of the sensor.



    Optical design

    Apochromatic Quadruplet (triplet objective + singlet corrector)

    Objective diameter

    100 mm

    Focal length

    580 mm

    Focal ratio


    Resolving power

    1.20 arc second

    Stellar limiting magnitude


    Max. magnification

    200 x

    Light gathering power

    329 times the human eye

    Mount attachment

    Vixen style bar (150 mm long)


    Rack & pinion dual speed (10:1) 3.2" diameter

    Camera connection




    Tube weight

    5.2 kg (including tube rings and dovetail bar)

    Tube length

    600 mm (508 mm with retracted dew shield)

    Tube diameter

    114 mm

    Dew shield diameter

    134 mm




    Sharpstar 100Q-II

    Sharpstar 100Q-II f/5.8


    • SharpStar 100Q-II f/5.8
    • 114mm tube rings
    • 150mm Vixen style dovetail bar
    • Handle on the rings
    • Foam-lined aluminium case
    • Adapter to 2" and 1.25"
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