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 triplet on the front and a singlet towards the focus. The objective lens includes one Extra Low  Dispersion glass for a superb chromatic correction.

Differently from standard ED refractors, the SharpStar 100Q-II features a Petzval design that does not require to set the sensor to a specific distance to the last lens. That leaves the freedom to use any filter wheel, any off-axis guider or accessory 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 capacity, it can be rotated 360° to perfectly frame the subject and it has a reduction gear of 10:1 for precise focusing. 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.

    Sharpstar 100Q-II


    Every Sharpstar telescope is inspected on the optical bench by Testar and is guaranteed against defects. To ensure optimal performance, we test every single telescope on an optical bench, using an artificial star in autocollimation. This test can easily reveal the presence of optical defects such as spherical aberration, astigmatism, zonal errors, coma or optical elements out of collimation. The light from the artificial star travels from the eyepiece holder through the lenses and it gets reflected by a high quality Zerodur flat mirror with a correction peak-to-valley of λ/20. Then, the light travels back through the lenses, gets divided by a beam splitter, then is magnified by a high quality Barlow and finally analysed with an eyepiece and a camera. This is a test in double pass and any optical aberration gets magnified twice and therefore optical errors can be easily detected. 

    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) air spaced
    Objective diameter 100 mm
    Focal length 580 mm
    Focal ratio f/5.8
    Resolving power 1.20 arc seconds
    Stellar limiting magnitude 12.0
    Max. magnification 200 x
    Light gathering power 329 times the human eye
    Mount attachment Vixen style bar (150 mm long)
    Focuser Rack & pinion dual speed (10:1) 3.2" diameter
    Camera/eyepiece connection M82 x 0.75 Male; 2"; 1.25"
    Backfocus 120.5mm (from the base of the M82 thread)
    Tube weight 5.2 kg (including tube rings and dovetail bar)
    Tube diameter 114 mm
    Dew shield diameter 134 mm
    SKU SS-100QII

    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 M82 to M48
    • Adapter M82 to 2"
    • Adapter from 2" to 1.25"


    The Horsehead Nebula - Sharpstar 100Q-II Apo Quadruplet Refractor


    IC434 - Sharpstar 100Q-II © Kurt Ams


    Carina Nebula - Sharpstar 100Q-II Apo Quadruplet Refractor


    Carina Nebula - Sharpstar 100Q-II © Kurt Ams


    NGC 7293 - Helix Nebula - Sharpstar 100Q-II Apo Quadruplet Refractor


    NGC 7293 - Sharpstar 100Q-II © Kurt Ams


    The Sharpstar 100Q-II can be ordered with matching PLUS dovetail & rings from Prima Luce Lab. These are CNC-machined in aluminium and anodized to increase the hardness of the material and to protect it from oxidation.

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