Askar 107PHQ F/7 Quadruplet Flat Field Astrograph

Brand: Sharpstar / Askar


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  • 107mm Aperture with Excellent Light-gathering Ability
  • f/7 Focal Ratio for High Magnification
  • Quadruplet air-spaced APO (including two ED glass)
  • Contractable Dew Shield

Product Details

  • The first long-focal-ratio Flatfield astrograph from Askar, the 107PHQ is born with a special mission: taking high-quality astronomy images. Whether you are just getting started in astrophotography, or an experienced amateur with years of observing under your belt, the Askar 107PHQ will meet your needs.

    What is an Astrograph?

    An astrograph is a specialized telescope designed specifically for astrophotography and is not well suited for visual observing or making general astronomical observations. Although it is possible to use them visually, the extra cost associated with astrographs make them a better value for astro-imaging - their special characteristics aren’t used in a visual setting.

    Taking images of the night sky is a specialized use-case for telescopes. As we often say in this hobby, ‘There is no such thing as the perfect telescope.’ We say that because there are so many different objects to look at in space and each one has different requirements to see it.

    Dim, large things like galaxies and nebulae require big apertures, a wide field with lower magnifications which means short focal lengths.

    Bright small things like planets don’t need aperture because they are brighter, instead we want more detail, higher magnifications and longer focal lengths.

    What’s more, telescopes with cameras attached work differently than one designed for use by a human eyeball. This is why you see so many accessories like field-flatteners, telecompressors, filters, etc for an imaging telescope you don’t see for visual observers.

    Cameras can also do things an human eye cannot, most notably collect photons over a long time to compensate for aperture size, light pollution, etc.

    These differences mean we can’t just buy one telescope to do all things and astrographs are a special telescope designed to do one thing and do it well: take pictures of the night sky.

    The Askar 107PHQ

    Most of the popular refractive astrograph designs available recently consist of a triplet refractive objective, followed by another lens in the optical tube that flattens the field. This field-flattener is placed after the objective and before the focuser.

    This arrangement means that issues like knowing a particular back-focus for a given optical setup are gone, there is one fixed place for your camera in all settings. Because everything to take a good image are inside the tube: color-corrected lenses and field flattener, there isn’t a change in focus for any given camera or adapter.

    The 107mm aperture makes the Askar 107PHQ highly versatile without giving up portability. Planets are very bright without chromatic aberration and the stars in the edges of a field with a deep-sky nebula or galaxy are pinpoints - no curved, distorted stars!

    The relatively longer focal length of 740mm makes this an f/7 telescope that is surprisingly versatile. Planetary detail along with relatively wide fields makes this a telescope that captures great images both of planets and nebulae.

    Interestingly for an astrograph, users report that the Askar 107PHQ is also a nice choice for visual observations. It can accommodate 1.25" and 2" zenith mirrors as well as various eyepieces providing a perfect focus. It can even be used to observe planets with a high magnification eyepiece. The built-in field flattener isn’t something the human eye will take much notice of, but the views are wonderful!

    Optical Design

    Askar 107PHQ is an f/7 astrograph and has four optical elements, including two pieces of ED glass, which can better reduce chromatic aberration. It can achieve excellent color correction even with the magnification mounting to 300× in visual observation.

    The sleek 107PHQ is assembled with high-quality CNC-machined components and wrapped in a smooth coating. All focus knobs and mounting rings are a decorative bright green. The 3.4-inch rigid focuser is capable of handling a load of 8kg and has a long travel distance of 95mm, which is suitable for visual observation.

    The built-in field-flattening lens supports 44mm full-frame imaging. The stars around the corner of the images seldom suffer from distortion or deformation. At the center of its field of view, the RMS radius is only 3um and stars are pinpoints all the way out to the edge of the field of view.

    The standard package includes an Askar 107PHQ OTA, a set of four-piece M86-M48 adapters, a pair of tube rings, a 300mm Askar Vixen-style dovetail plate and a high-quality aluminum suitcase.

    Maximum accessory connection (with the focuser fully retreated):

    Imaging mode:

    • 79mm (from the base of M48×0.75 male thread)
    • 99mm (from the base of M54×0.75 male thread)
    • 119mm (from the base of M68×1male thread)
    • 149mm (from the base of M86×1 male thread)

    Observing mode:

    • 120mm (from the end of 2" visual back)
    • Total length:603mm(when the dew shield is contracted)
    • 754mm(when the dew shield is stretched)

    Rear-end thread type:M86×1 to M68×1

    • M68×1 to M54×0.75
    • M54×0.75 to M52×0.75
    • M52×0.75 to M48×0.75(with M48×0.75 filter thread)

    Four-piece photographic adapter:M48×0.75

    Mechanical Diagram


  • specifications

    Aperture107mm (4.25")
    Corrected Image Circle44 mm
    Focal Length749mm
    Focal Ratiof/7
    Optical DesignQuadruplet
  • included items

    • Askar 107PHQ OTA
    • Pair of tube rings
    • Askar 300mm Vixen-style dovetail plate
    • Set of four-piece M86-M48 adapters
    • High-quality aluminum case

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