Vixen VSD 100 f/3.8 Astrograph Refractor OTA

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Item #VIX363-1

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  • $5,999.00
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  • $5,499.00
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  • f/3.8 Astrograph with 5 elements in 5 groups
  • Inclusion of SD and ED lenses achieves amazing color correction
  • Flat, wide imaging field covers 645 medium format cameras
  • Star images are as small at @ 15 microns around corners
  • High-tech coatings match characteristics of each lens element
  • Oversized helical focuser can hold heavy cameras easily
  • Vernier scale displays focus graduations as small as 20 microns
  • Comes with aluminum case
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  • Description

    The Vixen VSD 100 Astrograph offers a wide and flat imaging field that covers 645 medium format cameras.  The 4" optical set is a 5 element /5 group design that completely eliminates the violet tint in chromatic aberration (blue halo). With an SD lens in the front objective group and an ED lens in the rear objective group, this telescope achieves superb color correction. Blue halos around stars that are visible in astrophotography are hard to reduce, even with a 4 elements in 4 group lens design, but in the VSD design they are corrected successfully. In addition, astigmatism and coma aberrations are corrected to an extremely high level of image quality. The Strehl intensity on the lens design of the VSD100 f/3.8 is better than that on a 4 elements in 4 group lens design by approximately 10%. It does not decrease abruptly on stars away from the center of a photographic field. It is ideally suited to detecting faint stars. The image circle is as large as 70mm in diameter (60% illuminated). The star images are as small as @ 15 microns around the corners, resulting in excellent field flatness.

    The lenses of the Vixen VSD 100 f/3.8 Astrograph have the most up-to-date coatings of extremely high reflectivity. These have been developed to match the characteristics of each lens element in order to avoid the deterioration of image contrast due to the increase of lens elements. It boasts of a 99.9% light transmission at the maximum per lens surface and achieves superb images with extremely high contrast with no ghost and no flare images.

    Tony Hallas says: "To have this level of performance from an f/3.8 is remarkable. All in all..a very impressive little telescope! The telescope is essentially sensational. It accomplishes the impossible. Mechanically superb as well, supporting the heavy 16803 camera without any complaint and the enormous helical focuser is tight and accurate. With extremely fast optics, flat field, and superb color correction it is a unique product not just a rehash of the same." 

    In the process of manufacturing optical glass, all the five lens elements are annealed with a precision annealing process.  The annealing can straighten molecular arrangements of lens elements and thus unify the characteristic of optical glass. The homogeneity of refractivity in optical glass is enhanced to the highest degree.  

    The Vixen VSD 100 f/3.8 Refractor has an oversized focuser that can be attached to the 645 medium format cameras without difficulty. Highly accurate focusing is possible with the non-rotational helical fine focuser, where the distance of drawing in and out the focuser can be read as small as 20 microns with the provided vernier scale. All the graduations are engraved.  The Vixen VSD 100 also comes with an aluminum storage case. 

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    What's Included

    • Vixen VSD 100 Refractor Astrograph
    • Aluminum Case
    • Lens Cap
    • Allen Wrench

  • Dimensions & Specifications

    Optical Design:

    SD Apochromatic Refractor

    Lens Elements:

    Five, with 1 SD and 1 ED

    Lens Groups:



    100 mm

    Focal Ratio:


    Focal Length:

    380 mm

    Focuser Drawtube Diameter:

    89 mm

    Focuser Adapter Thread Diameter:

    M84 pitch 1 mm, M60 pitch 0.75 mm, M42 pitch 0.75 mm

    Focuser Push Fit:

    60.2 mm, 31.7 mm

    Focuser Filter Thread Diameter:

    58 mm

    Image Circle:

    70 mm

    Resolving Power:

    1.16 arc seconds

    Limiting Magnitude:


    Light Gathering Power:


    OTA Diameter:

    115 mm (Requires VSD 115 mm Tube Ring)

    OTA Length:

    497 mm

    OTA Weight:

    9.92 pounds

    Mounting Type:

    Rings, sold separately

  • Product Guarantee

    We stand behind all the products we sell, and your satisfaction is our top priority. If you're not satisfied with the quality of your purchase, simply send the item back to us in its original packaging within 30 days of its delivery.

    Manufacturer Warranty

    Default manufacturer warranty.

    Return & Exchange Policy

    At our site, returns are easy! You may return new, unused, and resalable items for a refund or exchange. Simply ensure that the item is returned in its original product packaging within 30 days of delivery.

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