Vixen Telescope SD103SII Optical Tube Assembly

Vixen Telescope SD103SII Optical Tube Assembly
Vixen Telescope SD103SII Optical Tube Assembly


Suggested retail price: Contact local dealer

103mm aperture SD apochromatic refractor introducing a new spacer ring for more beautiful astrophotography

It is the successor to the favorably reviewed SD103S as a photo-visual optical tube that is the SD series of apochromatic refractors. With an aperture of 103mm and a focal length of 795mm, you can use it for a wide variety of purposes, from visual observation to astrophotography. We changed the spacers used around the outer periphery of the objective lens from three pieces of foil fragment to the shape of a ring to uniform the diffraction light of star image. It has obtained you a more beautiful star imae. In combination with an optional SD Flattener HD Kit and an optional SD Reducer HD Kit, it develops into a high-performance astrograph providing an image circle of 44mm suitable for a camera/CMOS camera with a full frame imaging sensor.

Vixen Telescope SD103SII Optical Tube Assembly Description

  • Improved spacers for beautiful star images

    In the former SD103S optical tube, small fragments of tin foil are set at three places evenly around the lens as spacers. The small fragments that appear inside the effective aperture of the lens as protrusion generates diffractions around the star image by the light of incidence, resulting in three breaks radially around the star image. You get the star image beautifully as the diffraction light becomes uniform by exchanging the small fragments for a ring-shaped spacer.

  • High-performance SD glass lens that suppresses color fringing

    In the refractor that gathers light using a lens, color fringing (chromatic aberration) occurs by the difference in refractive index from different wavelengths (colors) of the light that passes through the lens. Then, an invention was extra-low dispersion glass to eliminate the chromatic aberration. This glass shows less dispersion in different wavelengths of light, and its refractive index at a particular wavelength shows a value different from that of glass for general use. The SD103SII uses an SD glass (Super ED) lens made from FPL53 glass, a material that exhibits particularly excellent optical performance among ED glass. As a result, it successfully suppresses chromatic aberration at a high level and produces star images clearly and sharply.
    In the SD glass lens, g-ray, C-ray, F-ray, d-ray, and e-ray all come near the 0 value. That indicates the lens is excellent because the chromatic aberration is held at an extremely low level over all the visible colors. In particular, remarkably reduced aberration of the g-ray (purple) that is short wavelength enhances star images crisply.

  • Prepared to meet a wide range of purposes from visual observation to astrophotography

    By setting a reasonable focal length (795mm) for the objective effective aperture (103mm), you can use it for a wide range of purposes, from planetary observations to photography of nebular and star clusters. The supplied flip mirror diagonal allows you to switch the optical path with a knob to straight through or vertical orientation quickly. Two eyepieces with different magnifications are usable quickly. You readily switch between visual observing and photography by attaching a camera on one side and an eyepiece on the other. The SD103SII is equipped with a standard dovetail attachment plate and a metal carry handle. Those accessories make you easily attaching to and detaching from the mount and transporting the optial tube.

  • Available for full-frame DSLR cameras/CMOS cameras, suitable for high-quality astrophotography

    In combination with an SD Reducer HD Kit and an SD Flattener HD Kit (both sold separately), you will be ready to take high-quality astrophotography with a full-frame DSLR camera or CMOS camera.

  • Your "Must" items for astrophotography: Taking photography of nebulae and star cluster

    ●SD Reducer HD Kit (Optional)
    It is a kit for astrophotography that includes a flattener lens, a reducer lens, and a connection ring available for SD81SII, SD103SII and SD115SII optical tubes. Flattening the imaging field of view improves the photographic performance. And the reducer lens reduces the focal length by approximately 0.79 times. Vixen's highest level of anti-reflection coatings (99.9% or more of light transmission per surface) is applied to prevent light loss thoroughly, resulting in a clear image with high contrast. It will bring your taking astrophotography to the next level.

    A wide image circle of 44mm is secured to cover the imaging field of view of a full-frame (36mm x 24mm) DSLR/CMOS camera. A combination of a flattener lens and a reducer lens enables you to use two focal lengths (For instance, with an SD103SII, 811mm and 624mm in the 35mm format). So, you can enjoy shooting a variety of nebulae and star clusters with prime focus imaging.

    ●Wide Photo Adapter 60DX
    Camera adapters for prime focus astrophotography with enhanced accuracy and durability are available for Canon EOS (EF mount) and Nikon (F mount). The integrated adapter with the camera mount reduces vignetting. It is highly effective when shooting with a full-frame DSLR camera. It is attached directly to the SD Reducer or SD Flattener HD Kit.

    ●Dual Speed Focuser (Optional)
    You can adjust the focus at two stages, coarse and fine, by attaching it to the focus knob. The fine focus knob adjusts focus at a ratio of 11:1 compared to the standard focus knob, it demonstrates outstanding effectiveness in situations where fine focusing is required, such as when taking astrophotography or observing at high magnification.

  • 7x50mm Finder II with Illuminated Reticle (Eyepiece unit detachable*)

    A finder scope/guide scope for astronomical telescopes with a magnification of 7x and a 50mm aperture. It has crosshairs and a built-in dark field illumination, which can illuminate the crosshairs in red for sighting easily in a dark field of view. The brightness of the illumination is adjustable step by step for your preference. The eypepiece unit is a detachable type with a 31.7mm sleeve, and you can use the finder scope as a guide scope by exchanging the eyepiece unit for a commercially available CMOS camera** with a 31.7mm sleeve.

* Although you can insert 31.7mm eyepieces sold separately in the place of the eyepiece unit, this will not work as it does not reach focus.
** Regarding appplicability with the CMOS cameras, you make sure that the distance from the 31.7mm visual back (rear end) on the scope body to the surface of an imaging sensor of a camera is about 15mm long or less.


SD103SII Optical Tube Assembly

  • Objective lens, effective aperture
    103mm / SD apochromat, multi-coated SD(Super ED)glass lenses
  • Focal length (F ratio)
  • Resolving power, limiting magnitude
    1.13 arc seconds, 11.8
  • Light gathering power
    217x unaided eye
  • Focusing mechanism
    Rack-and-pinion, with lock knob
  • Adapter thread / Visual back
    60mm and 42mm for T-ring / 50.8mm and 31.7mm push fit with flip mirror diagonal
  • Finder scope
    7x50mm Finder II, dark field illumination, 7 degrees field of view
  • Accessories
    Tube rings, dovetail attachment plate, metal carry handle
  • Dimensoins / weight
    115mm O.D. x 810mm long, 5.5kg (Net 3.6kg)
  • Photography
    Uable with eyepiece projection, prime forcus, afocal imaging**
  • Solar observation
    Available with optional Sun projection screen set B
  • *:Optional 50.8mm eyepiece adapter is needed.
    **:A camera adapter fitting to your camera is separately needed.


  • SD103SII OTA
  • Flip Mirror Diagonal
  • Dovetail Attachment Plate
  • 7x50mm Dark-field Illuminated Finder Scope II
  • 50mm XY Finder Bracket II
  • Instruction Manual
For availability of products, please contact our local dealers. The specifications are subject to change without notice.

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