The Vixen VSD 100mm f3.8 Astrograph features an innovative wide and flat imaging field, that covers 645 medium format cameras. The 5 elements in 5 group lens design completely eliminates a 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 scope achieves superb color correction. The blue halos around stars, that are visible in astrophotography and are hard to reduce with a 4 elements in 4 group lens design, are corrected successfully. In addition, astigmatism and coma aberrations are corrected to an extremely high level of image quality. The VSD 100 comes with an aluminum storage case. The Strehl intensity on the lens design of the VSD100F3.8 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 detect 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 VSD100F3.8 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. (Patent pending). 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. " Examples of Tony's images above. Precision Glass Annealing Process and a Premium Zygo Verifier ATZ Laser Interferometer. 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.


Spot Diagram Center of frame; Edge of full frame 35mm ;Edge of a digital 645 format; Edge of full frame 645 format ;4 elements in 4 group F3.8 optics (designed for reference)

Spatial frequency: Sagittal; Meridional; 10 lines / mm; 30 lines /mm; Distance from center of frame

Precision Over-sized Focuser and Large Rubber Focus Ring The VSD100F3.8 Telescope 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.

Precision Over-sized Focuser and Large Rubber Focus Ring The VSD100F3.8 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.

Objective Lens	Objective lens design	SD Apochromatic, fully AS coatings, 5 group-5 element design (SD lens x1, ED lens x1
	Effective Aperture	100mm
	Focal Length	380mm
	Focal Ratio	f/3.8
	Light gathering power	204x unaided eye
	Resolving Power	1.16 arc seconds
	Limiting Magnitude	11.8
	Image Circle	70mm, approx. 60% illumination a the edge (covering 645 format)
Focuser	Drawtube diameter	89mm
	Adapter threads dia	M84-pitch 1mm, M60-pitch 0.75mm, M42-pitch 0.75mm
	Push fit	60.2mm, 31.7mm
	Filter threads dia	58mm
Size & Weight	Optical tube length	497mm
	Optical tube diameter	115mm(*SX tube ring 115mm is not compatibel)
	Optical tube weight	4.5kg
	Accessories	Aluminum case, Allen wrench 1.5mm
	Optional Accessories	VSD Tube Ring 115mm, Finder Bracket shoe, Camera Mounting adapter for 645D, VSD focal Extender 1.58x, VSD Focal Reducer 0.79x