Vixen VC200L - 8" f/9 Modified Cassegrain OTA
Vixen VC200L - VISAC (Vixen Sixth-Order Aspheric Cassegrain) Optical System
The Vixen VC200L’?????????s catadioptric VISAC (Vixen Sixth-Order Aspheric Cassegrain) optical system is one of the most sophisticated optical designs available on the market today: free of coma, curvature of field, spherical and chromatic aberration. Especially noteworthy in the Vixen VC200L is its sharpness and flatness at the edge, which far exceeds that of Schmidt-Cassegrain systems of the same aperture. It provides a pinpoint star image less than 15-microns, even at the edge of its 42mm image circle. If you are looking for a photographic catadioptric, the Vixen VC200L is an excellent choice.
The Vixen VC200L telescope features the VISAC optical system. The VISAC optical system is composed of a concave primary mirror, a convex secondary mirror and a three-element field corrector at the base of the focuser. The primary mirror is a unique innovation: a precise sixth-order shape produced by Vixen's High-Precision Poly-Order Aspherical Mirror Molding Technique.
The Vixen VC200L is well suited for observation and astrophotography of the moon, planets, star clusters, nebulae, and comets. The rack-and-pinion focusing mount accepts optional 2’????????? eyepieces and accessories, and an f/6.4 reducer for photographic use is also available. The open tube design of the Vixen VC200L eliminates the dew problem that is common with conventional Schmidt- or Maksutov-Cassegrain systems and its size makes it very easy to handle. The new white VC200L telescope has a lighter-weight optical tube with improved anti reflection coatings, a metal carrying handle and now comes standard with a 7x50mm finderscope.
A Few Words on the Vixen VC200L Telescope
"The focuser with which the VISAC is fitted is simply wonderful. It is an independent rack & pinion model mounted behind the primary, which remains stationary. Most Schmidt-Cassegrains suffer from mirror shift, to one degree or another. Companies have done their best to minimize this common issue, but it is still present in the many models I’?????????ve tested. The typical Schmidt-Cassegrain is focused by moving the primary optic back and forth, in effect changing the focal length of the optical train to match the location of the imaging sensor or eyepiece focal point, rather than moving those elements to a fixed focal point. This mirror shift can sometimes cause target objects to shift on the focus plane during focus and can be quite troublesome while imaging deep sky objects. Because the VISAC primary stays stationary, mirror shift induced image shift is essentially eliminated. Another interesting feature is the VISAC’?????????s metal side plate which runs along one side of the dovetail plate. This brilliant idea prevents the clamp screws of the saddle plate from marring the dovetail plate and should be incorporated on other designs. Another nice feature is a carrying handle located on top of the OTA. This proved to be very useful when lifting the optical tube on and off the mount. Overall, the visual image quality of the VISAC was quite impressive, particularly considering how portable and light weight it is. It is a step up in image quality from the typical Schmidt-Cassegrain in my opinion, particularly with regard to edge sharpness. Although the VISAC costs nearly double what an 8-inch Schmidt-Cassegrain optical tube does, I think it’?????????s worth it!" -- Daniel Mounsey, "Astronomy Technology Today"
Vixen VC200L - VISAC (Vixen Sixth-Order Aspheric Cassegrain) Optical System Features
- Optical Tube Dimensions of 24.4" x 9.13" (620mm x 232mm) length x diameter and Weight of 13.2 lbs (6 kg) for exceptional portability.
- Limiting Visual Magnitude of 13.3 and outstanding Theoretical Resolution factor of 0.63".
- Primary mirror is held by a retaining ring, instead of hooks to decrease flare and enhance contrast.
- Lighter weight optical tube and improved anti-reflection coatings.
- High-definition star images to the edge of a wide viewing field and offers exceptionally outstanding performance in astrophotography.
- Excellent image correction throughout the large illuminated field. (42mm diameter fully illuminated).
Vixen Product Number: VX-2632