Vixen VSD100 f/3.8 Astrograph Refractor OTA
Here is Tony Hallas' Initial test review of the Vixen VSD 100mm f3.8: "The telescope is essentially sensational. It accomplishes the impossible ... a totally flat field across the huge 16803 chip with superb color correction at f/3.8. It is mechanically superb as well, supporting the heavy 16803 camera without any complaint and the enormous helical focuser is tight and accurate. The telescope exhibited good thermal stability appearing to hold focus even as the temperature was dropping. This is significant for an f/3.8 optic. With its extremely fast optics, flat field, and superb color correction it is a unique product, not a rehash of "more of the same."(See Tony Hallas' Image below)
The innovative wide and flat imaging field, that covers 645 medium format cameras, and 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 VSD100 comes with an aluminum storage case.
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 and is ideally suited to detect faint stars. The image circle is as large as 70mm in diameter (60% illuminated). Star images are as small as @ 15 microns around the corners, resulting in excellent field flatness.
The lenses of the VSD100 f/3.8 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).
Precision Over-sized Focuser and Large Rubber Focus Ring:
The VSD100 f/3.8 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.
Vixen Product Number: 26145
- Additional Information
SKU VX-26145 Manufacturer Vixen Telescope Series Vixen VSD Optical Design Astrograph Mount Type None - Optical Tube Only Warranty 5 Year Warranty Telescope Aperture 4" Telescope Focal Length 380mm Telescope Focal Ratio f/3.8 Optical Coatings Not Provided by Manufacturer Tube Color or Finish Gloss White Case Included? Yes
- Included Items
- Vixen VSD100 f/3.8 Astrograph Refractor OTA
- Aluminum Carry Case
- Oversized Precision Focuser
- Large Rubber Focus Ring
- Questions & Answers
Product QuestionsHello, What is the backfocus of the Vixen VSD 100 f/3.8 and where is it measured from on the OTA? Thanks!
jgIn my experience manual focusing, even when assisted by software like Maxim DL, is approximate at best. That is why I use FocusMax to get the best possible focus on my CCD chip. How is perfect focusing achieved with the VSD? Thanks,Question by: Gekorana on Aug 11, 2014 2:40:17 AMBecause of the limited back focus on the VSD 100 f/3.8, the best way to automate focus may be with a Robofocus and belt drive. The VSD is very similar to the older Pentax 100mm f/4 in design (same designer) and the Pentax 100 and 125 could be automated with a setup like this: http://www.astromart.com/images/classifieds/655000-655999/655199-2.jpg. Technical Innovations has the measurements for the older Pentax scope, but they may need new measurements for the VSD.
Depending on your camera, you might also be able to mount a crayford focuser, but the camera would have to be shorter than around 20-30mm (one shot color only). For a monochrome camera with filter wheel, you either need an FLI Atlas focuser or something like the Robofocus setup.Answer by: Chris (Admin) on Aug 12, 2014 11:50:20 AM
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