Vixen VSD90ss F5.5 Astrograph with large image field

Vixen VSD90ss - apochromatic 90 mm f/5.5 astrograph with large image field

Fast 90 mm high-performance astrograph for demanding astrophotographers and observers, featuring 5 lens elements in 5 groups

Due to the complex optical structure with five lens groups and five elements (quintuplet), including two SD (Super ED) lenses and an ED lens (Extra-low Dispersion) , a virtually aberration-free optical system was created.

This revolutionary astrograph is compatible with a full-frame digital DSLR or an even larger 44x33 mm camera. The 90 mm astrograph with fast focal ratio delivers exceptionally sharp, high-contrast and small point stars from the centre to the corners of the field of view. In addition, it is also ideal for visual observation with a very large field of view but also for planetary observation with high magnification.

The VSD90ss is designed so that there is a "long peak range" in the adjustment accuracy of the sharpness, so that photographers can always achieve satisfactory results in astrophotography. Even if the focus is not quite precise, round and sharp stars are still shown throughout the entire image field.

The VSD90ss is coated with the most modern coatings of extremely high reflectivity. These coatings have been specifically developed to optimize the properties of each individual lens element without degrading contrast and light intensity across multiple lenses.

Illumination without vignetting
In most cases, an astrograph also produces optical vignetting (a gradual decrease in light rays towards the edge of the image) This is mainly caused by rear lenses being shaded by the front lenses. Because of this darkening, it is relatively normal for the photographer to have to further edit the image after taking the picture and also have to do some additional so-called flats before taking the picture. To solve this problem, the VSD90ss uses wide aperture lenses in the rear elements, securing over 90% of the light volume at the edge of the 60 mm image circle. Since the light intensity is uniform throughout the entire image field of the VSD90ss, there is no need for complex technology to prevent edge darkening.

Please note: Depending on the recording system used, mechanical vignetting can still occur due to the camera body or incorrect adapters.

96.7% Strehl for impressive visual observations
The VSD90ss offers a flattened large field of view with a low magnification wide angle eyepiece. Even with a high-quality wide-field eyepiece with a large field of view, you can get sharp images of stars in the entire field of view when visually observing!

In the centre of the field of view, a Strehl intensity of an impressive 96.7% is achieved at visible wavelengths. This Strehl ratio exceeds that of the SD81SII apochromat at 95.7%, which is known for its excellent optical properties, and this also works excellently when observing the moon and planets at high magnification.

The versatile large and stable focuser
The VSD90ss has a large focuser with a diameter of 87.5 mm to make optimal use of the large illumination field of 60 mm. With the large focuser that is compatible with many accessories, it is perfect for astrophotography up to medium format or 35 mm full frame DSLR cameras. Thanks to its precise manufacturing, it is also suitable for very heavy cameras without tipping.

The precision locking lever of the focuser
The focuser´s drawtube has a locking lever that holds the drawtube firmly in position even when using heavy cameras such as medium format cameras or CCD cameras with a large sensor. The locking lever clamps the rack gear to the drawtube so that the viewing angle or focus on your camera does not shift.

Compatible with motor driven focusers
To provide sensitive focusing, an optional dual-speed motorized focuser is in preparation. An EAF (Electronic Automatic Focuser) from ZWO can also be retrofitted. The available models of the EAF are linked below, no further adapters are required for connection to the telescope.

Optional VSD Reducer for even faster results
The tried and tested optional VSD reducer, which was also used on the predecessor, the VSD 100, is also compatible with the VSD90ss. The photographer gets even faster results in astrophotography with a focal ratio of f/3.9.

- VSD90ss astrograph
- Dust caps for front lens and exepiece holder

Safety informations: PDF Download