Vixen VSD90ss Astrograph

Very fast 90 mm high-performance astrograph for demanding astrophotographers and observers with 5 lens elements in 5 groups "Made in Japan"

Very fast 90 mm high-performance astrograph for demanding astrophotographers
Elaborate construction with 5 lens elements in 5 groups for absolute correction
Needle-fine stars right up to the edge of the image field, even with 44x33 mm camera format
Almost no vignetting thanks to the large end lenses
Large, stable eyepiece extension, also suitable for heavy cameras
Extremely high sharpness, color purity and contrast thanks to SD lenses
Very large field illumination up to 60 mm
High Strehl intensity of 96.7% at visible wavelengths
Compatible with optional reducer of the VSD 100 for even faster results (F:3.9)
Optional motor focuser with two speeds can be retrofitted

Product information "Vixen VSD90ss Astrograph"
Fast 90mm high performance astrograph for demanding astrophotographers and observers with 5 lens elements in 5 groups. The complex optical design with five lens groups and five elements (quintuplet), including two SD (Super ED) lenses and one ED (Extra-low Dispersion) lens, has created a virtually aberration-free optical system.
This revolutionary astrograph is compatible with a full-frame digital DSLR or an even larger 44x33mm camera. The 90mm astrograph with fast aperture ratio delivers exceptionally sharp, high-contrast and small point-like stars from the center 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 to have a "long peak range" in the adjustment accuracy of the focus so that photographers can always achieve satisfactory results in astrophotography. Even if the focus is not quite right, round and sharp stars are still shown across the entire image field.

Illumination without vignetting

In most cases, an astrograph also produces optical vignetting (a gradual decrease in the light rays towards the edge of the image). This is mainly caused by the rear lenses, which are shaded by the front lenses. Because of this darkening, it is relatively normal for the photographer to have to further process the image after taking the picture and also to take a few additional so-called flats before taking the picture. To solve this problem, the VSD90ss telescope uses lenses with a large aperture in the rear elements and secures over 90% of the light volume at the edge of the 60 mm image circle. Since the light intensity is uniform across the entire image field of the VSD90ss, the complex technology to prevent edge darkening is not required.
The VSD90ss is coated with the most modern coatings with extremely high reflectivity. These coatings are specifically designed to optimize the properties of each individual lens element without degrading contrast and light intensity when multiple lenses are used.

Numerous light gradations bring beautiful point-like stars into the field of view
The low optical vignetting ensures sufficient illumination and thus eliminates the asymmetrical flare caused by bright, diffraction-limited stars. It prevents stars at the edge of the 60 mm image circle from exhibiting deformations such as comets, astigmatism or coma. Since the illumination of the image field is relatively similar from the center to the edge of the image, you can expect excellent star imaging.

Note:
*Mechanical vignetting can still occur depending on the recording system used due to the camera body or incorrect adapters.

96.7 ％ Strehl for impressive visual observations
The VSD90ss offers a flat large field of view with a wide-angle eyepiece with low magnification. Even with a high-quality wide-field eyepiece with a large field of view, you will get sharp images of stars throughout the field of view when observing visually!
At the center 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 great when observing the moon and planets at high magnification.

The versatile large and stable focuser
The VSD90ss has a large eyepiece extension with a diameter of 87.5 mm to make the most of the large illumination field of 60 mm. With the large extension, which is compatible with many accessories, it is perfect for astrophotography up to large format or 35 mm full-frame DSLR cameras. Thanks to the precise manufacturing, it is also suitable for very heavy cameras without tilting.

The precision locking lever of the eyepiece extension
The focuser's extension tube has a locking lever that holds the extension tube firmly in position even when using heavy cameras such as large format cameras or CCD cameras with a large sensor. The locking lever clamps the rack and pinion gear on the extension tube so that the angle of view or focus on your camera does not shift.

Compatible with motor-driven focusers
An optional two-speed motor focuser (optional) is available for the VSD90ss to enable sensitive focusing.
An EAF (Electronic Automatic Focuser) from ZWO or equivalent can also be retrofitted.

Optional VSD Reducer for even faster results
The proven optional VSD Reducer, which was also used on the predecessor VSD 100, is also compatible with the VSD90ss. This gives the photographer even faster results in astrophotography with an aperture ratio of 1:3.9.

Optional accessories
VSD90ss case
VSD 115mm tube clamp

FEATURES

90mm aperture, 495mm focal length (F5.5)
Pinpoint stars to the edge of the field in 44x33mm format
5 lens elements in 5 groups
Image illumination up to 60mm
Resolution: 1.29
Limiting magnitude: 11.5
Light gathering power 165x
Illumination: 60mm
Dimensions: 115mm diameter x 600mm length (476mm length for storage)
Weight: 4.3kg
Connections/threads: Thread size / 84mm (1mm pitch), 60mm (1.0mm pitch), 42mm for T-ring push fit / 60.2mm, 50.8mm and 31.7mm
Solar observation: Solar projection attachment available separately B
Optional VSD100 reducer compatible (aperture ratio F: 3.9)

SCOPE OF DELIVERY

VSD90ss high-performance astrograph
Material: aluminum
Target group [telescopes]: advanced users, specialists and research, visual observers
Connection thread type: 60 mm
Product family [telescopes]: lens telescope
Color: white
Dust cover: for front lens and eyepiece socket
Material front lens or correction plate: Ohara Japan FPL-53 ED glass
Optical design: apochromatic refractor

Product and safety information

Manufacturer:
Bresser GmbH, Gutenbergstraße 2, 46414 Rhede