SKY-90 Scope

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The SKY-90 is the ideal compromise between a wide-field astrograph and general-purpose observation refractor.

The SKY-90 is the ideal compromise between a wide-field astrograph and general-purpose observation refractor. Its great compactness makes it an excellent companion for the itinerant astrophotographer. Equipped with an apochromatic objective with Fluorite doublet of 90mm of aperture (F/5.6), it constitutes an unequalled optics for those wishing to have a transportable and general-purpose telescope, of a frightening effectiveness. Light, it does not require massive mounting.

A vast range of accessories makes it possible to cover the large uses of amateur astronomy, in particular two specific accessories, a focal reducer (F/4.5) and a 1.6x extender.


Apochromatic objective with Fluorite doublet


The SKY-90, in spite of its short focal distance, is adapted to all the fields allowed by its aperture, thanks to its very wide chromatic correction and thanks to some subtle compromises : a light under-correction of the spherical aberration at prime focus, the Extender-Q/corrector 1.6x optional addition and an objective assembled on adjustable barrel.




In order to fulfill the pointed requirements of imaging, the SKY-90 does not make any concession on mechanics. It is equipped with a precise, tighted rack-and-pinion focuser as well as a device of blocking the focuser course. The focuser end offers a 50.8mm adapter which it is placed very in front of the focal plane, to allow a great combination of accessory assemblies, including with imagers equipped with large CCD sensors.


Retractable dewshield


The SKY-90 is of an exceptional compactness. Once the dewshield retracted, the length of the optical tube assembly is only of 480mm, except optional accessories placed at prime focus. A considerable asset for all those willing to have a transportable instrument for the imaging and for the observation. The tube weighs only 3,2 kg.



Optical design Fluorite Doublet
Optical mounting Air spaced (Fluorite in front)
Optical coatings Fully Multi-Coated
Aperture 90 mm
Focal length 500 mm
Focal ratio F/D 5,56
Resolution 1,29"
Limiting magnitude 11,5
Light grasp 165x
With reducer
Focal length 407 mm
Focal ratio F/D 4,5
Image circle 45 mm
Photo field 6,3°
Tube length 480mm - 560mm (80mm retractable dew shield)
Tube diameter 95 mm
Tube weight 3,2 kg

Spot diagrams

SKY-90 refractor Spot-diagram


SKY-90 system-chart (visual/photo) Download  
SKY-90 system-chart with Extender-Q 1.6x (visual/photo) Download