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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.

 

Mechanics

 

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.

 

Specifications

Optical
Optical design Fluorite Doublet
Optical mounting Air spaced (Fluorite in front)
Optical coatings Fully Multi-Coated
Aperture 90 mm
Standard
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°
Mechanical
Tube length 480mm - 560mm (80mm retractable dew shield)
Tube diameter 95 mm
Tube weight 3,2 kg
 

Spot diagrams

SKY-90 refractor Spot-diagram

System-charts

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