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