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SharpStar AL-90II ED APO telescope features:
• 90MM f/6.67 triplet full separation optical design
• Includes one Japanese OHARA FPL-53 Super ED lens
• New 2.5" dual-speed rack and pinion focuser, 10:1 fine focus
• 2" and 1.25" universal interfaces
• Angle adjuster for 360 degree rotation
• Universal (Vixen-style) dovetail bar with tube rings
• Lens hood is equipped with a slide lock
• Comes with a finderscope shoe
 
The Ruixing (SharpStar) AL-90II ED apochromatic refracting telescope tube features a triplet fully separated (air spaced) design that includes one FPL-53ED lens and a full-surface multi-layer coating.
The AL-90II ED provides a very good observation and imaging system thanks to the convenient focal ratio. The unique triplet design incorporates a special ED lens, that helps to achieve excellent chromatic aberration control, the stars are point-like sharp, and the image is more vivid.
Aluminium alloys was used to create the lens barrel material, which looks beautiful and offers a unique style. It also reduces the weight of the lens barrel. The net weight of the whole OTA is only 3.4 kg, which is very easy to carry.
The SharpStar AL-90II also comes with an impressive focusing system while providing an excellent optical system. The SharpStar AL-90II ED comes with a precision 2.5" rack and pinion dual speed focuser. Compared with many refractors on the market, the use of a rack and pinion focuser offers larger payload and a stronger hold, so that your focuser will not slip and you don’t need to be worried about being out of focus or badly framed image when using heavy-duty observation accessories or camera. The 360-degree rotator allows you to easily rotate the shooting angle and correct the framing to your own satisfaction. The focuser's 2" and 1.25" international standard interface with brass compression ring does not let your accessories to scratch. More importantly, its 2.5-inch focusing tube (drawtube) is more robust and more stable than most commercially available 2-inch focusing tubes. It also provides good upgrades for heavy-duty accessories such as large-caliber field flatteners.
In addition, the AL-90II ED can be equipped with a dedicated 2-inch or 2.5-inch large field flattener for astrophotography, which provides excellent image quality and avoids field edge star distortion. The use of a field flattener is simple, the smaller 2" field flattener will slide into the 2" eyepiece holder barrel or the 2.5" flattener will be screwed into the focuser. In both cases the other side screws into the camera via optional (camera-specific) adapter. This provides a safe and secure connection for your expensive camera.
The SharpStar AL-90II APO is a reasonably priced observational and imaging tool with high quality triplet optical system that features exotic FPL-53 super ED glass, high quality heavy duty 2.5-inch rack and pinion focuser; when compared to other similar products on the market, its value is self-evident.
 
Product parameters:
Model: Ruixing (SharpStar) AL-90II
Objective type: triplet fully separated (air spaced) APO (one of which is FPL-53 ED glass)
Aperture: 90 mm
Focal length: 600mm
Focus ratio: f/6.67
Visual Limiting Star Magnitude: 12.3
Resolution: 1.45 arc seconds
Main tube outer diameter: 90mm (tube ring size)
Accessories: a pair of tube rings and dovetail bar
Net weight: 3.40kg (excluding tube rings and dovetail plate)
Total length of telescope (with extended lens shade): 550mm
Total length of telescope (with retracted lens shade): 500mm