Sharpstar 150 F/2.8 HNT hyperbolic astrograph with aluminium OTA

Sharpstar 150 F/2.8 HNT hyperbolic astrograph with aluminium OTA

Sharpstar presents the 150 F/2.8 HNT AL compact astrograph in the new aluminium tube and with improved mechanics compared to the previous carbon tube version. A reflector with a 150 mm hyperbolic primary mirror open at F/2.8 and a focal length of 420 mm, equipped with a 3-lens field corrector capable of covering an image circle up to 44 mm in diameter, i.e. up to full-frame format (24x36 mm). A wonderful tool for wide-field imaging!

The Sharpstar 150 F/2.8 HNT AL hyperbolic astrograph is a hyperbolic reflector with a 150 mm aperture and a fast focal ratio of F/2.8 capable of supporting a 44 mm full-frame image circle. The stellar performance is excellent.

The primary mirror is made of Pyrex PZ33 type glass. The coefficient of thermal expansion is lower than that of ordinary glass. The multilayer dielectric coating gives the primary mirror a high reflectivity of up to 97%. The minor axis diameter of the secondary mirror is 70 mm, allowing sufficient illumination even for full-frame sensors. The focuser corrector adopts a three-lens design, one of which is composed of low-dispersion ED glass to better correct residual aberrations.

The Sharpstar 150 F/2.8 HNT AL hyperbolic astrograph further improves the stability of the optical axis structure of the primary mirror and features three sets of adjustment screws on the bottom of the objective tube to adjust the angle of the primary mirror.

In addition, the Sharpstar Hyperbolic Astrograph 150 F/2.8 HNT AL improves the secondary mirror beam structure to make it more stable. The entire secondary mirror block is CNC machined.

There is a base on one side of the optical tube to accommodate a finder or a small guide scope.

The pair of rings of the Sharpstar 150 F/2.8 HNT AL astrograph are very robust and durable. Oversized knobs allow the rings to be opened and closed without the need for additional tools.

The focuser of the Sharpstar 150 F/2.8 HNT AL astrograph is also oversized, with a rack-and-pinion mechanism. It is also equipped with a fine focus knob for precision focusing. The travel is 2 cm and the total capacity is around 3 kg. The focuser is compatible with most motorised focusers on the market. At the base, the focuser is rotatable.

Inside the focuser is a three-lens field corrector, one of which is ED. On the top is the M48 threaded adapter and the backfocus is 55 mm.

The astrograph is equipped with a 200 mm long Losmandy lower bar. Above the rings is a handle with a slot, which allows the possible attachment of a small guide scope.

The entire optical tube is made of lightweight aluminium, with CNC-machined parts.

Features

• Optical design: reflector with hyperbolic primary mirror and 3-lens corrector at the focal plane
• Primary mirror: 150 mm
• Secondary mirror: 70 mm
• Mirror substrate: low expansion H-PZ33 borosilicate (like Pyrex) with high-refelctivity dielectric coating (97%)
• Linear obstruction: ~ 46,7% (21,8% area)
• Focal length: 420 mm
• Focal ratio: F/2.8
• OTA length: 450 mm
• Outer tube diameter: 193 mm
• Backfocus: 55 mm from the M48x0.75 threaded adapter (fits M48 rings).
• OTA fully build with light aluminium alloys CNC machined
• 2.5" R&P focuser with micro-pinion assembly and integrated optical corrector (removable).
• Comes with Losmandy dovetail plate, universal finder base, CNC rings and handle.
• Weight: around 4.8 Kg OTA only, 6 Kg complete with rings, dovetail and handle.

Mechanical diagrams

Motor focuser mounting

Sample images

This item is currently out of stock with the manufacturer and we are awaiting further updates. Orders are temporarily suspended.