Askar 203APO Triplet Refractor

Askar 203APO Triplet Refractor

The Askar 203APO is an optical tube with a 203 mm aperture, a 1421 mm focal length, and a native focal ratio of f/7.
It has an effective aperture area 20% larger than that of the 185APO and can reach a limiting magnitude of 13.3.

Its large aperture naturally provides advantages in light-gathering power, resolution, brightness, and contrast, allowing more light to be collected and revealing finer details as well as brighter objects in images.

The Askar 203APO features an air-spaced triplet APO optical design that includes one ED glass element.

The Askar APO series uses specialized optical designs and multiple lens elements to correct chromatic aberration, ensuring more precise details and improved color accuracy.

In a refractor’s optical structure, increasing the number of lenses and optimizing their combinations can improve chromatic aberration correction, although this also increases manufacturing costs and design complexity.

ED glass, or extra-low dispersion glass, is a type of optical glass specifically engineered to reduce chromatic aberration.

As a large-aperture, long focal ratio optical tube, the Askar 203APO was designed with portability in mind. Thanks to its retractable optical tube, its minimum length is only 1145 mm. Its net weight is 14.9 kg, and its gross weight is 23.5 kg (including the handle, tube rings, and dovetail plate).

Each Askar 203APO is equipped with a unique identification ring. The retractable dew shield, combined with enlarged locking screws, ensures convenient handling.

The 203APO’s tube rings feature a reinforced three-point structure for enhanced strength. The thumb screws allow easy opening and locking, while the raised base provides additional space.

The Askar 203APO includes an extended 402 mm handle with a dedicated slot, which can also serve as a mounting base for a finder.

The dovetail plate of the Askar 203APO follows the Losmandy standard, making it compatible with most equatorial mounts and bases available. It features multiple mounting holes for easier adjustments, and its extended 500 mm length improves balance on the mount.

It is important to note that the rear tube of the Askar 203APO features an integrated retractable design. This reinforced structure ensures optimal stability and maintains the alignment of the optical axis when the tube is extended, thereby preserving image quality. The retractable section is equipped with a rudder-type locking ring, allowing easy and efficient tightening or loosening.

When the tube is extended, the 203APO can be used with a diagonal and an eyepiece for observation. When it is retracted, the Askar 203APO can be paired with a binoviewer for visual observation.

Regarding the focuser, the Askar 203APO is equipped with a rigid 3.5-inch dual-speed rack-and-pinion focuser, compatible with most motorized focusers on the market. A high-precision scale is printed along the 100 mm focusing travel. The focuser barrel is fully CNC-machined, with an internal anti-reflective design and matte coating to effectively eliminate stray light.

Two finder bases are integrated on each side of the focuser, avoiding the need for disassembly when changing the finder’s position and providing additional mounting points for other astronomical accessories.

The rear of the focuser includes a large, high-precision 360° rotator with engraved scales for easy adjustment and angle retention, ensuring accurate rotation. An enlarged locking screw ensures secure holding, even under heavy loads.

For visual observation, the rear focuser interface comes with a 1.25"/2" adapter, allowing easy focusing with 1.25" or 2" diagonals or eyepieces. Thanks to the retractable tube, a binoviewer can also be used.

The entire Askar 203APO optical tube is manufactured using high-quality CNC machining with anodized and surface-paint treatments. The orange accents on the ivory tube add an elegant and modern touch.

A dedicated reducer and flattener for the 203APO will be released later, offering even more possibilities for this instrument.

TECHNICAL DATA SHEET

• Aperture: 203 mm
• Effective aperture area 20 percent larger than the 185APO
• Limiting magnitude: 13.3
• Focal length: 1421 mm
• Native focal ratio: f/7
• Optical design: air-spaced APO triplet
• Optical element: one low-dispersion ED glass element
• Advanced chromatic aberration correction through multi-element design
• Improved colour fidelity, contrast and resolution
• Integrated retractable optical tube
• Minimum tube length: 1145 mm
• Total length with dew shield extended: 1335 mm
• Rear retractable tube length: 150 mm
• Optical tube weight: 18.5 kg
• Gross weight with handle, tube rings and dovetail: 23.5 kg
• Design optimised for portability despite the large aperture
• Unique identification ring on each unit
• Retractable dew shield with enlarged locking screws
• Reinforced tube rings with three-point structure
• Thumb screws for easy opening and locking
• Raised tube ring base providing additional clearance
• Handle length: 402 mm
• Handle with slot usable as a finder mount
• Losmandy standard dovetail plate
• Dovetail length: 500 mm
• Multiple mounting points for precise balancing
• Reinforced rear structure maintaining optical axis alignment
• Rudder-type locking ring on the retractable rear tube
• Use with diagonal and eyepiece in extended position
• Binoviewer compatibility in retracted position
• Rigid 3.5-inch rack-and-pinion focuser
• Dual-speed focusing mechanism
• Compatible with most electronic focus motors on the market
• Focuser travel: 100 mm with high-precision scale
• Focuser tube CNC-machined with internal anti-reflective treatment
• Matte internal finish to suppress stray light
• Two integrated finder bases on each side of the focuser
• Additional mounting points for astronomical accessories
• Large 360-degree precision rear rotator
• Engraved graduations for precise adjustment and repeatability
• Large locking screw suitable for heavy loads
• Supplied rear visual adapters: 1.25 inch and 2 inch
• Compatibility with 1.25 inch and 2 inch diagonals and eyepieces
• Binoviewer use made possible by the retractable tube
• Optical tube fully CNC-machined
• Anodized finish and surface paint treatment
• Ivory tube with orange accents
• Dedicated reducer and flattener planned for the 203APO
• Standard package contents: 203APO optical tube, tube rings, handle, 500 mm Losmandy dovetail plate, aluminum case, manual