Approchromatic Refractor ASKAR 203APO

The Askar 203APO is an OTA with an aperture of 203 mm, a focal length of 1421 mm and a native focal ratio of F7.

The Askar 203APO has a 20% larger effective aperture area than the 185APO, and the limiting magnitude can reach 13.3.

The large aperture provides an inherent advantage in terms of light gathering power, resolution, brightness and contrast, allowing the photographer to capture more light and present more detail and brighter subjects in the image.

The Askar 203APO adopts an air-spaced triple APO lens design, which includes a piece of ED glass.

The Askar APO series employs special optical designs and multiple lens elements to correct chromatic aberration, naturally providing higher quality object details and color accuracy.

In the refractor element structure, increasing the number of lens elements and designing lens combinations can effectively improve chromatic aberration correction. However, this also means increased production costs and design complexity.

ED glass, also known as low dispersion glass, is a type of optical glass specifically designed to reduce chromatic aberration.

As a large aperture, long focal ratio OTA, the Askar 203APO was designed with portability in mind. Due to the retractable lens tube design, the shortest overall length is only 1145 mm, the net weight is 14.9 kg and the gross weight is 23.5 kg (including the handle, tube ring and dovetail plate).

Each part of the Askar 203APO is equipped with a unique name ring for identification. The retractable design of the spray shield, along with the enlarged locking screws, provides comfortable use.

The 203APO 's tube ring has an improved triplet design, which is rugged. The thumbscrews allow easy opening and locking of the tubular rings. In addition, the base of the tube rings is taller, which provides more space.

The Askar 203APO has a 402 mm extended grip with a special slot design, making it also a base for installing a scope.

The dovetail plate of the Askar 203APO is the standard dovetail plate from Losmandy, which is compatible with most equatorial mounts and bases on the market. The dovetail plate is designed with multiple holes, making it easy to adjust the position. The length of the dovetail plate has been extended to 500mm, which is more convenient for balancing the mount.

It is worth noting that the rear lens tube of the Askar 203APO has an integrated retractable design. We strengthen the overall stability and ensure that the optical axis will not be affected when the lens tube is stretched, thus guaranteeing image quality. The retractable part also features a rudder-type locking ring for easy loosening or tightening.

When the objective tube is stretched, the 203APO can be connected to a diagonal and eyepiece for observation. When the objective tube is contracted, the Askar 203APO can be used with a binocular for visual observation.

As for the focuser, the Askar 203APO is equipped with a large 3.5-inch dual-speed rigid rack and pinion rigid focuser, which can be compatible with most motorized focusers on the market. There is a high precision scale printed on the 100 mm focusing travel. The entire focuser barrel is CNC machined with an internal anti-reflective design and matte paint, which provides additional measures to eliminate stray light.

There are two finder bases on both sides of the focuser, which not only eliminates the need to disassemble the focuser to change the finder position, but also provides additional mounting positions for other astronomical accessories.

The rear of the focuser incorporates a large, high-precision 360° rotator, along with precise scales for convenient adjustment and storage of rotation angles, allowing for precise rotation. It is also equipped with an enlarged rotator locking screw that can be easily fixed even under high loads.

As for visual observation, the focuser interface on the back comes with a 1.25"/2"， adapter so the 203APO can easily achieve focus when connected to 1.25" or 2" diagonals or multiple eyepieces. Due to the retractable design of the lens tube, it can also be connected to a binoviewer for visual observation.

The entire tube of the Askar 203APO is manufactured by high quality CNC machining with anodizing and surface spray paint treatments. Orange accents on the ivory white tube add a bright, eye-catching touch, presenting an overall sleek and stylish appearance.

Technical Features

Aperture size: 203 mm

Focal length: 1421 mm

Focal ratio: f/7

Lens: Triplet APO lens with airgap (including ED glass)

Total length: 1145mm(when the dew shield is contracted)

1335mm(when the dew shield is stretched)

Rear retractable lens tube length: 150mm

OTA weight: 18.5kg

Gross weight（including the tube ring and dovetail plate: 23.5 kg

Rear thread type: 2"/1.25" sight adapters

Standard package items: one OTA 203APO, one set of tube rings, one handle, one dovetail plate Askar 500mm Losmandy, one aluminum case，one manual.

Product size diagram

Instructions for use of 203APO retractable objective tube (for ocular observation, 1.0x flattener and 0.8x reducer)

Locking screw position diagram

203APO EAF（optional） Installation

Optical path diagram