Askar 103 APO F/6.8 Triplet Refractor

In astrographic telescopes, aperture size has a significant impact on observability and image quality. The 103mm aperture gives the telescope an inherent advantage in light-gathering power, resolution, brightness and contrast, allowing the photographer to collect more light and present more detail and brighter objects in the image.

The Askar 103APO adopts an air-spaced triplet APO lens design, which includes an extra low dispersion (ED) glass element.

An APO (Apochromatic) telescope is a type of telescope with the ability to correct chromatic aberration. Chromatic aberration is a common optical aberration that causes colored edges or blurring around the edges of objects in an image. Other telescopes have relatively simple optical designs and are prone to chromatic aberration, especially at high magnifications or in observations where color accuracy is required. However, APO telescopes employ special optical designs and multiple lens elements to correct chromatic aberration, naturally providing superior object detail and color accuracy.

In the structure of refractive elements, increasing the number of lens elements and designing lens combinations can effectively improve the correction of chromatic aberration. However, this also leads to increased manufacturing costs and design complexity.

ED glass, also known as low dispersion glass, is a type of optical glass specially designed to reduce chromatic aberration. Chromatic aberration occurs because light of different wavelengths refracts differently when passing through a lens, causing color separation and a decrease in image quality. ED glass has special optical properties that help reduce stray light and effectively minimize chromatic aberration.

The Askar 103APO not only adopts a triplet lens design (while cheap astrographs on the market typically use doublets), but also has ED glass to further improve image quality.

In addition to the carefully designed lens, every aspect of the Askar 103APO is dedicated to providing a better shooting experience for users.

The entire interior of the Askar 103APO sunshade is lined with matte felt, while the internal walls of the main tube are coated with matte paint and provided with internal whiskers. This effectively reduces the scattering and reflection of light within the OTA, thus improving the brightness, contrast and resolution of the observed targets.

Each Askar 103APO example comes with a unique name ring for identification, making each Askar 103APO telescope exclusive to its owner.

The retractable design of the sun visor, together with the enlarged locking screws, offers convenient use. The sunshade serves to protect the lens from the impact of external and internal light, while ensuring the protection of the lens itself.

On the Askar 103APO, there are a total of two seeker bases. Each side of the focuser is equipped with a finder base. Many users have expressed concerns about limited space for installing additional astronomical accessories during use. To address this issue, we have specifically placed finder bases on both sides of the focuser. This not only eliminates the need for disassembly when changing the position of the finderscope, but also provides additional mounting locations for other astronomical accessories.

The handle of the Askar 103APO has a special slotted design, making it also a base for installing a finder scope. The handle itself is sturdy and durable.

The overall design of the tube rings is lightweight, with a total weight of just 750g. The thumb screw of the tube ring allows for easy opening and closing. At the same time, the raised base creates more space to accommodate astronomical accessories. In daily use, the comfort of each step is taken into account.

The dovetail plate is the standard Vixen plate, compatible with most equatorial mounts and bases available on the market. We also made extensions and additional hole position designs, with the length up to 290mm, making it more convenient for balancing on equatorial mounting. With the slot on the handle, the spacing between the tube rings can be adjusted as desired. Additionally, a Losmandy dovetail plate is also available for purchase, for use with various equatorial mounts.

The detachable main tube design makes it possible to reduce the focal ratio from native 6.8 to 4. It can also be used for binoviewer observations.

The Askar 103APO offers three optional advanced accessories: a 1x flattener, a 0.8x reducer, and a 0.6x focal reducer. All three accessories feature 2" filter threads for direct installation of filters. Additionally, they come with M54/M48 adapters, and the 0.6x reducer includes an additional M68 adapter ring for convenient connections.

The 1x flattener does not change the focal ratio of the telescope itself. After connecting with the Askar 103APO, it still maintains a focal ratio of 6.8. The flattener corrects field curvature and coma, resulting in flatter field edges and finer star points.

The 0.8x reducer can bring the focal ratio of the Askar 103APO to F5.4. This is a standard leveler with field flattening capabilities. A shorter focal ratio allows the OTA to have a wider field of view and faster exposure times, making it suitable for capturing large areas of nebulae, star clusters and faint, fast-moving celestial objects.

The 0.6x reducer can bring the focal ratio of the Askar 103APO to F4, also providing field flattening. The Askar 103APO adopts a detachable tube design, where the back of the tube can be removed when using the 0.6x flattener, allowing the telescope to have the length needed to achieve an F4 focal ratio.

Thanks to the detachable lens tube design, the Askar 103APO can be used for observations with a binoviewer.

Specifications

• Opening size: 103mm
• Focal length: 700.4mm
• Focal ratio: f/6.8
• Objective lens: Air-spaced APO triplet (with an ED glass)
• Total length: 600 mm (with contracted sun visor), 711 mm (with extended sun visor)
• OTA weight: 4.75 kg
• Gross weight (including tube rings and dovetail plate): 5.5 kg
• Rear Thread Type: 2"/1.25" Visual Adapters
• Items included in the standard package: One OTA 103APO, one pair of tube rings, one handle, one Vixen 290mm dovetail plate, one manual, one Oxford cloth case