Askar 103APO f/6.8 Triplet

A 103mm Triplet APO with 1x ED Glass

At the core of the Askar 103APO is an air-spaced triplet apochromatic objective lens, which includes one element of Extra-low Dispersion (ED) glass. Budget astrographs typically use a doublet, while the 103APO uses a triplet plus an ED element to further enhance image quality; APO designs use multiple elements to correct chromatic aberration for better detail and color accuracy.

The 103mm aperture gives an inherent advantage in light-gathering power, resolution, brightness and contrast.

f/6.8 Speed at a 700.4mm Focal Length

At 700.4mm a full-frame sensor covers about 2.9 x 2.0 degrees: the bright body of the Andromeda Galaxy (M31) fits, while the North American Nebula (NGC 7000) needs the 0.8x or 0.6x reducer or a mosaic.

3 Optional Correctors for f/6.8, f/5.4, and f/4 Imaging

For flat-field imaging, Askar offers three optional correctors, each supporting a 44mm full-frame image circle. Each has an M84×1 front thread that screws into the 103APO's M84 female thread after the 2-inch and 1.25-inch adapters are removed, plus M54/M48 adapters and a built-in 2-inch filter thread.

• 1.0x Flattener: This triplet keeps f/6.8 and corrects field curvature and coma, for flatter field edges and finer star points. 55mm back focus from the M48 male thread; 0.58kg.
• 0.8x Reducer: This triplet reducer with field flattening gives 560mm at f/5.4 for a wider field and shorter exposures. 55mm back focus; 0.48kg.
• 0.6x Reducer: This quadruplet reducer with field flattening gives 420mm at f/4. It is used with the rear section of the tube removed, and adds an M68 adapter. 55mm back focus; 0.98kg.

3.3" Rack-and-Pinion with 100mm of Travel

The Askar 103APO has a CNC machined dual-speed 3.3-inch rigid rack-and-pinion focuser with a 1:10 fine adjustment and 100mm of travel. Laser-engraved scales in the length and circumference directions help with adjustment and recording.

The rear of the focuser has a big 360° rotator with precise scales and an enlarged locking screw that prevents image shifting during shooting. The focuser is compatible with most motorized focusers, and the manual marks screw positions for an electric focusing bracket.

A 600mm OTA with Full Stray Light Control

The OTA is 600mm with the dew shield contracted and 711mm stretched. The inner walls of the main tube are coated with matting paint and have an internal baffle, and the dew shield is lined with matting felt, which reduces scattering and reflection for better contrast. An enlarged locking screw keeps the dew shield from slipping.

The OTA features two finder bases, one on each side of the focuser. This removes the need for disassembly when moving the finder and adds mounting positions for other accessories. The tube is CNC machined, anodized and spray painted, and each 103APO has its own name ring.

A 290mm Vixen Plate for the 5.5 kg Load

The total weight with rings and plate is 5.5 kg. The tube rings weigh only 750g, open and lock with CNC thumb screws, and have a raised base for accessory room. The handle has a special slot so it can also take a finder base.

The standard Vixen-style dovetail plate is 290mm long with extra hole positions for moving the rings, which makes balancing easier.

Detachable Tube and 2" / 1.25" Adapters for Visual & Binoviewer Use

The 103APO pays great attention to visual quality and easily reaches focus with 1.25-inch or 2-inch diagonals and eyepieces, using the 2-inch and 1.25-inch adapters at the rear.

The tube has a detachable rear (extender) section. With it removed, the 103APO can be used with a binoviewer.