Askar 120APO f/7 Triplet

120mm f/7 Triplet APO Optics: High-Contrast Imaging with ED Glass

The core of the 120APO is its 120mm air-spaced triplet objective lens. It uses an ED (Extra-low Dispersion) glass element to reduce chromatic aberration. The native 840mm focal length at f/7 gives a useful image scale for mid-sized galaxies such as the Whirlpool Galaxy (M51); at 840mm a full-frame sensor covers about 2.5 x 1.6 degrees.

The Askar APO series uses special optical designs and multiple lens elements to correct chromatic aberration for higher-quality object details and color accuracy, and the 120mm aperture gives an inherent advantage in light-gathering power, resolution, brightness and contrast. Inside, the main tube is coated with matting paint and has an internal baffle, and the dew shield is lined with matting felt.

Dual-Speed Imaging: Native f/7 or Fast f/5.6 with Optional Correctors

A flat field across a large sensor needs a corrector. Askar offers two optional accessories for the 120APO, each supporting a 44mm full-frame image circle.

• 1x Field Flattener: This triplet accessory maintains the native 840mm focal length and f/7 ratio. It corrects field curvature and coma for flatter field edges and finer star points. It weighs 0.76kg.
• 0.8x Reducer/Flattener: This triplet reducer with field flattening brings the focal length to 672mm and the focal ratio to f/5.6, so the same exposure takes about 64% of the time needed at f/7. It weighs 0.75kg and comes with M68, M54 and M48 adapters.

Both screw into the focuser's M84 female thread in place of the 2-inch and 1.25-inch adapters, are used with the extension tube fitted, and have a standard 55mm back focus from the base of the M48 male thread plus a built-in M48×0.75 2-inch filter thread.

3.3-inch Rack & Pinion Focuser: 100mm of Precision Travel

The Askar 120APO is equipped with a CNC-machined 3.3-inch dual-speed rack and pinion rigid focuser with 100mm of travel, which is compatible with most motorized focusers on the market. It has a 1:10 fine adjustment, and laser-engraved scales in the length and circumference directions make settings easy to record.

A 360° rotator is integrated into the focuser assembly, allowing you to frame your target without rotating the telescope. The rotator has precise scales for adjusting and saving rotation angles, and an enlarged locking screw that prevents image shifting during shooting. The manual marks the screw positions for an electric focusing bracket.

A 6.5 kg Imaging Platform Engineered for Field Use

The 120APO is light and compact at a gross weight of 6.5 kg with rings and plate, and suitable for outdoor shooting. The retractable dew shield, held by an enlarged locking screw that prevents slipping, changes the total length from 804mm to 722mm. The standard Vixen dovetail plate is extended to 290mm with extra screw holes, which makes balancing easier; a Losmandy plate is also sold separately.

Ergonomic details enhance its usability. The tube rings weigh only 780g, have heightened bases and CNC thumb screws for opening and locking without tools. The handle is extended by 60mm and has a slot that works as a finder base, and two finder bases sit on both sides of the focuser for extra accessories.

Binoviewer-Ready Design with 2-inch and 1.25-inch Adapters

The Askar 120APO comes with 2-inch and 1.25-inch adapters, and it reaches focus easily with 1.25" or 2" diagonals and various eyepieces. Its main tube is segmented: with the extension tube fitted it takes a diagonal or the correctors, and with the extension tube removed it can be used with a binoviewer. The manual shows how to unscrew the focuser and the rear section of the tube.

This mechanical flexibility makes the 120APO a versatile telescope for both deep-sky and planetary observation. The triplet objective holds up at higher magnification on Jupiter and Saturn, and the 120mm aperture gives bright views of star clusters and nebulae.

Askar 120APO vs. 103APO: The Advantage of a 120mm Aperture

The 120APO's aperture area is 36% larger than the 103APO's. More aperture means:

• Brighter Images: More light, and a limiting magnitude of 12.2 for the 120APO.
• Higher Resolution: The theoretical resolution limit improves, so closer double stars can be split.