Askar 71F 71mm f/6.9 Flat-Field Quadruplet APO Refractor

A 3kg flat-field refractor for wide nebula fields, travel and quick looks

The Askar 71F Flat-Field is a 71mm f/6.9 air-spaced quadruplet APO refractor with one ED element and a rear lens group that flattens the field for full-frame sensors. It has a retractable dew shield, a dual-speed 2.4" rack-and-pinion focuser with 1:10 fine focus and 50mm of travel, a 360° rotator with scale, a handle with a finder base slot plus two more finder bases at the focuser, and a 230mm Vixen-style plate with 1/4" and 3/8" threaded holes. It's a smart first imaging refractor and an easy companion for camping trips and dark-site weekends.

Key specs: 71mm aperture · 490mm focal length · f/6.9 · quadruplet air-spaced APO with 1 ED element · 44mm image circle, no flattener needed · 2.4" rack-and-pinion focuser, 1:10 fine focus, 50mm travel · 3.0kg (6.6lb) with rings, handle and plate

What you can image and see

• Large nebulae: the North America and Pelican Nebulae, the Heart Nebula, the Rosette Nebula, the California Nebula's brightest part, the Crescent Nebula region in Cygnus and dark nebulae like Barnard 175 (Wolf's Cave).
• Winter showpieces: the Orion Nebula with the Running Man, the Horsehead and Flame Nebulae, and the Pleiades.
• Galaxies: the core of the Andromeda Galaxy, the Triangulum Galaxy (M33), M81 and M82 together, and the Whirlpool Galaxy as a small but detailed target.
• At the eyepiece: wide views of star clusters and the Milky Way, the Moon, Saturn's rings and Jupiter's moons at modest power, and birds and landscapes in daylight.

Fields of view at 490mm: 4.21° × 2.81° with a full-frame sensor, 2.75° × 1.84° with an APS-C camera such as the ASI2600MC Pro (1.58″ per pixel), and 1.32° × 1.32° with the ASI533MC Pro.

How it works

Imaging: the included photographic extension tubes thread onto the focuser and end in an M54 × 0.75 or M48 × 0.75 male thread, with a 2" filter thread built in. Thanks to the 50mm of focuser travel, the sensor can sit 32.5 to 82.5mm behind the M48 thread (50.5 to 100.5mm behind the M54 thread). A camera at the standard 55mm, a filter drawer or an off-axis guider all reach focus without exact spacing.

Visual: remove the camera adapters and use the visual adapter with a diagonal and eyepiece. A 32mm eyepiece gives about 15x and a wide field; an 8mm gives about 61x.

Autofocus: remove the coarse focus knob and mount an electronic focuser on the focuser's bracket holes with a 6mm flexible coupling. Askar's diagrams show the ZWO EAF, Pegasus FocusCube 3, QHYCCD Q-Focuser, ToupTek, iOptron iEAF and Astroasis Oasis focusers fitted.

What to add for the best results

• A mount (required for imaging): the ZWO AM5N with TC40 tripod carries 15kg (33lb) without a counterweight, plenty for the 71F now and a bigger telescope later. Ask us about lighter mounts for travel.
• A camera: the ZWO ASI2600MC Air with built-in ASIAIR and guider, the ASI2600MC Pro, or the ASI533MC Pro for a square 1.3° field.
• Guiding: the Askar 32mm f/4 guide scope on a finder base with an ASI120MM Mini.
• Autofocus: the ZWO EAFN or EAF Pro.
• Filters: a 2" Askar Colour Magic C1 (Hα + OIII) threads into the extension tube; add the C2 (SII + OIII) for bicolor images.
• For visual use: a diagonal such as the Celestron 2" dielectric star diagonal and eyepieces from our eyepiece collection.

Askar F-series comparison

All five share the same 44mm full-frame image circle and self-flattened quadruplet design. See all Askar telescopes.

What's in the box

• Askar 71F Flat-Field optical tube with retractable dew shield
• Pair of tube rings with handle
• 230mm Vixen-style dovetail plate
• Set of photographic adapters (extension tubes with M54 and M48 threads and a 2" filter thread)
• Visual adapter

A mount, camera, diagonal, eyepieces and finder are sold separately.

Askar 71F FAQ

Is the 71F good for beginners?

Yes. Short focal length is forgiving of tracking errors, there's no flattener spacing to get right, and it's light enough for a modest mount. Visually it needs no collimation.

71F or 91F?

The 71F is 1.5kg lighter and frames a wider 2.75° × 1.84° on APS-C, better for the biggest nebulae and for travel. The 91F has 64% more aperture area and 609mm of focal length for smaller targets and brighter visual views.

71F or 60F?

They are close in size: the 60F is 79mm shorter and a little lighter, with a wider 3.30° × 2.20° APS-C field. The 71F collects 40% more light, a real help for visual use and shorter exposures.

Can I see Saturn and Jupiter with it?

Yes, at modest power: Saturn's rings and Jupiter's belts and moons show at 60–100x. For close-up planetary detail, a larger aperture like the 111F does more.

Can I use it as a camera telephoto lens?

Yes. With an M48 T-ring for your camera, such as the Sony E or Canon EOS R version, it becomes a 490mm f/6.9 telephoto for birds, wildlife and the Moon.

Specifications