The Askar 71F is a 71-mm f/6.9 flat-field quadruplet astrograph. It features a built-in field flattener, a 44-mm image circle (full frame), and weighs 2.5 kg. No need to buy an optional field flattener: just plug in the camera and it works. At CHF 599 (tax included) in our store, it’s the most compact of the Askar flat-field models for portable deep-sky photography.

All the info at a glance

• Optics: air-gap quadruplet, APO with 1 ED element
• Opening: 71 mm
• Focal length: 490 mm, f/6.9
• Field flattener: built-in, 44 mm image circle (full frame)
• Focusing system: 1:10 rack-and-pinion, 50 mm travel
• Weight: 2.5 kg (tube), 3.0 kg with clamps and tray
• Length: 372.5 mm (defogger retracted)
• Tabletop: Vixen 230 mm included
• Connectors: M64, M54, M48 (with M48 filter thread)
• 0.75x reducer: optional, for f/5.2
• Price: CHF 599, including tax (Swiss VAT included)
• Availability: In stock in our store
• Warranty: 2 years

Flat-field quadrupole: the flattener is inside

The 71F is a quadruplet: four lenses, one of which is made of extra-low dispersion (ED) glass. The first group corrects chromatic aberration, while the second group (the field flattener) corrects field curvature. The result: a flat field across a 44 mm image circle—enough to cover full-frame (36×24 mm) with room to spare. No need to buy an external flattener or calculate optical extension.

Compare this to a conventional triplet: the triplet corrects chromatic aberration but leaves the curvature. An external flattener (CHF ~200) must be added to achieve a flat field. The quadruplet does both at once. It’s simpler, and it works.

71 mm at f/6.9: versatile and portable

With a focal length of 490 mm and an aperture of f/6.9, the 71F is a versatile astrograph. It’s not as fast as an f/5, but it’s fast enough for wide-field deep-sky photography: M31 Andromeda, M42 Orion, the Pleiades, and the Milky Way in wide-field views. Exposures ranging from 60 to 180 seconds are sufficient with a modern camera.

The 0.75x reducer is available as an option. It converts the 71F to f/5.2 (367.5 mm focal length) for an even wider field of view. At f/5.2, short exposures capture large, expansive subjects.

Weighing 2.5 kg and measuring 372.5 mm long, the 71F fits in a backpack. It’s the astrograph you take with you on trips, under a truly dark sky, far from the city. When mounted on a lightweight mount (AM3N, Wave 100i, Star Adventurer GTi), it doesn’t add any extra weight.

The Askar F Series: 60F, 71F, 91F, 111F, 131F

The 71F is part of Askar’s F (Flat-Field) series: 60F, 71F, 91F, 111F, 131F. All are flat-field quadruplets with a built-in flattener and a 44-mm image circle. The difference lies in the aperture and weight:

• 60F : 60 mm, the most compact, for travel.
• 71F : 71 mm, the all-arounder. The best balance of portability and performance.
• 91F : 91 mm, more light for faint objects.
• 111F : 111 mm, the high-performance wide-angle lens.
• 131F : 131 mm, the large flat-field astrograph.

The 71F is the perfect compromise: wide enough for deep-sky photography, light enough for travel. Weighing just 2.5 kg, it’s the astrograph you’ll reach for without hesitation.

Which mount should I use for the 71F?

Weighing 2.5 kg per tube, or 3 kg with clamps and base, the 71F can be mounted on:

• AM3N : harmonic drive, 12 kg payload. Ideal with plenty of headroom.
• Wave 100i : harmonic drive, 10 kg payload. Compact.
• Star Adventurer GTi : For traveling light, the payload is 5 kg. Just enough.
• HEQ5 : Classic equatorial mount, 13 kg payload. Extremely stable.

Why shop at Deep Space Astronomy?

We're not just a retailer. We test, advise, and provide support.

• Personalized Advice : We can help you choose between the 60F, 71F, and 91F models based on your mount and your targets. Contact us by phone, WhatsApp, or schedule an appointment in Nyon.
• After-Sales Support : Do you have a question about the flattener, optical alignment, or image processing? We're here to help.
• 14-Day Return Policy : Not satisfied? Return the product within 14 days.
• Secure payment : Twint, credit card, invoice, Apple Pay, Bitcoin. Pay in 3 or 4 installments with no fees.
• Free shipping in Switzerland Starting at CHF 200. Free pickup in Nyon.

L’The Askar 71F is priced at CHF 599, including tax in our store. Be sure to check out the Askar line and the other flat-field astrographs in the F series.

Sources

This article is based on Askar’s official specifications (via High Point Scientific, First Light Optics, and Mile High Astro, 2026) and on the product listing in our store. In-store price: CHF 599 (including tax).

CBurkhalter