Astronomy Specialist



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The Askar FRA 400 f/5.6 is a professional apochromatic Petzval quintuplet with an aperture of 72mm and a corrected field of 44mm in diameter.

The lenses are assembled in two groups: an air-spaced triplet on the front and a  correcting doublet towards the focus. The objective lens includes two Extra Low  Dispersion glass for a superb chromatic correction.

Differently from standard ED refractors, the Askar 400 features a Petzval design that does not require to set the sensor to a specific distance to the last lens. That leaves the freedom to use any filter wheel, any off-axis guider or accessory without any worry to calculate the correct distance from the flattener. 

With a large 44mm fully corrected image circle and a focal ratio of f/5.6, this is the perfect astrograph for the advanced astrophotographer. The large rack and pinion 3" focuser has a high payload capacity, it can be rotated 360° to perfectly frame the subject and it has a reduction gear of 10:1 for precise focusing.

All the lenses are fully multi-coated and the tube is internally blackened to reduce reflections and absorb stray light. The tube is made of aluminium, the rack and pinion focusing mechanism of brass and the mechanical components are engineered to provide the best rigidity, performance and durability.

Every Askar telescope is inspected on the optical bench by Testar and is guaranteed against defects. To ensure optimal performance, we test every single telescope on an optical bench, using an artificial star in autocollimation. This test can easily reveal the presence of optical defects such as spherical aberration, astigmatism, zonal errors, coma or optical elements out of collimation. The light from the artificial star travels from the eyepiece holder through the lenses and it gets reflected by a high quality Zerodur flat mirror with a correction peak-to-valley of λ/20. Then, the light travels back through the lenses, gets divided by a beam splitter, then is magnified by a high quality Barlow and finally analyzed with an eyepiece and a camera. This is a test in double pass and any optical aberration gets magnified twice and therefore optical errors can be easily detected. 


Askar FRA 400 Review

 Askar FRA 400 tested on optical bench




Optical design

Apochromatic Quintuplet dual ED air spaced

Objective diameter

72 mm

Focal length


Focal ratio


Resolving power

1.66 arc second

Stellar limiting magnitude


Max. magnification

144 x

Light gathering power

106 times the human eye

Mount attachment

Vixen style bar


Rack & pinion dual speed (10:1) 3" diameter

Camera connection

M68x1 male thread, 2" ; 1.25" 


140 mm

Tube weight

2.88 kg (including tube rings and dovetail bar)

Tube length

317 mm

Tube diameter

90 mm

Dew shield diameter

100 mm








  • Askar 400
  • 90 mm tube rings
  • 150 mm Vixen style dovetail bar
  • Handle on the rings
  • Adapter to 2" and 1.25"
  • Adapter from M68 to M54 male
  • Adapter from M54 to M48 male


M20 & M8 by Mark Button | Askar FRA400, Modded Nikon D7500, ZWO Duo-Band filter


M20 & M8 by Mark Button | Askar FRA400, Modded Nikon D7500, ZWO Duo-Band filter.

Customer Reviews

Based on 1 review
Lonosham Observatory
Amazing quality widefield DSO imaging

This scope provides excellent image quality, right out of the box, and was incredibly easy to set up and use with common equipment.

Back focus is generous, and the included adaptor allowed direct connection to a ZWO 8x1.25" electronic filter wheel and ZWO ASI 1600MM camera with a single 1" M42-M42 extender. Imaging was up and running on the first night after purchase, unheard of in this age of custom adaptors and caliper-precision back focus calculations.

The draw is a generous 50mm, and the 10:1 focuser is simple to use, and although there is a little backlash, it is very manageable and quickly overcome and becomes second nature.

The imaging field is totally flat for a 4/3" sensor like the ZWO ASI 1600MM has. Use of camera T-rings allow mirrorless cameras quick access to a perfectly flat image.

The build quality is great, solid steel tube and secure rings for mounting. The integrated dew shield does have a little play and may slide with heavy use, but a jury-rigged tube or a little grease resolves that quickly.

This is an excellent 400mm scope with amazing imaging quality.

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