Astronomy Specialist

ASKAR FRA400 F/5.6 APO REFRACTOR

$1,999.00

Quantity
- +

 

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.


 

Optical design

Apochromatic Quintuplet dual ED air spaced

Objective diameter

72 mm

Focal length

400

Focal ratio

f/5.6

Resolving power

1.66 arc second

Stellar limiting magnitude

11.3

Max. magnification

144 x

Light gathering power

106 times the human eye

Mount attachment

Vixen style bar

Focuser

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

Camera connection

M68x1 male thread, 2" ; 1.25" 

Backfocus

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

SKU

AS-FRA400

 

 

 

 

 

  • 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

 

 

Horsehead Nebula by Mark Button | Askar FRA400, Modded Nikon D7500, SkyWatcher Star Adventurer.

 

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.

 

 

Orion Nebula by Mark Button | Askar FRA400, Modded Nikon D7500, SkyWatcher Star Adventurer.

Customer Reviews

Based on 2 reviews
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J
John Haunton
Great grab and go scope

I have owned this model for just on a year now. I am very pleased with the results, it was purchased to use in a portable AP setup and with either a ASI294 or mirrorless Olympus. It performs brilliantly with both, the field is flat and there is no colour fringeing I can see. Construction is first class, focuser is solid as a rock and easily automated. Only thing I have added is an extension to the dew shield (to minimise stray light entry when I use it a home). Best scope I have used, lots of fun.

L
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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