ASKAR FRA400 F/5.6 APO REFRACTOR
Askar
Apochromatic Petzval quintuplet
72 mm
f/5.6
400 mm
2.88 kg
ASKAR FRA400 F/5.6 APO REFRACTOR is backordered and will ship as soon as it is back in stock.
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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.
| 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, M48 x 0.75 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.
Orion Nebula by Mark Button | Askar FRA400, Modded Nikon D7500, SkyWatcher Star Adventurer.
Customer Reviews
The guys at Testar answered many of my emails quickly and guided me through my options. I can't be more happy with their service.
I used the telescope itself a couple of nights and the quality was really good, I've been using camera tele lens before and you can definitely see the difference.
My only dark spot was DHL, who messed up with my shipping and ended up taking 3 more weeks than expected... but again, that was DHL's fault, the telescope and Testar are 5 stars!
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.
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.
