ASKAR FRA400 F/5.6 APO REFRACTOR
Askar
Apochromatic Petzval quintuplet
2.88 kg
ASKAR FRA400 F/5.6 APO REFRACTOR is backordered and will ship as soon as it is back in stock.
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.
Specifications
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 |
Included Items
- 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
Downloads
ASKAR FRA400 manual |
Gallery