ASKAR FRA500 F/5.6 APO REFRACTOR

The Askar FRA 500 f/5.6 is a professional apochromatic Petzval quintuplet with an aperture of 90mm and a corrected field of 55mm 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 500 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 55mm 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 3.5" 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.

The FRA500 can be used with the ASKAR F/3.9 Reducer for FRA400 & FRA500.

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

Included Items

• Askar FRA500
  
• Tube rings
• Losmandy style dovetail bar
• Handle on the rings
• Conical extender from M86 x 1 to M68 x 1
• Conical extender from M68 x 1 to M54 x 0.75
• Conical extender from M54 x 0.75 to M52 x 0.75
• Adapter from  M52 x 0.75 to M48 x 0.75
• Manual

Downloads

ASKAR FRA500 manual