Price: $1999 (smaller FRA300 available for $1199)
What is an astrograph?
The Askar FRA500 (Flat field Refractive Astrographs) is a top-of-the-line refractor telescope that is specifically designed for intermediate and advanced level astronomy enthusiasts. As the name implies, astrographs are designed specifically for astrophotography. The telescope has a 90 mm aperture and a focal length of 500mm resulting in a fast 5.6 focal ratio, which makes it a powerful tool for observing celestial objects with remarkable clarity and sharpness. An optional focal reducer brings the focal ratio down to 3.9 for even faster imaging, while still covering a full frame sensor.
What makes the FRA500 special?
One of the unique features of the Askar is the 5 lens Petzval design. The front 3 lenses are designed for color correction. The other 2 lenses are near the focuser and help reduce field curvature and distortions, providing a flat and sharp field of view across the entire very large 55 mm image circle. This is particularly useful for astrophotography as it eliminates the need for additional accessories that can be cumbersome and expensive.
Additionally, it is equipped with a large 3.5 inch two-speed focuser that allows for precise focusing, which is crucial when observing objects in space. An included dew shield helps to reduce dew formation during long image sessions.
Another notable aspect of the Askar FRA500 is its exceptional optics that are made of high-quality materials and coated with multiple layers of anti-reflective coatings to improve light transmission and reduce glare. This results in images that are clear, bright, and have a high level of contrast, making it easier to discern details and features of celestial objects.
Specs:
- Aperture: 90 mm
- Focal length: 500mm
- Focal ratio: f/5.6
- Optical design: Quintuplet Petzval configuration Apochromatic refractor
- Optics material: Extra-low dispersion (ED) glass
- Focuser: Large 3.5 inch two-speed Crayford-style focuser with 10:1 microfocusing knob
- Weight: Telescope tube 4 kg
- Dimensions: Telescope tube 410 mm (452 mm with dew shield fully extended
- Image circle 55mm
- Conical adapter: M48 x 0.75
What’s Included
- FRA 500 optical tube assembly (OTA)
- Pair of tube rings
- Handle
- 300 mm Losmandy dovetail plate
- Conical extender
- Instruction manual
Pros
- Petzval design eliminates need for field flattener
- Very large image circle covers entire full frame sensor with no coma
- Integrated lens design means no back focus calculations
- Compact design is excellent for portable setups
- Very high quality for reasonable price
- Optional FRA 72RD focal reducer makes for even faster f/3.9
Cons
Optional focal reducer improves speed at the expense of image circle
Why you should consider the FRA500
Overall, the Askar FRA500 is a premium-grade telescope that is well worth the investment for serious astronomy enthusiasts who are interested in both visual observation and astrophotography. While it may be pricier than some other options on the market, its advanced features and superior optics make it an excellent choice for those who want the best viewing experience possible. For intermediate or less experienced imagers, setup is easier than with a refractor that requires a separate field flattener. This fantastic astrograph is also available in a smaller version, the FRA400 for $1199 with 72 mm aperture. If you want something a little bigger, consider the Askar 107PHQ F/7 Quadruplet Flat Field Astrograph for $2495 with a 107 mm aperture.