Askar FRA500 90mm f/5.6 Quintuplet APO
Description
- Compact and Portable
- High-Quality Imaging
- Precision Focusing
- Elegant Design
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Sharpstar Optics is proud to introduce the Askar FRA500 astrograph, the latest addition to the well-known FRA family. With a 500mm focal length and a 90mm aperture (f/5.6), the Askar FRA500 is better suited for deep-sky imaging compared to the Askar FRA400. Additionally, its lighter and more compact design makes it an excellent choice for outdoor observation and astrophotography, especially when compared to the Askar FRA600.
The Askar FRA500 carries forward the superior design legacy of the FRA series. It features a quintuplet air-spaced APO optical structure with a “three plus two” Petzval lens combination. The front lens group consists of three lenses, including two ED glass elements, providing excellent aberration correction. The rear group has two lenses separated by a small space, ensuring sharpness across the entire image. This design virtually eliminates any blurry stars at the image edges. The FRA500 supports an impressive 55mm image circle, much larger than the standard 44mm full-frame image circle. Its special back-focus design eliminates the need to calculate confusing back-focus distances or search for the right spacer. All you need to do is focus on keeping your target sharp.
Askar FRA500 is typically a wonderful mix of pragmatism and aesthetics. The astrograph shows smooth lines and a sound layout of components. From the front, the Askar FRA500 has an impressive dew shield decorated with a classic bright-red bezel ring. The total length of FRA500 is 452mm when the dew shield is stretched out and 410mm when contracted back. At the tail end of the astrograph locates a 3.5" massively-built focuser with dual-speed hand knobs (twin knobs for coarse adjustment and one 1:10 fine adjustment knob), which is of great use in real observation or astrophotography. The astrograph wears smooth coating and is evenly finished. The graduation inside of the focuser is quite clear and easily readable. The focuser is tough and solid, and on the left side of it, there is a standard finder base with a silver thumb screw. So the FRA500 can piggyback carry finders, guiders or other potential astronomy accessories. Askar FRA500 comes also with a pair of sought-after tube rings. On the top of the tube rings attached a handle and at the bottom, there is an Askar Losmandy-style dovetail plate. The combination of milk-white main tube and dew shield together with a high-gloss piano-black focuser makes the optical tube assembly calm and deep which is offset by the bright red decorative ring and tube rings.
The Askar FRA500, measuring 410mm in length and weighing around 4kg, is convenient for users to carry and mount on an EQ mount. It's especially suitable for astronomy enthusiasts who often go on long-distance trips or engage in outdoor astrophotography. The Askar FRA500, along with the rest of the FRA family, is well-regarded for its large aperture, fast speed, delicate focusing system, unique optical design, and high-quality imaging results. We hope the Askar FRA500 becomes a loyal companion on your astrophotography journey.
Aperture | 90mm |
Focal Length | 500mm |
Focal Ratio | f/5.6 |
Objective Lens | Quintuplet air-spaced APO (including two ED glass) |
Image Circle | 55mm |
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OTA Weight | 4.1kg |
Total Weight (Including tube ring&dovetail plate) | 5.2kg |
Rear-end thread type | 86x1 |
Conical Adapter | 48x0.75 |
Package items |
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