Sharpstar Optics proudly presents the Askar FRA500, the newest member of the renowned FRA-family. With a 500mm focal length and a 90mm aperture (f/5.6), the FRA500 is specifically designed for deep-sky imaging, offering better capabilities than the smaller FRA400 while being more lightweight and portable than the FRA600. This makes it an ideal choice for both outdoor observation and astrophotography.
The Askar FRA500 inherits the superior design legacy of the FRA-series, featuring a quintuplet air-spaced APO optical structure. This "three plus two" Petzval lens combination includes a front lens group with three lenses, two of which are ED glass, ensuring excellent aberration correction. The posterior group, composed of two lenses separated by a small space, provides sharpness across the entire image, virtually eliminating blurry stars at the edges. The FRA500 supports a 55mm image circle, which is significantly larger than the standard 44mm full-frame image circle. Its special back-focus design simplifies focusing, allowing you to concentrate solely on achieving perfect focus on your target.
Aesthetically, the Askar FRA500 is a blend of practicality and elegance. It features smooth lines and a well-organized layout. The dew shield, adorned with a classic bright-red bezel ring, stretches the total length of the FRA500 to 452mm and contracts to 410mm for portability. At the rear, a robust 3.5" focuser with dual-speed hand knobs offers both coarse and fine adjustments, ensuring precise focus for observation or imaging. The focuser includes clear graduations for easy reading, a standard finder base, and a solid build to support additional astronomy accessories.
The Askar FRA500 is equipped with a pair of stylish tube rings, featuring a convenient handle on top and an Askar Losmandy-style dovetail plate at the bottom. The optical tube assembly combines a milk-white main tube and dew shield with a high-gloss piano-black focuser, accented by a bright red decorative ring and tube rings, creating a visually striking yet functional design.
Weighing approximately 4kg and measuring 410mm in length, the Askar FRA500 is portable and easy to mount on an EQ mount, making it perfect for astronomy enthusiasts who travel frequently or engage in outdoor astrophotography. Known for its large aperture, fast speed, precise focusing system, unique optical design, and high-quality imaging results, the Askar FRA500 is poised to be a loyal companion on your astrophotography journey.
Specifications
FRA500 Parameters
Aperture size
90mm
Focal length
500mm
Focal ratio
f/5.6
Objective lens
Quintuplet air-spaced APO (including two ED glass)
Image circle
55mm
Back focus
158mm（from base of M48×0.75 thread on the conical extender to focal plane）
85mm（from base of M86×1 thread on the rotator to focal plane）
Total length
452mm（410mm when the dew shield is contracted）
OTA Weight
4.1kg
Total Weight (Including tube ring&dovetail plate）
5.2kg
Rear-end thread type
86×1
Conical adapter
48×0.75
Package items
An FRA500 OTA, a pair of tube rings, a handle, an Askar Losmandy dovetail plate, a conical extender, a manual
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