Askar FRA500 90mm: The reference apochromatic refractor for astrophotography
The Askar FRA500 90mm is currently the best-selling model in the quintuplet apochromatic series, designed to deliver optimal performance for astrophotography. Thanks to its five-element air-spaced optical design, it provides a flat field up to 44mm diagonal without the need for additional flatteners or reducers.
Advanced optics for images free of chromatic aberration
The FPL-53 quintuplet apochromatic lens, built with high-quality optical elements from Ohara (Made in Japan), ensures exceptional color correction. The objective features an air-spaced triplet, with a central element made of Super APO-FPL53, delivering high-contrast, aberration-free images even at maximum magnification.
Precision mechanics and professional focuser
The FRA500 is equipped with a 3.5” Rack & Pinion focuser with an integrated 360° rotator, designed to support heavy loads without flexing. The 1:10 reduction gear allows for ultra-precise focusing, making it ideal for long-exposure astrophotography.
Technical specifications
- Aperture: 90 mm
- Focal length: 500 mm
- Focal ratio: f/5.6
- Objective: Quintuplet APO with two ED elements
- Image circle: 55 mm
- Backfocus: 158 mm (M48×0.75 thread) / 85 mm (M86×1 thread)
- Total length: 452 mm (410 mm with retracted dew shield)
- Net weight: 4.1 kg
- Gross weight: 5.2 kg
- Rear threads: M86×1 / M48×0.75
- Included accessories: FRA500 OTA, tube rings, handle, Losmandy dovetail plate, conical extender, manual
The Askar FRA500 is the perfect choice for astronomers looking for a high-quality apochromatic refractor with excellent optics and robust mechanics, all at an unbeatable price-performance ratio.