CHF 839
In stock with supplier
L'Askar 91F Flat-Field is a top-of-the-range apochromatic refractor designed for astronomers looking for a versatile instrument capable of excelling in both astrophotography and visual observation. With its 91 mm, its focal length of 609 mm and its native focal ratio of f/6.7, It offers an excellent compromise between power, optical quality and transportability.
Thanks to its optical formula self-correcting APO quadruplet, With its ED glass element, the Askar 91F delivers extremely clean, star-fine images even on Full Frame sensors. Its built-in field corrector considerably simplifies astrophotography, eliminating the need for an external flattener and complex backfocus calculations.
The Askar 91F has been designed to offer a fluid and efficient user experience. Unlike many glasses that require an external corrector, this version directly integrates a correction system optimized for an image circle of 44 mm, perfectly compatible with full-format sensors.
Simply connect your camera via the supplied adapters, focus and start acquiring data without having to deal with complex spacing.
This approach not only reduces hidden costs, but also improves mechanical reliability and setup simplicity.
Askar 91F is based on a four-lens spaced-apart optical formula comprising :
This configuration is highly effective in reducing chromatic aberration, while maintaining excellent sharpness across the entire field.
With its 609 mm focal length, the Askar 91F is particularly suitable for :
One of the great advantages of the Askar 91F is its versatility. This scope can be used for :
For this reason, Askar directly supplies several visual accessories:
The 20 mm eyepiece offers a magnification of approx. 30x, while the 8 mm reaches approx. 76x, enabling observation of landscapes as well as lunar details.
The rectifying prism provides a correctly oriented image, highly appreciated for terrestrial observation.
The Askar 91F boasts a particularly meticulous mechanical construction, high-quality CNC finishing and an elegant blue-and-white design.
The retractable mist shield enhances portability, while the inside of the tube is lined with an absorbent material that effectively limits stray reflections.
The tube also incorporates :
Integrated 1/4” and 3/8” threads allow direct attachment to photo tripods.
The focusing system is based on an imposing eyepiece holder 3-inch Rack & Pinion, designed to support advanced imaging setups without bending.
This focuser includes :
This design ensures precise, stable focusing even with heavy cameras and complex optical trains.
The Askar 91F is supplied with several adapters for easy integration with the majority of equipment on the market.
These include :
This extended compatibility facilitates use with :
| Features | Value |
|---|---|
| Optical type | Quadruplet APO air-spaced with ED glass |
| Opening | 91 mm |
| Focal length | 609 mm |
| Focus report | f/6.7 |
| Image circle | 44 mm Full Frame |
| Field corrector | Integrated |
| Lens holder | 3″ Rack & Pinion double speed |
| Gearbox | 1:10 |
| Rotation | 360° graduated |
| Focuser stroke | 30 mm |
| Minimum length | 513 mm |
| Maximum length | 636 mm |
| Net weight | 3.92 kg |
| Weight with collars and dovetail | 4.52 kg |
| Rear threads | M64, M54, M48 |
| Sensor compatibility | Up to Full Frame |
| Dovetail | Vixen 230 mm |
| Accessories included | 8 mm and 20 mm eyepieces, 45° rectifying prism, photo adapters |
The Askar 91F is a particularly interesting telescope for astronomers looking for an instrument capable of excelling in several fields without major compromise.
Its modern optical formula, integrated corrector, Full Frame compatibility and robust mechanics make it an ideal platform for both advanced astrophotography and visual or terrestrial observation.
Compact, elegant and extremely versatile, Askar 91F is a premium solution for enthusiasts looking for a high-performance, easy-to-use scope.
