Askar 91F f/6.7 Quadruplet Flat-Field Astrograph
| Article number: | ASKAR-91F |
| Availability: | More on the Way to us |
| Delivery time: | More on the Way to Us |
The Askar 91F is a versatile 91mm quadruplet astrograph designed for both astrophotography and visual observation. Its 609mm focal length and f/6.7 focal ratio provide a useful combination of light-gathering power and field of view, while the four-element air-spaced APO design incorporates one ED element for improved chromatic aberration correction.
The 91F uses a self-flattened optical design with a 44mm image circle, allowing full-frame cameras to be used without requiring a separate field flattener or complicated backfocus calculations. Simply attach the appropriate imaging accessories, achieve focus, and the telescope is ready for imaging.
Key Specifications:
- 91mm aperture
- 609mm focal length
- f/6.7 focal ratio
- Quadruplet air-spaced APO optical design
- One ED glass element
- 44mm image circle
- Full-frame compatible
- Integrated self-flattening optical design
- 3" dual-speed rack-and-pinion focuser
- 30mm focuser travel
- 1:10 fine adjustment
- 360° rotator with graduated scale
- Retractable dew shield
- Two finder bases
- 130mm multifunction handle with finder base slot
- 1.25" and 2" visual adapters
- Photographic extension tube with built-in 2" filter thread
- M48 and M54 photographic adapters
- 230mm Vixen-style dovetail plate
Use Cases:
- Full-frame deep-sky astrophotography
- Nebula and galaxy imaging
- DSLR and mirrorless camera astrophotography
- Dedicated astronomy camera imaging
- Lunar and planetary observation
- Visual deep-sky observing
- Portable astronomy and travel