Askar 131F - 131 mm f/7.5 Quadruplet Flat-Field APO Refractor - 131F
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Askar 131 mm Quad ED APO Flat-Field Refractor
Askar 131F Flat Field Quad Refractor Highlights
The Askar 131F is a telescope OTA with an aperture of 131mm, a focal length of 983mm, and a native focal ratio of F/7.5. It is designed for both visual observation and astrophotography.
The quadruplet lens system—comprising three front elements and one rear element, including one piece of ED glass—effectively minimizes chromatic aberration and supports 44mm full-frame imaging.
This 131 mm Quadruplet Refractor has a self-flattened design that allows users to avoid calculating the back focus and buying an additional flattener. After attaching the imaging accessories, users can use it for photography after the OTA is in focus. This further reduces the cost and improves the pleasure imaging through your 131F.
Adhering to Askar's consistent design philosophy, the Askar 131F emphasizes detail and user experience, striving to reduce the cost of use. The lens hood is retractable, further shortening the overall length and enhancing portability. The lens tube utilizes high-quality CNC machining and painting processes. Its appearance continues the F-series' classic blue and white color scheme, presenting a simple and elegant aesthetic.
The Askar 131F comes standard with a photographic extension tube, which is designed with a 2-inch filter thread. It includes adapters with M48*0.75 and M54*0.75 specifications, ensuring compatibility with DSLR cameras or astronomy cameras to meet diverse needs.
The Askar 111F is equipped with a 3-inch rack-and-pinion dual-speed focuser supporting 1:10 fine adjustment. The fine adjustment knob includes a protective cap to prevent damage. The rear of the focuser connects to a 360° graduated rotator, allowing for precise angle adjustments.
The handle of the Askar 131F is equipped with a finder base slot. Additionally, both sides of the focuser feature finder bases. This not only allows for changing the finder scope position without disassembly but also provides more locations for installing other astronomical accessories.
The 300 mm Losmandy dovetail plate of the Askar 131F is compatible with most equatorial mounts and bases on the market. The dovetail plate is designed with multiple holes, which makes it easy to adjust the position. The entire plate is manufactured using high-quality CNC machining.
The optional 0.74x reducer, shown above, brings the Askar 131F's focal ratio down to F/5.6. This reducer features a triplet optical design and supports a 44mm full-frame image circle.
Specifications
| Aperture size | 131mm | |
| Focal length | 983mm | |
| Focal ratio | f/7.5 | |
| Objective lens | Quadruplet air-spaced APO(including one ED glass) | |
| Image circle | 44mm | |
| Maximum accessory connection (with the focuser fully retreated) |
Imaging mode: 73mm (from the base of M48×0.75 male thread） 91mm（from the base of M54×0.75 male thread) |
Observing mode: 131mm（from the end of 1.25" eyepiece holder） 141mm（from the end of 2" eyepiece holder） |
| Minimum accessory connection (with the focuser fully extended) |
Imaging mode: 43mm (from the base of M48×0.75 male thread） 61mm（from the base of M54×0.75 male thread) |
Observing mode: 101mm（from the end of 1.25" eyepiece holder） 111mm（from the end of 2" eyepiece holder） |
| Total length |
878mm(including 1.25" adapter as dew shield contracted） 963mm(including 1.25" adapter as dew shield fully stretched） 941mm(including the photographic adapter as dew shield contracted） 1026mm(including the photographic adapter as dew shield fully stretched） |
|
| Focuser travel length | 30mm | |
| Net weight | 7.9kg | |
| Gross weight (Including tube ring&dovetail plate) | 9.4kg | |
| Rear-end thread type |
M78×1-M54×0.75 M54×0.75-M54×0.75 M54×0.75-M48×0.75 (with M48×0.75 filter thread) |
|
| Standard package items | A 131F OTA, a pair of tube rings, a handle, a 300mm Losmandy dovetail plate, a set of photographic adapters | |