- Commodity name: 131F Flat-Field
- Commodity ID: 131F Flat-Field
Self-flattened quadruplet Astrograph which can be used for visual observing and astrophotography.
口径131mm
131mm Aperture
焦距983mm
983mm Focal Length
4片式APO设计
Quadruplet Air-Spaced APO
ED玻璃
ED Glass
全画幅对应
Supporting Full Frame
无需平场镜
No Need for Flattener
无需计算后截距
拍摄即接即用
No Need to Calculate the Backfocus
可伸缩遮光罩
Retractable Lens Hood
360度旋转器
Rotator
2个寻星镜基座
2 Finder Bases
1:10微调精密
1:10 Fine Adjustment
3英寸有齿
（R&P）调焦器
3" Large Rack- Pinion Focuser
1.25英寸/2英寸目镜接口
1.25"/2" Visual Adapter
300mm宽型鸠尾板
300mm Losmandy Dovetail plate
摄影延长管
4-piece Photographic Adapters

The Askar 131F is a large-aperture telescope designed for astronomy enthusiasts, featuring a 131mm aperture, 983mm focal length, and a native F7.5 focal ratio.

It employs a quadruplet optical lens design with three elements in the front and one in the rear, including one piece of ED glass to effectively suppress chromatic aberration.
The lens tube incorporates an internal baffle to block stray light, further enhancing image quality. The Askar 131F supports full-frame imaging and delivers excellent star performance across the frame.
Continuing the F series' self-flattening design, users can achieve optimal imaging without purchasing an additional flattener or calculating back focus. Simply connect the imaging accessory, achieve focus, and you're ready to shoot—streamlining the process and lowering the barrier to use.

The telescope comes standard with a photographic extension tube featuring a built-in 2-inch filter thread and offers M48×0.75 and M54×0.75 adapters for broad compatibility with DSLR cameras and dedicated astronomy cameras, meeting diverse imaging needs.
Staying true to the brand philosophy, the Askar 131F balances optical performance with user experience. The lens tube is crafted with high-quality CNC machining and painted finish, continuing the F series' iconic blue-and-white color scheme for strong visual identity.
Whether for deep-sky imaging or visual observation, the Askar 131F is an ideal choice for advancing your astrophotography journey.

Parameters
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

Product Size Diagram

Connection Diagram

The Locking Screw Position Diagram

Electronic Focuser Assembly Diagram

Optical Path Diagram

Spot Diagram

NGC281 | 张宇航 | Askar 91F Flat-Field + ZWO ASI2600MC
NGC7293 | 张宇航 | Askar 91F Flat-Field + ZWO ASI2600MC
Gyulbudaghian's Nebula | Nico Carver | Askar 91F + ZWO ASI2600MC Air

Product introduction

口径131mm

131mm Aperture

焦距983mm

983mm Focal Length

4片式APO设计
Quadruplet Air-Spaced APO

ED玻璃
ED Glass

全画幅对应
Supporting Full Frame

无需平场镜
No Need for Flattener

无需计算后截距
拍摄即接即用
No Need to Calculate the Backfocus

可伸缩遮光罩
Retractable Lens Hood

360度旋转器
Rotator

2个寻星镜基座
2 Finder Bases

1:10微调精密
1:10 Fine Adjustment

3英寸有齿
（R&P）调焦器
3" Large Rack- Pinion Focuser

1.25英寸/2英寸目镜接口
1.25"/2" Visual Adapter

300mm宽型鸠尾板
300mm Losmandy Dovetail plate

摄影延长管
4-piece Photographic Adapters

The Askar 131F is a large-aperture telescope designed for astronomy enthusiasts, featuring a 131mm aperture, 983mm focal length, and a native F7.5 focal ratio.

It employs a quadruplet optical lens design with three elements in the front and one in the rear, including one piece of ED glass to effectively suppress chromatic aberration.

The lens tube incorporates an internal baffle to block stray light, further enhancing image quality. The Askar 131F supports full-frame imaging and delivers excellent star performance across the frame.

Continuing the F series' self-flattening design, users can achieve optimal imaging without purchasing an additional flattener or calculating back focus. Simply connect the imaging accessory, achieve focus, and you're ready to shoot—streamlining the process and lowering the barrier to use.

The telescope comes standard with a photographic extension tube featuring a built-in 2-inch filter thread and offers M48×0.75 and M54×0.75 adapters for broad compatibility with DSLR cameras and dedicated astronomy cameras, meeting diverse imaging needs.

Staying true to the brand philosophy, the Askar 131F balances optical performance with user experience. The lens tube is crafted with high-quality CNC machining and painted finish, continuing the F series' iconic blue-and-white color scheme for strong visual identity.

Whether for deep-sky imaging or visual observation, the Askar 131F is an ideal choice for advancing your astrophotography journey.

Specifications

Parameters
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