Askar Launches 4-Element ED Apochromatic Telescopes "111F" and "131F" with Built-in Flatteners (111mm/131mm Aperture) and Dedicated 0.74x Reducers

SITRON JAPAN Co., Ltd. (Head Office: Shinjuku-ku, Tokyo, Representative Director: Akira Watanabe) will launch the "111F" and "131F" 4-element apochromatic telescopes with built-in flatteners, and their dedicated corrector lenses "111F 0.74x Reducer" and "131F 0.74x Reducer" from Jiaxing Ruixing Optical Instrument's brand "Askar" for astrophotography, around late July 2026. Pre-orders will begin on July 3, 2026.

The "111F" and "131F" feature a 4-element optical system (3 elements in the front group + 1 element in the rear group) including one ED glass element, which corrects chromatic aberration and field curvature, enabling astrophotography with full-frame sensors without the need for additional corrector lenses. Furthermore, they are compatible with visual observation using the included eyepiece adapter, making them versatile models capable of both observation and serious photography with a single unit.

Product Features

Flat-field optical system with ED lens and built-in flattener, 4-element construction (common to 111F & 131F)

The optical system employs an apochromatic design with 4 elements in 4 groups, with 3 elements placed at the objective end and 1 element at the rear. Using one ED glass element effectively suppresses chromatic aberration, producing sharp star images with high contrast.

The design corrects for field curvature and various aberrations, maintaining excellent star images across the entire 44mm diameter image circle. This supports serious astrophotography using full-frame sensors.

Spot diagrams for 111F and 131F are available.

Eyepiece section compatible with both photography and visual observation (common to 111F & 131F)

A standard accessory is a 4-section extension tube for photography with a built-in M48 filter thread. Various cameras can be attached using the included M54/M48 adapter.

The back focus for photography supports 43-73mm from the M48x0.75 threaded base. The design facilitates the construction of imaging systems incorporating off-axis guiders and filter drawers.

50.8mm and 31.7mm adapters are included. Visual observation can be enjoyed by attaching optional diagonal mirrors and eyepieces.

Tube mechanism that is easy to handle in the field (common to 111F & 131F)

The lens hood adopts a retractable design. When stored, it can be retracted to shorten the overall length, making it convenient for carrying and storage. Baffles are incorporated inside the tube to effectively suppress stray light.

The handle bar is equipped with a slot for a finder mount. Two finder bases are also provided on both sides of the focuser, allowing for changes in finder mounting position or simultaneous attachment of accessories like guide scopes without disassembly.

The tube rings are openable and detachable without tools.

A large rack and pinion focuser is installed. Precise focusing is possible with the micro-focus knob with a reduction mechanism. The focus stroke is 31mm.

The focuser is equipped with a 360° rotation mechanism. Accurate framing adjustments can be made while checking the angle scale on the inner tube.

Compatible with various electric focusers, including ZWO's EAF.

Easy-to-handle 111mm aperture, F6.9 (111F)

This model uses an optical system with a 111mm aperture, 766mm focal length, and F6.9. It is suitable for a wide range of targets, from faint galaxies, nebulae, and star clusters to the Moon.

The mass is 5.74kg for the tube only, and 6.76kg including the tube rings and dovetail bar. It is a class that can be easily taken out for field photography.

A 300mm long, narrow dovetail bar with 1/4-inch and 3/8-inch screw holes is included, allowing for direct mounting on a tripod.

When the optional "111F 0.74x Reducer" is attached, it can be used as a bright optical system with a focal length of 566mm and F5.1.

Large light-gathering power with 131mm aperture, F7.5 (131F)

This model uses an optical system with a 131mm aperture, 983mm focal length, and F7.5. With greater light-gathering power and focal length than the 111F, it is suitable for higher resolution deep-sky photography.

The mass is 7.9kg for the tube only, and 9.4kg including the tube rings and dovetail bar.

A 300mm long, wide dovetail bar is included, allowing for stable mounting on medium-sized equatorial mounts.

When the optional "131F 0.74x Reducer" is attached, it can be used as a bright optical system with a focal length of 733.6mm and F5.6.

Dedicated reducer (sold separately) that shortens focal length by 0.74x

Shortening the focal length expands the field of view and reduces exposure time. This allows for lighter shooting of faint, extended nebulae and star clusters.

The 3-element optical design corrects field curvature and supports a 44mm diameter full-frame image circle.

The back focus is 55mm from the M48x0.75 threaded base. The adapter section has a built-in M48 filter thread, allowing filters to be attached without additional adapters.

The mass is 0.5kg for the 111F version and 0.56kg for the 131F version. Metal front and rear screw-on caps are included to protect the lens during storage and transport.

Spot diagrams for the 111F 0.74x Reducer and 131F 0.74x Reducer are available.

Reliable domestic inspection (common to 111F & 131F)

SITRON JAPAN has established strict domestic quality standards to ensure customers can purchase Askar/SHARPSTAR products with confidence. At our Niigata Tainai factory and Tokyo head office, we conduct visual and optical axis inspections using dedicated equipment for incoming products, and only ship and sell products that meet these standards.

Sample photos:

©Daidaiko, IC443 / Askar 111F Flat-Field + Touptek ATR2600M

©Nazmus Nasir, M27 / Askar 131F Flat-Field

Main Specifications

Product Name

Askar 111F

Aperture

111mm

Focal Length

766mm

F-ratio

F6.9

Optical System

4-element air-spaced apochromat

(3 elements in front group + 1 element in rear group, 1 ED glass element, built-in flattener)

Image Circle

φ44mm (Full-frame compatible)

Overall Length

(Including 31.7mm adapter)

664mm (Hood retracted)

751mm (Hood extended)

Mass

5.74kg (tube only) / 6.76kg (including tube rings and dovetail bar)

Camera Mount Adapter

M48 (M48x0.75 filter attachable) / M54

Back Focus

42-73mm (from M48x0.75 threaded base)

Focuser

Rack & pinion type, 31mm stroke, reduction gear

Eyepiece Adapter

50.8mm / 31.7mm

Field Rotator

360° rotation mechanism (with angle scale)

Dovetail Bar

Narrow type, 300mm length (with 1/4-inch and 3/8-inch screw holes)

Accessories

Tube (including tube rings, handle bar, dovetail bar), 4-section extension tube for photography, 50.8mm adapter, 31.7mm adapter, Instruction Manual, Warranty Card

Product Name

Askar 131F

Aperture

131mm

Focal Length

983mm

F-ratio

F7.5

Optical System

4-element air-spaced apochromat

(3 elements in front group + 1 element in rear group, 1 ED glass element, built-in flattener)

Image Circle

φ44mm (Full-frame compatible)

Overall Length

(Including 31.7mm adapter)

878mm (Hood retracted)

963mm (Hood extended)

Mass

7.9kg (tube only) / 9.4kg (including tube rings and dovetail bar)

Camera Mount Adapter

M48 (M48x0.75 filter attachable) / M54

Back Focus

42-73mm (from M48x0.75 threaded base)

Focuser

Rack & pinion type, 31mm stroke, reduction gear

Eyepiece Adapter

50.8mm / 31.7mm

Field Rotator

360° rotation mechanism (with angle scale)

Dovetail Bar

Wide type, 300mm length

Accessories

Tube (including tube rings, handle bar, dovetail bar), 4-section extension tube for photography, 50.8mm adapter, 31.7mm adapter, Instruction Manual, Warranty Card

Product Name

Askar 111F 0.74x Reducer

Magnification

0.74x

Focal Length when attached

566mm

F-ratio when attached

F5.1

Optical System

3-element construction

Image Circle

φ44mm (Full-frame compatible)

Back Focus

55mm (from M48x0.75 threaded base)

Filter

Built-in M48x0.75 filter attachment thread

Mass

0.5kg

Accessories

Metal front and rear screw-on caps

Product Name

Askar 131F 0.74x Reducer

Magnification

0.74x

Focal Length when attached

733.6mm

F-ratio when attached

F5.6

Optical System

3-element construction

Image Circle

φ44mm (Full-frame compatible)

Back Focus

55mm (from M48x0.75 threaded base)

Filter

Built-in M48x0.75 filter attachment thread

Mass

0.56kg

Accessories

Metal front and rear screw-on caps

Launch Outline

Brand

Askar

Product Names

111F

131F

111F 0.74x Reducer

131F 0.74x Reducer

Suggested Retail Price

Open Price

Estimated Market Price

*All prices include tax

111F: Around ¥230,000

131F: Around ¥300,000

111F 0.74x Reducer: Around ¥45,000

131F 0.74x Reducer: Around ¥45,000

Pre-order Start Date

July 3, 2026 (Fri)

Release Date

Scheduled for late July 2026

*The estimated market price is solely our company's prediction and may differ from the actual selling price.

*This press release is created based on manufacturer information and provided images. Appearance, specifications, and accessories are subject to change without notice.

*Company names and product names mentioned are trademarks or registered trademarks of their respective companies.

*This product will be handled exclusively by specialized telescope stores and our directly managed stores.

[Contact Information Regarding This Product]

SITRON JAPAN Co., Ltd.

Customer Service Center TEL: 03-6908-3116

SITRON JAPAN Co., Ltd.

Founded in 1961 as a specialized trading company dealing in optical products such as binoculars. Currently, in addition to manufacturing and selling optical equipment such as binoculars, telescopes, and filters, we also handle the Japanese distribution of overseas interchangeable lens brands and world-class telescope manufacturers. We also cooperate with stargazing events and events organized by companies and local governments.

https://www.sightron.co.jp