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ZWO FF131 APO
ZWO FF131 APO

FF131 APO Flat-Field Apochromatic Refractor

The ZWO FF131 is a large four-element, fully air-spaced apochromatic optical design refractor with a focal length of 983mm and focal ratio of f/7.5. It delivers a flat focal plane over a 44mm image circle, meaning full-frame sensors will not vignette, and will receive sharp star fields from edge to edge.

ZWO FF131 APO

Main features

ZWO FF131 APO

Four-Element Optical Design

The FF131 APO features a four-element, fully air-spaced apochromatic optical design. All four elements work together to deliver a flat imaging field without the need for an additional field flattener.

One ED (extra-low dispersion) glass element is incorporated to effectively reduce chromatic aberration, resulting in improved color correction and image clarity.

44 mm Image Circle — Full-Frame Support

With a 44 mm image circle, the FF131 APO fully supports full-frame sensors and a wide range of imaging setups.

It delivers sharp star fields with excellent edge-to-edge performance, ensuring consistent image quality across the entire frame.

Native Flat-Field Design

The FF131 APO features a native flat-field optical design, eliminating the need for an additional field flattener.

No complex back focus calculations or spacing adjustments are required—simply attach your imaging setup and start capturing once focus is achieved.

Coarse & fine focus adjustment

Equipped with a rigid 3-inch rack-and-pinion focuser, the FF131 APO offers precise control with a 1:10 coarse & fine focus adjustment mechanism.

A built-in 360° rotator at the rear allows for smooth and accurate camera angle adjustments.

Retractable Dew Shield

The FF131 APO features a retractable dew shield, reducing overall length for improved portability.

Precision CNC machining and a high-quality painted finish, combined with an internal anti-reflection coating, help minimize stray light and enhance image contrast.

Quick-Release Mounting Rings

The mounting rings are detachable, allowing for quick and easy setup or teardown of the telescope.

Photography Extension Tube

The FF131 APO is designed for seamless integration with modern imaging systems, and includes a standard four-section photographic extension tube with a 2-inch filter thread. Rear adapters in both M48x0.75 and M54x0.75 formats are also included, making it easy to connect a wide range of cameras, filters, and astrophotography accessories for a clean, flexible setup right out of the box.

Optical layout

 

ZWO FF131 APO

Star field map

 

ZWO FF131 APO

 

 

 

Product Name FF131 APO
Effective Aperture 131mm
Focal Length 983mm
Focal Ratio f/7.5
Objective Type Four-element air-spaced APO(including one ED element)
Image Circle 44mm
Maximum Rear Connection Length (Focuser Retracted)
Imaging Mode 73 mm (measured from the M48×0.75 male thread)
91 mm (measured from the M54×0.75 male thread)
Observation Mode 131 mm (measured from the 1.25″ interface)
142 mm (measured from the 2″ interface)
Minimum Rear Connection Length (Focuser Retracted)
Imaging Mode 42 mm (measured from M48×0.75 male thread)
60 mm (measured from M54×0.75 male thread)
Observation Mode 100 mm (measured from 1.25″ interface)
111 mm (measured from 2″ interface)
Overall Length 878 mm (with 1.25″ interface retracted)
941 mm (with photography extension tube retracted)
963 mm (with 1.25″ interface dew shield extended)
1026 mm (with photography extension tube dew shield extended)
Telescope Body Weight 7.9 kg
Standard Configuration Weight 9.4 kg
(including handle, mounting rings, and dovetail plate)
Rear Interfaces M78 x 1- 55mm Extension Adapter
M78 x 1 – M54 x 0.75
M54 x 0.75 – M54 x 0.75
M54×0.75 – M48×0.75 (built-in M48×0.75 filter thread)

What’s in the Box?

  • ZWO FF131 OTA

  • Photographic extension tube

  • User manual

  • Inspection sheet

  • 1-year Australian warranty

ZWO FF131 APOZWO FF131 APO

Reviews

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ZWO FF131 APO Quadruplet f/7.5

SKU: ZWO-FF131-APO

$3,349.00

Available to order

✅ Fast Shipping & Tracking
✅ Stocked in Melbourne, Australia
✅ Expert Advice
✅ Lifetime Technical Support

    Need Expert Advice?

    Visual Astronomy, Astrophotography, Microscopy and Macro Photography can be a little complicated sometimes as there are a lot of options. If you'd like to check something before you purchase just let us know and we'd be happy to help!

    Enquire now or call us (03) 9042 2293

    ZWO FF131 APO
    ZWO FF131 APO

    ZWO FF131 APO Quadruplet f/7.5

    SKU: ZWO-FF131-APO

    $3,349.00

    Available to order

    FF131 APO Flat-Field Apochromatic Refractor

    The ZWO FF131 is a large four-element, fully air-spaced apochromatic optical design refractor with a focal length of 983mm and focal ratio of f/7.5. It delivers a flat focal plane over a 44mm image circle, meaning full-frame sensors will not vignette, and will receive sharp star fields from edge to edge.

    ZWO FF131 APO

    Main features

    ZWO FF131 APO

    Four-Element Optical Design

    The FF131 APO features a four-element, fully air-spaced apochromatic optical design. All four elements work together to deliver a flat imaging field without the need for an additional field flattener.

    One ED (extra-low dispersion) glass element is incorporated to effectively reduce chromatic aberration, resulting in improved color correction and image clarity.

    44 mm Image Circle — Full-Frame Support

    With a 44 mm image circle, the FF131 APO fully supports full-frame sensors and a wide range of imaging setups.

    It delivers sharp star fields with excellent edge-to-edge performance, ensuring consistent image quality across the entire frame.

    Native Flat-Field Design

    The FF131 APO features a native flat-field optical design, eliminating the need for an additional field flattener.

    No complex back focus calculations or spacing adjustments are required—simply attach your imaging setup and start capturing once focus is achieved.

    Coarse & fine focus adjustment

    Equipped with a rigid 3-inch rack-and-pinion focuser, the FF131 APO offers precise control with a 1:10 coarse & fine focus adjustment mechanism.

    A built-in 360° rotator at the rear allows for smooth and accurate camera angle adjustments.

    Retractable Dew Shield

    The FF131 APO features a retractable dew shield, reducing overall length for improved portability.

    Precision CNC machining and a high-quality painted finish, combined with an internal anti-reflection coating, help minimize stray light and enhance image contrast.

    Quick-Release Mounting Rings

    The mounting rings are detachable, allowing for quick and easy setup or teardown of the telescope.

    Photography Extension Tube

    The FF131 APO is designed for seamless integration with modern imaging systems, and includes a standard four-section photographic extension tube with a 2-inch filter thread. Rear adapters in both M48x0.75 and M54x0.75 formats are also included, making it easy to connect a wide range of cameras, filters, and astrophotography accessories for a clean, flexible setup right out of the box.

    Optical layout

     

    ZWO FF131 APO

    Star field map

     

    ZWO FF131 APO

     

     

     

    Product Name FF131 APO
    Effective Aperture 131mm
    Focal Length 983mm
    Focal Ratio f/7.5
    Objective Type Four-element air-spaced APO(including one ED element)
    Image Circle 44mm
    Maximum Rear Connection Length (Focuser Retracted)
    Imaging Mode 73 mm (measured from the M48×0.75 male thread)
    91 mm (measured from the M54×0.75 male thread)
    Observation Mode 131 mm (measured from the 1.25″ interface)
    142 mm (measured from the 2″ interface)
    Minimum Rear Connection Length (Focuser Retracted)
    Imaging Mode 42 mm (measured from M48×0.75 male thread)
    60 mm (measured from M54×0.75 male thread)
    Observation Mode 100 mm (measured from 1.25″ interface)
    111 mm (measured from 2″ interface)
    Overall Length 878 mm (with 1.25″ interface retracted)
    941 mm (with photography extension tube retracted)
    963 mm (with 1.25″ interface dew shield extended)
    1026 mm (with photography extension tube dew shield extended)
    Telescope Body Weight 7.9 kg
    Standard Configuration Weight 9.4 kg
    (including handle, mounting rings, and dovetail plate)
    Rear Interfaces M78 x 1- 55mm Extension Adapter
    M78 x 1 – M54 x 0.75
    M54 x 0.75 – M54 x 0.75
    M54×0.75 – M48×0.75 (built-in M48×0.75 filter thread)

    What’s in the Box?

    • ZWO FF131 OTA

    • Photographic extension tube

    • User manual

    • Inspection sheet

    • 1-year Australian warranty

    ZWO FF131 APOZWO FF131 APO

    Reviews

    There are no reviews yet.

    Be the first to review “ZWO FF131 APO Quadruplet f/7.5”

    Your email address will not be published. Required fields are marked *

      Need Expert Advice?

      Visual Astronomy, Astrophotography, Microscopy and Macro Photography can be a little complicated sometimes as there are a lot of options. If you'd like to check something before you purchase just let us know and we'd be happy to help!

      Enquire now or call us (03) 9042 2293