$ZWO FF131 131/983 APO Refractor OTA | PixelSkiesAstro$
$ZWO FF131 131/983 APO Refractor OTA | PixelSkiesAstro$
$ZWO FF131 131/983 APO Refractor OTA | PixelSkiesAstro$
$ZWO FF131 131/983 APO Refractor OTA | PixelSkiesAstro$
$ZWO FF131 131/983 APO Refractor OTA | PixelSkiesAstro$
$ZWO FF131 131/983 APO Refractor OTA | PixelSkiesAstro$
$ZWO FF131 131/983 APO Refractor OTA | PixelSkiesAstro$
$ZWO FF131 131/983 APO Refractor OTA | PixelSkiesAstro$
$ZWO FF131 131/983 APO Refractor OTA | PixelSkiesAstro$
$ZWO FF131 131/983 APO Refractor OTA | PixelSkiesAstro$

ZWO FF131 131/983 APO Refractor OTA

ZWO FF131 APO — 131 mm flat-field refractor A 983 mm, f/7.5 optical tube for astrophotography and visual observing. Its four air-spaced elements include ED glass for colour correction. The native flat field covers a 44 mm image circle without a separate flattener.

Manufacturer model: ZWO FF131 131/983 APO Refractor OTA · Specifications checked against manufacturer data on 2026-11-03

Description
Product Details

ZWO FF131 APO — 131 mm flat-field refractor

A 983 mm, f/7.5 optical tube for astrophotography and visual observing. Its four air-spaced elements include ED glass for colour correction. The native flat field covers a 44 mm image circle without a separate flattener.

Focus and framing

The 3-inch rack-and-pinion focuser has 1:10 fine adjustment. A 360° rear rotator sets camera orientation. ZWO specifies an imaging focus range of 42–73 mm from M54–M48 shoulder; this is a usable focusing range, rather than a fixed reducer-spacing requirement.

Camera connections

M48 × 0.75 and M54 × 0.75 interfaces accommodate imaging trains. The photographic extension accepts a 2-inch threaded filter. Eyepiece interfaces support visual use.

Handling and installation

A retractable dew shield shortens the tube for transport. Detachable rings support mounting. Body weight is 7.9 kg; the standard configuration with handle, rings and dovetail weighs 9.4 kg.

ZWO FF131 manufacturer specifications

Compatibility notes

These specifications describe the telescope component only. Native flat field design does not require an added flattener; the imaging train must still fit the available focus travel and interface. Package mount/tripod specifications are not inferred from telescope data.

Additional specifications

Focuser size inches	3
Camera rotator degrees	360
Mounting rings	Detachable
Length visual retracted (mm)	878
Length imaging retracted (mm)	941
Length visual extended (mm)	963
Length imaging extended (mm)	1026

Reference 93005

Data sheet

Aperture (mm): 131
Applications: Astrophotography and visual observing
Dew shield: Retractable
External field flattener required: No
Filter thread: M48 × 0.75 (2-inch)
Fine focus ratio: 1:10
Focal length (mm): 983
Focal ratio: 7.5
Focuser type: Rack and pinion, dual speed
Image circle (mm): 44
Imaging focus range: 42–73 mm from M54–M48 shoulder
Maximum optical path m48 (mm): 73
Maximum optical path m54 (mm): 91
Maximum visual path 1 25 inch (mm): 131
Maximum visual path 2 inch (mm): 142
Optical design: Four-element air-spaced apochromat; one ED element
Rear adapter threads: M78 × 1 with 55 mm extension; M78 × 1 → M54 × 0.75; M54 × 0.75 → M54 × 0.75; M54 × 0.75 → M48 × 0.75
Standard weight (kg): 9.4
Standard weight includes: Handle, mounting rings and dovetail plate
Telescope body weight (kg): 7.9
Telescope model: FF131 APO

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