ZWO FF90 90/609 APO Refractor OTA | PixelSkiesAstro
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  • ZWO FF90 90/609 APO Refractor OTA | PixelSkiesAstro
  • ZWO FF90 90/609 APO Refractor OTA | PixelSkiesAstro
  • ZWO FF90 90/609 APO Refractor OTA | PixelSkiesAstro
  • ZWO FF90 90/609 APO Refractor OTA | PixelSkiesAstro
  • ZWO FF90 90/609 APO Refractor OTA | PixelSkiesAstro
  • ZWO FF90 90/609 APO Refractor OTA | PixelSkiesAstro
  • ZWO FF90 90/609 APO Refractor OTA | PixelSkiesAstro
  • ZWO FF90 90/609 APO Refractor OTA | PixelSkiesAstro
  • ZWO FF90 90/609 APO Refractor OTA | PixelSkiesAstro
  • ZWO FF90 90/609 APO Refractor OTA | PixelSkiesAstro

ZWO FF90 90/609 APO Refractor OTA

€1,390.00
Tax included

ZWO FF90 APO — 90 mm flat-field refractor A 609 mm, f/6.8 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 FF90 90/609 APO Refractor OTA · Specifications checked against manufacturer data on 2026-11-03

ZWO FF90 APO — 90 mm flat-field refractor

A 609 mm, f/6.8 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 45–75 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 3.92 kg; the standard configuration with handle, rings and dovetail weighs 4.52 kg.

ZWO FF90 manufacturer specifications

Compatibility notes

Native flat field design does not require an added flattener; the imaging train must still fit the available focus travel and interface.

Additional specifications

Focuser size inches3
Camera rotator degrees360
Mounting ringsDetachable
Length visual retracted (mm)513
Length imaging retracted (mm)550
Length visual extended (mm)599
Length imaging extended (mm)636
93003

Data sheet

Aperture (mm)
90
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)
609
Focal ratio
6.8
Focuser type
Rack and pinion, dual speed
Image circle (mm)
44
Imaging focus range
45–75 mm from M54–M48 shoulder
Maximum optical path m48 (mm)
75
Maximum optical path m54 (mm)
93
Maximum visual path 1 25 inch (mm)
112
Maximum visual path 2 inch (mm)
122
Optical design
Four-element air-spaced apochromat; one ED element
Rear adapter threads
M64 × 1 → M54 × 0.75; M54 × 0.75 → M54 × 0.75; M54 × 0.75 → M48 × 0.75
Standard weight (kg)
4.52
Standard weight includes
Handle, mounting rings and dovetail plate
Telescope body weight (kg)
3.92
Telescope model
FF90 APO
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