ZWO FF90 APO Refractor Telescope

BH #ZWFF90APO • MFR #ZWO FF90-APO
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ZWO FF90 APO Refractor Telescope
Key Features
  • 90mm Apochromatic OTA
  • 609mm Focal Length, f/6.8 Focal Ratio
  • Air-Spaced Quad APO with 1 ED Element
  • Eliminates Need for Field Flattener
Equally suited to observation and astrophotography, the FF90 APO Refractor Telescope from ZWO features a quadruplet air-spaced apochromatic lens system that eliminates the need for a separate field flattener. The quad APO includes one extra-low dispersion element and dramatically reduces chromatic aberration. It also eliminates the need to calculate back focus distance—just attach your camera with one of the four included adapters and you're ready for imaging. The f/6.8 focal ratio and 609mm focal length collect the light needed for long-exposure, deep-sky photography, but add a diagonal with a high-magnification eyepiece and the scope is ideal for planetary observation.
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ZWO FF-90 Overview

Equally suited to observation and astrophotography, the FF90 APO Refractor Telescope from ZWO features a quadruplet air-spaced apochromatic lens system that eliminates the need for a separate field flattener. The quad APO includes one extra-low dispersion element and dramatically reduces chromatic aberration. It also eliminates the need to calculate back focus distance—just attach your camera with one of the four included adapters and you're ready for imaging. The f/6.8 focal ratio and 609mm focal length collect the light needed for long-exposure, deep-sky photography, but add a diagonal with a high-magnification eyepiece and the scope is ideal for planetary observation.

Optical Tube Assembly
  • f/6.8 focal ratio and 609mm focal length allow for both deep-sky and planetary imaging
  • Quadruplet air-spaced apochromatic refractor design with one ED element produces rich views with minimal chromatic aberration
  • APO is self-flattening, eliminating the need for a separate field flattener
  • Supports 44mm image circle for full-frame cameras
Focuser
  • Sturdy 3" rack-and-pinion focuser easily carries large and heavy eyepieces, accessories like Barlows and focal reducers, and imaging systems
  • 2" and 1.25" adapters
  • 360° rotator with scales and finder base
  • 10:1 fine adjustment ratio
Use and Handling
  • Anodized red handle and tube ring assembly can be detached and reinstalled in seconds
  • Photography extension tube with M54 and M48 adapters
  • Retractable dew shield's interior is matte painted to reduce reflections
  • CNC-machined aluminum optical tube
  • Finderscope bases on both sides of focuser and base slot on handle
  • 230mm Vixen-style dovetail plate
EAN: 6977641322393

ZWO FF-90 Specs

Key Specs
Aperture
4" / 90 mm
Focal Length
609 mm
Focal Ratio
f/6.8
Eyepiece
Sold Separately
Optical Design
Apochromatic Refractor
Aperture
4" / 90 mm
Focal Length
609 mm
Focal Ratio
f/6.8
Focuser
Dual-Speed Rack-and-Pinion
Eyepiece
Sold Separately
Finderscope
No
Mounting
Vixen Style
Optical Tube Dimensions
20.9" / 531 mm (Retracted)
23.6" / 599 mm (Extended)
General
Weight
9.9 lb / 4.5 kg
Packaging Info
Package Weight
13.915 lb
Box Dimensions (LxWxH)
23.1 x 10.9 x 9.7"

ZWO FF-90 Reviews

An excellent choice

By James
Rated 5 out of 5
Date: 2026-07-21

There is so much to like about this telescope. The quad APO optics are excellent. No field flattener needed. I had an 80 mm refractor, but wanted to step up a little in focal length and light gathering without getting too large for my mount. My scope, ASIAIR and guide scope combination is only 12 pounds. The focusing is very easy, although I did have to go to 70 mm extensions (not the usual 55) to reach focus. The tube ring assembly has base mounts for both the finder scope and the ASIAIR. The whole system works so well together it is a pleasure to set it up, find a target and let it go to work. I am very pleased.

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