ZWO FF90 APO Refractor with AM3N Bundle
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FF90 APO Refractor
The ZWO FF90 APO Refractor is a lightweight, compact refractor telescope designed for visual observation and astrophotography.
*Focus is achieved within a 45–75 mm back focus range, measured from the M54–M48 interface shoulder.
Main Features
Flexible Connectivity for Multiple Configurations
Powerful Uniqueness
1. Lightweight & Compact
This unit features a 90 mm aperture and 609 mm focal length (f/6.8) for portability and performance.
The optical tube weighs 3.92 kg. Total system weight is 4.52 kg including the mounting rings and dovetail plate.
2. Four-Element Optical Design
The optics use a four-element, air-spaced apochromatic design. All elements work together to deliver a flat imaging field.
One ED glass element effectively reduces chromatic aberration. This results in superior color correction and image clarity.
3. 44 mm Image Circle — Full-Frame Support
With a 44 mm image circle, the unit supports full-frame sensors. It is ideal for use with an asiair pro for smart control.
It delivers sharp star fields with excellent edge-to-edge performance. This ensures consistent quality across the frame.
4. Native Flat-Field Design
The optical system features a native flat-field design. This eliminates the need for an additional field flattener.
Complex back focus calculations are not required. Simply attach your imaging setup and start capturing once focused.
Convenient Mechanical Design
5. Coarse & Fine Focus Adjustment
Equipped with a rigid 3-inch rack-and-pinion focuser, it offers precise 1:10 dual-speed coarse and fine adjustments.
A built-in 360° rotator at the rear allows for smooth, accurate camera angle adjustments during your session.
6. Retractable Dew Shield
This model features a retractable dew shield for portability. This helps protect your optical tube in the field.
Precision CNC machining and internal anti-reflection coatings help minimize stray light to enhance image contrast.
7. Quick-Release Mounting Rings
The mounting rings are detachable. This allows for quick and easy setup or teardown at any dark site.
8. Photography Extension Tube
The package includes a photography extension tube with a 2-inch filter thread and M48 and M54 adapters.
These components allow for easy integration with a wide range of modern imaging accessories and cameras.
Performance Charts
Optical Layout
Star Field Map
AM3N Mount
Please Note : Power cable not included: ZWO-DC12V5A-US
Why AM3N ?
AM3N vs AM3
Engineered for simplicity: two cables deliver a clean, efficient setup that gets you imaging faster than ever.
Strain Wave Gears for Precision Control
Astrophotography demands both stability and accuracy, and the adoption of a custom-engineered strain wave gear system addresses these needs directly. The gear train is designed to minimize periodic error, provide exceptionally smooth motion, and deliver high torque capacity—factors critical for long-exposure imaging.
Within the mount, a strain wave gear reducer works in concert with a synchronous belt drive, yielding precise control and a notable 300:1 reduction ratio. Each unit undergoes individual testing, and a periodic error (PE) curve report is supplied with every mount, offering users verified performance data for confidence in the field.
ZWO Quality Control
ZWO measures each mount and equips it with an exclusive PE curve before it leaves our factory.
The X-axis represents the drive angle, and the Y-axis shows the periodic error, which is consistently maintained within ±15 arcseconds.
Integrated Type-C and DC Power Ports
The upgraded AM3N weighs just 4.1 kg (9.04 lbs), with a newly optimized design for improved portability and cable management. The dovetail saddle now integrates Type-C and 12V DC ports to minimize clutter, while a magnetic hex key attaches directly to the mount for convenient storage.
Powerful Payload Capacity: 8 –13 kg
The mount supports up to 8 kg (17.6 lbs) without counterweights—double its own weight—and up to 13 kg (28.7 lbs) with counterweights, more than triple its weight.
This payload capacity easily accommodates a wide range of telescopes, providing a stable and reliable foundation for your viewing and imaging needs.
It is recommended to use a counterweight of ≤5 kg. When using a 5 kg counterweight, the lever arm should be installed within the range of 20 cm to 30 cm.
For counterweights of other masses, the installation position can be calculated as follows:
Assume the counterweight mass is m kg. The allowable lever arm length L is defined by:
10 N·m ≤ m × g × L ≤ 15 N·m
where g = 9.8 m/s², which can be approximated as 10 m/s².
For example, if a 2 kg counterweight is used, the allowable range of L is from
10 N·m / (2 × 10 m/s²) = 0.5 m to
15 N·m / (2 × 10 m/s²) = 0.75 m.
Equatorial Mode / Alt-azimuth Mode
Can be switched via SkyAtlas App or Hand Controller.
Status Light Indicator
All-round 0°-90° Altitude Scale
The AM3N features a versatile altitude adjustment design ranging from 0° to 90°, allowing for unrestricted use across both low-and high-latitude regions.
Gear 1: Rotate the altitude tension knob for adjustment between 0 and 60.
Gear 2: Loosen the M6 hex screw, and allows adjustment from 30 and 90.
Evolved Portable Control Wi-Fi & Bluetooth Connectivity
The AM3N supports Bluetooth control, enabling direct smartphone control — no Hand Controller required. Wi-Fi functionality is available through the hand controller, which contains the WiFi transmitter. Ideal for travel and field use, just bring your phone and you're ready to observe or image.
Wireless Control via Mobile Apps
Operate the mount directly from your phone with an intuitive app featuring an on-screen joystick, Tonight’s Target, GOTO, Live Preview, and more.
The mount is compatible with ASCOM, INDI, ASIAIR, and other platforms.
Seamless ASIAIR Integration
Experience astrophotography at its best with the ZWO Ecosystem—where every component works together in perfect harmony.
Technical Specifications
FF90 APO Refractor
AM3N Mount
| Item |
Specification |
| Mount Type |
Harmonic Drive Mount |
| Mount Mode |
Equatorial / Altazimuth |
| Drive |
Strain Wave Gear + Synchronous Belt (300:1 reduction ratio) |
| Periodic Error |
≤ ±15″ |
| PE Duration |
288 s |
| Payload Capacity |
8 kg (17.64 lbs) without counterweight13 kg (28.66 lbs) with counterweight |
| Mount Weight |
4.1 kg (9.04 lbs) |
| Altitude Adjustment Range |
0°–90° |
| Azimuth Adjustment Range |
±6° |
| Dovetail Saddle |
Losmandy & Vixen |
In the Box
Refractor
- FF90 APO Telescope
- Photography Extension Tube
- User Manual
- Inspection Sheet
- Warranty Card
Mount
- Carrying Case
- AM3N Mount
- 2m USB2.0 cable (Type-B to Type-A)
- 1-meter USB 2.0 Cable (Type-C to Type-A)
- Performance Sheet (Periodic error test report)
- Quick Start Guide
- Hand Controller
- 2m Hand Controller Cable
- M6 Allen key
Tripod
Pier
Warranty
ZWO 2-Year Warranty
