ZWO FF90 APO Refractor w/ AM3N Astrophotography Bundle

The 90mm APO & AM3N Bundle: A Complete Imaging Platform

This bundle is engineered as a cohesive solution for portable deep-sky astrophotography. It pairs the ZWO FF90 APO's full-frame optical performance with the high payload-to-weight ratio of the AM3N harmonic mount. The system is completed by the lightweight TC40 carbon fiber tripod and PE160 pier extension, creating a stable platform that is easy to transport and quick to set up at a dark-sky site.

The components are designed to work together. The telescope's 9.97 lb. weight fits comfortably within the mount's 17.64 lb. capacity, the pier extension ensures the telescope clears the tripod legs when pointing high, and the mount's versatile control options integrate directly with ZWO's ASIAIR ecosystem or standard PC software.

AM3N Payload: A 7.67 lb. Margin for the 9.97 lb. FF90 APO

The ZWO AM3N mount is rated to carry 17.64 lb. without a counterweight. With the FF90 APO weighing 9.97 lb. fully dressed with its handle, rings, and dovetail, you have a 7.67 lb. margin for your camera, guide scope, filter wheel, and other accessories. This generous headroom ensures the mount operates well within its design limits, which is critical for maintaining tracking accuracy during long exposures.

By eliminating the need for counterweights, the total system weight is significantly reduced, enhancing portability. The combination of a 9.04 lb. mount head and a 9.97 lb. telescope creates a powerful imaging rig that remains manageable for a single person to carry and assemble in the field.

FF90 Optics: A 90mm f/6.8 Self-Flattening Quadruplet

The optical core of this system is the FF90's 90mm aperture, 609mm focal length (f/6.8) quadruplet lens assembly. This four-element, air-spaced design is "self-flattening," meaning it corrects for field curvature internally without requiring a separate field flattener accessory. This simplifies your imaging train and eliminates complex back-focus calculations.

One of the four elements is made from Extra-Low Dispersion (ED) glass to minimize chromatic aberration, resulting in sharp stars with well-controlled color. At f/6.8, the telescope gathers light efficiently, allowing you to capture deep signal on faint targets like the Triangulum Galaxy (M33) with shorter sub-exposure times than a slower instrument would need.

A 44mm Image Circle for Full-Frame Astrophotography

The FF90 APO is engineered to produce a fully illuminated and corrected 44mm image circle. This is large enough to cover full-frame sensors (36x24mm), allowing you to take full advantage of their wide fields of view. You can pair this telescope with DSLRs, mirrorless cameras, or dedicated full-frame astronomy cameras without vignetting or distorted stars at the edge of the frame.

Because the field is natively flat, you simply attach your camera and focus. The focuser provides a focus range of 45mm to 75mm from the M48x0.75 thread, accommodating most cameras, filter wheels, and off-axis guiders without needing a large collection of extension tubes.

The 3" Dual-Speed Rack & Pinion Focuser

To support heavy, full-frame imaging trains, the FF90 APO is equipped with a rigid 3" rack and pinion focuser. Its dual-speed 1:10 fine-focus knob allows for precise adjustments, which are essential for achieving critical focus with modern high-resolution sensors. The focuser body also includes pre-drilled mounting holes for a ZWO EAF (Electronic Automatic Focuser, sold separately) for automated focusing routines.

• 360° Rotator: A built-in rotator with a degree scale allows you to frame your target without loosening the camera.
• Standard Connections: The included photography extension tube provides standard M54x0.75 and M48x0.75 male threads for direct connection to most astronomy cameras and T-rings.
• Filter Integration: The M48 adapter has built-in threads for mounting a standard 2" filter inside the imaging train.

AM3N Strain-Wave Drive: <±15" Periodic Error Without Counterweights

The AM3N mount uses a strain-wave gear system with a 300:1 reduction ratio, delivering high torque and smooth tracking from a compact, 9.04 lb. body. This design eliminates the need for counterweights for payloads up to 17.64 lb. Every AM3N unit is tested at the factory and ships with a performance sheet verifying its periodic error is less than ±15 arcseconds over its 288-second cycle.

This high native tracking accuracy minimizes the work your autoguider has to do, resulting in rounder stars during long exposures. For even higher precision, an ST4 autoguider port is available for connecting a guide camera.

Dual-Mode Control from 0° to 90° Latitude

The AM3N is engineered for both equatorial (EQ) and alt-azimuth (Alt-Az) operation, switchable via the included hand controller. Use EQ mode for serious, polar-aligned astrophotography, or switch to Alt-Az for quick, simple GoTo visual observing sessions. The mount's mechanical design supports a full latitude range of 0° to 90°, making it usable anywhere on Earth.

Control is managed through multiple interfaces. The mount has integrated WiFi and Bluetooth for wireless connection to ZWO's ASI Mount and SkyAtlas mobile apps. It is fully compatible with the ASIAIR platform and supports ASCOM and INDI drivers for control from PC-based software like NINA or SGP via its USB port.

The 5.07 lb. TC40 Tripod and 160mm Pier Extension

The foundation of this bundle is the ZWO TC40 tripod, which provides stability from a frame weighing only 5.07 lb. Its carbon fiber legs have a maximum diameter of 1.5" and dampen vibrations effectively, while supporting a 110.23 lb. load. The adjustable height range of 18.5" to 31.49" allows you to level the system on uneven terrain.

The included PE160 Pier Extension adds a critical 6.30" (160mm) of height between the tripod and the mount head. This clearance prevents the 513mm-long FF90 APO or your attached camera from colliding with the tripod legs when tracking objects high in the sky, especially past the meridian.

12V @ 3A Power System with Power-Off Brake Protection

The AM3N mount operates on a standard 12V DC power supply and requires at least 3A of current. It features a critical safety system: a power-off brake on the Right Ascension axis. If power is accidentally lost, the brake engages instantly to stop the telescope from swinging, protecting your optics and camera from damage.

For cleaner cable management, the dovetail saddle integrates a 12V DC power output and a Type-C USB port. This allows you to power an ASIAIR, camera, or other accessories directly from the mount head, reducing the risk of cables snagging as the mount slews.

Imaging at 609mm: Framing the Andromeda Galaxy (M31)

The FF90's 609mm focal length provides a useful image scale for a wide range of deep-sky objects. When paired with a full-frame sensor, the field of view is approximately 3.4° x 2.3°. This is wide enough to capture the entirety of the Andromeda Galaxy (M31) and its satellite galaxies M32 and M110 in a single frame.

For smaller targets, the 90mm aperture resolves fine detail. You can effectively frame objects like the Whirlpool Galaxy (M51) or the Eagle Nebula (M16), capturing both the bright core and fainter outer structures. The system's portability makes it an excellent choice for traveling to dark sites to image large, dim targets like the North America Nebula (NGC 7000).

ZWO FF90 vs. FF70: 65% More Light-Gathering Power

When choosing between ZWO's quadruplet refractors, the FF90 offers significant advantages in light grasp and image scale over the smaller FF70. While the FF70 is lighter and provides a wider true field, the FF90 is better suited to resolving finer detail and capturing fainter objects.

• Light Gathering: The 90mm objective of the FF90 gathers approximately 65% more light than a 70mm objective. This translates directly to shorter exposure times or the ability to record fainter nebulosity and galaxy details.
• Image Scale: With a 609mm focal length, the FF90 provides more magnification than the FF70. This makes it better suited for framing small to medium-sized deep-sky objects where resolution is key.
• Weight Trade-off: The trade-off for increased aperture is weight. The FF90 OTA weighs 9.97 lb. fully configured, making it a good match for the AM3N's 17.64 lb. counterweight-free capacity.

First Night Setup with the FF90 and AM3N Bundle

Setting up this bundle is designed to be straightforward. Start by extending the TC40 tripod legs and leveling the head. Attach the PE160 pier extension, followed by the AM3N mount head. With the mount in equatorial mode, adjust its latitude to match your location using the 0°-90° scale.

Next, attach the 230mm Vixen-style dovetail of the FF90 APO to the mount's dual saddle and secure it. Because the mount does not require precise balance, you can simply center the telescope on the saddle. After attaching your camera, power on the mount and perform your polar alignment routine using polar alignment software such as the ASIAIR app. Once aligned, you are ready to use the hand controller or app to slew to your first target and begin focusing.