ZWO FF131 APO Refractor w/ AM7 Astrophotography Bundle

The ZWO FF131 & AM7 Bundle: A 4-Part Astrophotography System

This bundle integrates four key ZWO components into a single, cohesive astrophotography system designed for stability, optical correction, and ease of use. It includes the FF131 APO optical tube, the AM7 strain-wave mount, the lightweight TC40 carbon fiber tripod, and the PE200 pier extension. The result is a turnkey solution for imagers who want to use full-frame cameras without needing to research and match individual components.

By providing the telescope, mount, and support system in one package, ZWO has engineered a complete rig where every part is matched to the others. The system is built around the AM7's ability to carry the 20.72 lb. FF131 OTA without counterweights, creating a powerful yet streamlined setup for capturing deep-sky objects at a 983mm focal length.

The AM7 Mount & FF131 OTA: A 44 lb Capacity for the 20.72 lb Telescope

The core of this bundle is the pairing of the AM7 mount with the FF131 OTA. The telescope, fully dressed with its included handle, mounting rings, and 300mm Losmandy-style dovetail, weighs 20.72 lb. The AM7 mount's native payload capacity is 44 lb. without requiring any counterweights.

This leaves a substantial 23 lb. margin for your imaging train, including a full-frame camera, filter wheel, off-axis guider, and electronic focuser. This generous headroom ensures the strain-wave drive operates well within its optimal range, delivering precise tracking without being stressed by a load near its limit.

FF131 APO Optics: A 131mm f/7.5 Self-Flattening Quadruplet

The FF131 APO is built on a 4-element, air-spaced apochromatic optical design. With a 131mm aperture and a 983mm focal length, the f/7.5 system provides an image scale well-suited for resolving details in medium-sized galaxies and nebulae. The quadruplet lens arrangement is engineered to correct for optical aberrations across the visual spectrum without needing a separate accessory lens.

This design minimizes chromatic aberration, or color fringing, ensuring that stars appear as sharp, color-pure points of light. By integrating the field-flattening element directly into the main optical train, ZWO simplifies the imaging setup and eliminates a potential source of flexure or tilt.

The 44mm Image Circle: Native Full-Frame Correction

A key feature of the FF131 APO is its self-flattening design that produces a 44mm corrected image circle. This is large enough to fully illuminate full-frame sensors (typically 43.3mm diagonal), providing sharp, pinpoint stars from the center to the corners of your frame. You can take full advantage of large-format CMOS or DSLR cameras without vignetting or distorted stars at the edges.

Because the field correction is native to the optics, you do not need an external field flattener. This removes the complexity of calculating and setting a precise back focus distance. Your imaging train simply needs to achieve focus within a generous 42mm to 73mm range from the M48x0.75 adapter thread.

Mechanical Design: A 3" Dual-Speed Focuser and 20.72 lb. OTA

To support heavy imaging loads, the FF131 APO is equipped with a rigid 3" rack-and-pinion focuser. This design prevents slippage and flexure, even with a large camera and filter wheel attached. The focuser features a dual-speed 1:10 fine adjustment knob for achieving critical focus, and a built-in 360° rotator allows for precise framing of your target without rotating the entire camera.

• Focuser Travel: Provides 31mm of travel for a wide range of accessories.
• Retracted Length: The telescope measures 878mm with the dew shield retracted, making it more manageable for transport.
• Mounting Hardware: Includes a 300mm Losmandy-style dovetail plate and two findershoes for attaching a guide scope or other accessories.

AM7 Strain-Wave Drive: <±10" PE and a 44 lb Counterweight-Free Payload

The ZWO AM7 mount uses a strain-wave gear system and synchronous belt drive to carry a 44 lb. payload without counterweights, while the mount head itself weighs only 14.9 lb. For heavier setups, adding a counterweight (sold separately) to the included shaft increases the capacity to 66 lb. The drive delivers precise tracking with a native periodic error of less than ±10 arcseconds over its 288-second cycle.

Every AM7 mount is tested before shipping and includes its own unique periodic error report. The RA axis also features a power-off brake, which automatically engages during a power failure to prevent the telescope from swinging and protect your equipment.

AM7 Control: Dual-Mode Operation from 0° to 90° Latitude

The AM7 operates in both German Equatorial mode for precise long-exposure imaging and Alt-Azimuth mode for simple visual observing. With a latitude adjustment range of 0° to 90°, the mount can be polar aligned and used anywhere on Earth. Control is flexible, with options for wired or wireless operation.

• Hand Controller: The included hand controller provides direct control and acts as a Wi-Fi hotspot for connecting via the SkyAtlas mobile app.
• Wireless & Wired Control: Connect via Wi-Fi, Bluetooth, or USB to control the mount with ASIAIR, ASCOM, or INDI drivers.
• Cable Management: USB-C and 12V DC power ports on the saddle plate reduce cable drag by allowing you to power your camera and accessories through the mount itself.

Support System: The 5.07 lb TC40 Tripod and 200mm PE200 Pier

The foundation of the bundle is the ZWO TC40 Carbon Fiber Tripod and PE200 Pier Extension. The TC40 tripod weighs only 5.07 lb. but has a tested load capacity of 110.23 lb., providing a rigid, vibration-dampening base that is easy to transport. Its height adjusts from 18.5" to 31.49".

The included PE200 pier extension adds 200mm of vertical clearance between the tripod and the AM7 mount. This is critical for preventing the 878mm-long FF131 OTA from colliding with the tripod legs during an automated meridian flip, enabling safe, unattended imaging sessions that track objects across the entire sky.

ZWO AM7 vs. AM5N: Choosing Based on Payload

While both the AM7 and its smaller sibling, the AM5N, use the same core strain-wave drive technology, the AM7 is built for heavier instrument loads. The primary difference is payload capacity, which makes the AM7 the correct choice for an optical tube of the FF131's size and weight.

• ZWO AM5N Advantage: The AM5N is more portable, with a lighter mount head and a 33 lb. capacity (without counterweights), which suits smaller refractors and travel setups.
• ZWO AM7 Advantage: The AM7 provides a higher 44 lb. native capacity (66 lb. with a counterweight), offering the stability and margin required for the 20.72 lb. FF131 plus a heavy, full-frame imaging train.

Your First Night With the FF131 & AM7 Bundle: From Setup to First Light

Setting up this integrated system is a streamlined process. Start by extending the TC40 tripod legs and attaching the PE200 pier, followed by the AM7 mount head. Mount the 20.72 lb. FF131 OTA onto the dual Losmandy/Vixen saddle; no balancing is required thanks to the strain-wave drive.

After connecting the 12V, 5A power supply, use your camera and preferred software (like an ASIAIR) to perform a software-assisted polar alignment. Attach your camera to the focuser's M48 thread, point to a bright star, and use the 1:10 fine focus knob to achieve a sharp image. You are now ready to slew to your first deep-sky target and begin imaging.