An in depth review of ZWO AM5N Harmonic Mount by Astromaniac Magazine — *The 2nd generation of ZWO’s Harmonic Mounts was released in 2024.*

Off the back of the very successful ZWO’s first ever harmonic mount, AM5 that proved to be very popular, in 2024 ZWO announed an enhanced version of that, AM5N. This was designed specifically for astrophotography, offering an impressive low periodic error, stable transmission, and high torque output. like its predecessor, each mount is tested to ensure a periodic error within ±10 arcseconds, guaranteeing its performance.

Advantages of the new AM5N over the first-gen AM5 mount:

An extra 3KG payload.
Considerably better azimuth and altitude adjustment knobs for easier polar aligment.
DC power port and USB-C port on the saddle for better cable management.
Slightly more streamlined user-interface and design.

*Harmonic drive mounts like AM5N have a more compact design compared to the traditional mounts.*

What are Harmonic Drive mounts?

Harmonic drive mounts are a type of advanced mechanical system commonly used in precision applications, including astrophotography and robotics. These mounts rely on a harmonic drive (also known as a strain wave gear) to deliver smooth, precise, and backlash-free motion.

While their guiding accuracy may slightly trail premium traditional mounts, the difference is often negligible for most users. Unlike traditional mounts, they don’t require meticulous balancing, simplifying the setup process significantly. However, they rely heavily on a process called Guiding for better tracking.

Though typically more expensive than traditional mounts, their portability and ease of use make harmonic drive mounts a worthwhile investment for amateur and more avid astrophotographers, particularly those on the go.

How Harmonic Drive Works

Core Components:
- Wave Generator: An elliptical part that rotates within the gear system, deforming the flex spline.
- Flex Spline: A thin-walled, flexible gear that engages with the circular spline.
- Circular Spline: A rigid, outer gear with internal teeth.
Mechanism:
- The wave generator rotates, deforming the flex spline and causing its teeth to engage with the circular spline at specific points.
- As the flex spline rotates, the difference in the number of teeth between it and the circular spline produces a reduction in speed while maintaining high torque and precision.

Advantages in Harmonic Drive Mounts:

High Precision: The harmonic drive provides exceptional positional accuracy, making it ideal for tracking celestial objects during long-exposure astrophotography.
Zero Backlash: This system eliminates gear backlash, ensuring smoother and more consistent movement compared to traditional worm gear mounts.
Compact Design: Harmonic drive mounts are lightweight and compact, despite their ability to handle substantial payloads.
Durability: The mechanism is highly durable and can withstand wear over time, requiring minimal maintenance.

Relevance in Astrophotography:

Harmonic drive mounts like the ZWO AM5N are particularly popular among astrophotographers because they excel in portability and precision. Their ability to perform well without counterweights simplifies setup and makes them travel-friendly. Moreover, the lack of backlash ensures pinpoint accuracy for guiding and imaging deep-sky objects, even under demanding conditions.

AM5N’s Performance:

The ZWO AM5N excels in performance, particularly in tracking and guiding accuracy. The mount boasts a weight capacity of up to 13kg (or 20kg with a counterweight), making it suitable for a wide range of telescopes and imaging setups. Despite its compact size and portability, the AM5N delivers precise tracking thanks to its harmonic drive system.

Astrophotographers will appreciate its low periodic error, which reduces the need for aggressive guiding corrections. Additionally, its guiding accuracy is exceptional, with root mean square (RMS) errors consistently below 0.5 arcseconds when paired with a high-quality guiding system.

ZWO AM5N performance on PHD2 | payload of 10.3 KG without counterweight

*As well as The ZWO carbon fiber tripod, AM5N also can be used with 1.75” steel tripods from iOptron, Sky-watcher, and with the 2 inch tripod for Celestron Advanced VX mount.*

Optional add-ons you might want to consider:

The carbon-fibre tripod, pier extension and the counterweight bar are not included in the base package. All of these accessories in fact are a must, unless you already have them from your previous mounts.

The tripod is very lighweight, which might not feel super sturdy and stable for larger telescopes. But luckily it comes with a weight sandbag which allows you to load it with anything to pull your setup downwards. As for the pier extention, unless you have a very small telescope, we strongly recommend getting the pier extention in order to make sure the back of the telescope and camera won’t hit the tripod when you point your telescope upwards.

The counterweight bar is only needed if your setup is heavier than 15KG. Adding a counterweight will allow for an additional 5KG of payload (a total payload of 20KG, excluding the counterweight)

SkyAtlas app:

One of the key selling popints of ZWO AM5N is its dedicated app SkyAtlas, which allows you not only to connect to the amount and contril it, but also point your telescope to any target you like via a very well designed sky atlas app that connects to the mount hassle-free.

The AM5N is fully integrated with ZWO’s ASIAIR platform, providing a seamless experience for astrophotographers. Through the ASIAIR mobile app, users can:

Perform polar alignment electronically, simplifying a traditionally complex process.
Control the mount for slewing, guiding, and tracking.
Sync with ZWO cameras, focusers, and filter wheels for an integrated workflow.

The AM5N offers Wi-Fi and USB connectivity, enabling users to operate the mount remotely or via a wired connection to a laptop. This makes it highly versatile, accommodating both mobile and desktop-based workflows.

Things we like about ZWO AM5N mount:

Leighweight, small and relatively portable.
Convenient carrying box with plenty of space for accessories.
Works perfectly out of the box.
Seamless wireless control via ZWO’s SkyAtlas control app.
Speedy polar alignment thanks to easy to us az/alt knobs.
Power pass through feature in the saddle.

Things that could be improved:

By the time you add all the necessary accessories (tripod, counterweight bar and pier extention, power adapter) it can get pretty expensive (up to £3000). Although it is still in line with the pricing of its competitors and in some cases it is even cheaper. Plus, users have the option to choose the cheaper ZWO mount, AM3 which is slightly smaller and has a payload of 8kg to 13kg.

ZWO AM5N Harmonic Equatorial Mount: A New Era Begins!