New harmonic drive mount from MLAstro: The SAL-33

Astrophotography gear often comes from familiar big-name brands, so a new mount from a small solar-imaging company might raise some eyebrows. MLAstro, a Vietnam-based startup known for its cutting-edge spectroheliograph (narrowband solar imaging device), has taken a bold leap from capturing sunspots to tracking the entire night sky - I have one and it's amazing. As someone from around the Ozarks with a love for no-nonsense engineering, I find this move both surprising and refreshing. Their new creation, the MLAstro SAL-33 harmonic drive mount, arrives with an intriguing blend of common-sense design and high-tech innovation. It’s as if a folksy Mark Twain spirit guided an Einstein-level engineering project – the result is a mount that’s relatable yet profoundly advanced.

The SAL-33 is named for its 33-pound (~15 kg) payload capacity, and it represents MLAstro’s debut in the equatorial mount arena. What makes it stand out at first glance is the company’s solar-minded background. These folks cut their teeth designing equipment to photograph the Sun in exquisite detail, so they know a thing or two about precision and robustness. Now they’ve poured that know-how into a compact strain-wave gear equatorial mount. Let’s take a closer look at how the SAL-33’s solar heritage and innovative features come together to make it a potential game-changer for amateur astronomers and astrophotographers.

Editors note: The SAL-33 is currently not available. Pre-orders start soon, with a special discount of $100 off the first batch of customers.

Specs at a Glance

• Mount Type: Harmonic drive equatorial / alt-az dual-mode
• Load Capacity: Visual up to 15 kg (33 lbs) without CW, up to 20 kg (44 lbs) with 5 kg (11 lbs) CW; Imaging ~⅔ of visual load
• Slew Speed: Adjustable, up to 5°/s
• Drive System: Low-PE 17:100 harmonic drives (RA & DEC)
• Brakes: Physical brake (RA), back-EMF engine brake (DEC)
• Retains Pointing: Yes, retained after power cycle
• Firmware: Official OnStepX hardware, fully supported
• Open Source: Firmware & pinmap are fully open-source
• Build: 100% precision CNC-machined metal
• Alt-Az Base: MLAstro Zero-Shift design for stable polar alignment
• Connectivity: USB Type-B, WiFi (AP & Hotspot modes)
• Mount Head Weight: 5.6 kg (12.3 lbs)
• In the Box: Mount head only (PSU not included)
• Operating Temperature: –20 °C to +50 °C ambient
• Warranty: 1-year limited warranty
• Price: $1100 + shipping
• Optional Accessories: Hand controller - $120, counterwight bar - $30, P-200 mini pier extension - $149, Power supply - $50

Key Features and Specifications of the new harmonic drive mount from MLAstro: The SAL-33

Don’t let its small stature fool you – the SAL-33 packs a serious punch in terms of specs and build quality.

Here are the highlights of what this harmonic drive mount offers:

Load Capacity: The SAL-33 can carry up to 15 kg (33 lbs) of telescope and imaging gear for visual use without needing a counterweight. Add an optional 5 kg counterweight, and it supports 20 kg (44 lbs) MAX. In plain terms, that means it handles a mid-sized telescope (like a 8″ SCT or a hefty refractor) for visual observing, and even larger setups if you balance with a weight. For astrophotography, MLAstro takes a sensible approach and recommends about 70% of that load – roughly 10–11 kg (~24 lbs) – as the practical limit for best tracking performance. Sure, the mount can physically hold the full 15 kg, but if you push it to the max, you might start seeing your guiding accuracy wobble a bit. That kind of candid advice (often glossed over by others) shows MLAstro’s focus on real-world performance over marketing hype.

Mount Head Weight and Build: The mount head itself weighs a mere 5.6 kg (12.3 lbs). That’s carry-on luggage territory – highly portable for a mount of this capacity. It’s clear MLAstro had field use and travel in mind, much like other modern “mount-in-a-backpack” designs. Despite being lightweight, the SAL-33 is built like a tank where it counts. The chassis and components are precision CNC-machined metal, with micron-level tolerances on critical parts. There’s not a piece of flimsy plastic in the load-bearing structure. The company’s background in solar gear shines through here – they know people might set this mount under a harsh sun or a dewy night, so they made it tough and durable. In fact, the SAL-33 is finished with a silvery anodized coating rather than flashy paint. That’s not just for looks: the silver anodizing reflects sunlight and resists UV fading, keeping the mount cool and free from sun damage during daytime solar tracking. It won’t crack or peel over time like cheaper coatings might. This mount is literally engineered for the Sun – a nod to MLAstro’s roots and a boon for anyone who might use it for solar observing in addition to night sky imaging.

Harmonic Drive System: At the heart and soul of the SAL-33 are its strain wave gearboxes – one for each axis (RA and DEC). MLAstro didn’t cut corners here. They use custom high-quality 17:100 harmonic drive gearboxes in both axes. In more familiar terms, these are premium harmonic reducers with a 100:1 ratio, roughly the same type used in some high-end mounts on the market. The “17:100” spec refers to a size 17 harmonic drive with a 100:1 reduction gearing. The key takeaway is that these drives are built for low periodic error (PE) and long service life. Harmonic drives can vary widely in quality; inexpensive ones might exhibit large periodic tracking errors or wear out faster. MLAstro explicitly chose low-PE, tight-tolerance gearboxes – essentially the “good stuff” – to ensure smooth tracking. They’ve even hinted that their gear supplier is the same one a certain big “red” mount maker uses, but MLAstro opts for the top-grade units rather than bargain-bin versions. For the end user, this means the SAL-33 should track more reliably and give your autoguider an easier time correcting any residual error. In practice, MLAstro expects the mount to achieve sub-arcsecond guided RMS error when properly tuned, which is on par with the best in this class. It’s reassuring for those of us who obsess over tiny star shapes in long exposures.

Precision and Mechanics: The slew speed is adjustable, up to a brisk 4° per second at maximum. That’s plenty fast to zip from Polaris to Orion in a hurry when needed, yet you can dial it down for fine framing adjustments. The mount’s mechanics also boast a novel approach to polar alignment: MLAstro developed a “Zero-Shift” Alt-Az base for the SAL-33. If you’ve polar-aligned an equatorial mount before, you’ll know that tightening the alt-az adjustment bolts often nudges your alignment off (as if the mount has a mind of its own). MLAstro’s zero-shift design tackles this common annoyance. You keep the altitude and azimuth locking knobs snug while adjusting; a smooth fine-adjust knob moves the mount without backlash or sag. Once you have Polaris (or your pole star alignment) dialed in, you don’t need to crank down any locks that might shift it – it’s already locked, and there’s no shift. In plainer language: the SAL-33 won’t wander off target “like a drunk man” when you finish polar alignment. Anyone who’s done a midnight polar alignment dance will appreciate that stability. This kind of thoughtful engineering is typically found in much pricier mounts (if at all), so it’s a standout feature for the SAL-33.

Braking and Safety: One of the SAL-33’s hallmark features is its fail-safe braking system. The RA axis has a physical brake – a locking mechanism that engages to hold the position if power is lost or the motors are off. The DEC axis uses a form of electronic brake (back-EMF braking through the motor) to provide resistance when idle. Why does this matter? Imagine you’ve got a heavy telescope on the mount and someone trips over the power cable in the dark (let’s be honest, it happens to the best of us at 2 AM). On many strain-wave mounts without locks, the sudden loss of power could let the mount slip under imbalance, sending your expensive OTA swinging. Not here – the SAL-33’s RA lock will grab hold and prevent a sudden gravity-driven catastrophe. It’s peace of mind, especially if you run remote imaging sessions or outreach events where gear safety is paramount. The brake also helps when mounting or balancing your scope; you can engage it to keep the axis from flopping around as you tinker. It’s a simple addition that adds a layer of security and convenience.

Pointing Memory: Another creature comfort is that the SAL-33 remembers its pointing and alignment even after a power cycle. Inside the mount’s controller is non-volatile memory (a FRAM chip) that stores its alignment model and last coordinates. In practice, this means you can park the mount at the end of a session, power it off, and later power it on without losing your alignment synchronization. The mount will know where it’s pointed relative to the sky as long as it hasn’t been moved. If you’ve ever had to re-do a star alignment after an accidental shutdown or simply after a tea break, you’ll know what a time-saver this is. For portable use you’ll likely still align each night, but for an observatory setup or multi-night imaging from the same spot, this “pointing recall” is a welcome feature. It speaks to MLAstro’s software savvy and consideration for user experience – bridging a gap between fully encoder-equipped mounts and basic ones that start from scratch every time.

Connectivity and Control: Modern mounts need modern connectivity, and SAL-33 delivers there too. On the mount you’ll find a USB Type-B port for direct PC connection (or external hand-controllers), but you may not even need a cable: it has built-in Bluetooth and Wi-Fi. The Wi-Fi can operate in access point mode (where you connect your phone or laptop to the mount’s own network) or in station mode (where the mount joins your existing home or field router network). In plain speak, you can wirelessly connect to the SAL-33 with a smartphone, tablet, or computer to control it. This wireless capability makes for a cleaner setup – fewer cords to tangle in the dark. Imagine aligning or slewing the mount from your phone while you’re comfortably seated a few feet away; that’s easily done here. The SAL-33’s controller speaks standard telescope control protocols (thanks to its open-source brain, which we’ll discuss next), so it’s compatible with a wide array of astronomy software. Whether you prefer controlling your mount with SkySafari on an iPad, Stellarium or N.I.N.A. on a laptop, or any ASCOM/INDI client, you’re pretty much covered out of the box.

OnStepX: Open-Source Brainpower: Perhaps one of the most defining aspects of the SAL-33 is that it runs on OnStepX firmware. OnStep is a popular open-source telescope control system, and the “X” is its next-generation version. MLAstro’s SAL-33 isn’t just using OnStep in isolation; it’s actually the first production harmonic mount officially backed by the OnStepX project. The developers of OnStep have worked directly with MLAstro, even integrating the SAL-33’s pinout and specifics into the main OnStepX codebase. MLAstro in turn supports the project financially with a royalty for each unit sold. For the end user, this means two things: transparency and flexibility. The firmware inside the SAL-33 is open and user-updateable; you’re not locked into a closed ecosystem. You can tweak settings, load custom build options, and you benefit from the collective improvements the OnStep community makes over time. It’s somewhat analogous to using a phone with a stock Android OS versus a locked-down proprietary system. The SAL-33’s open approach will appeal to the tinkerers and those who value not being beholden to a single vendor for software updates. It also ensures long-term support – even if MLAstro moves on to new models years from now, the core software can still be maintained and enhanced by the community. And if you run into a bug or have a feature request, there’s a whole community and the original OnStep developers who could potentially address it, not just a customer support ticket system. This is a unique stance in a market where most mounts come with locked firmware. Despite being open-source, OnStepX is feature-rich and field-proven, supporting advanced functions like pointing models, plate solving integration, multi-star alignment, autoguiding, PEC (periodic error correction) training, and more. In short, the SAL-33 may be new hardware, but it’s powered by a very mature and capable brain.

Solar-Minded Design and Practical Details

One cannot discuss the SAL-33 without circling back to MLAstro’s solar imaging pedigree, because it influenced a lot of the design philosophy. The very look of the mount – its retro-industrial, silvery finish – is a direct result of being “engineered for the Sun.” Most mounts on the market are painted dark colors or black, which unfortunately means if you use them for solar observing (in direct sunlight), they can heat up like a frying pan. The SAL-33’s anodized aluminum not only gives it a distinctive appearance (some might affectionately call it a 1950s-industrial aesthetic), but it also stays cooler under the Sun and resists ultraviolet light. There are no plastic knobs or trim pieces that could crack after prolonged sun exposure. If you’re a solar observer or someone who leaves the mount set up in daylight, these are not trivial concerns – heat and UV can degrade equipment over time. MLAstro clearly thought about how their mount would fare pointing at our nearest star for hours on end, and built it accordingly. It’s a small design nuance that sets the SAL-33 apart as a true “solar-minded” mount. Even for strictly night-time users, knowing that your mount can handle a bit of sunshine and rough treatment is reassuring for overall durability.

Another practical detail: the SAL-33 is designed to be user-serviceable. The company states that most components (like the main board, stepper motors, drivers, and even the harmonic gearboxes) can be swapped out by the user if something goes wrong, with basic tools. They provide guidance and will ship replacement parts if needed, under warranty or even out of warranty. This is different from many mass-market mounts where a trip to the service center (or shipping the mount overseas) is required for repairs. The philosophy here seems to be “empower the user” – an ethos likely stemming from the open-source spirit. In practical terms, if a motor driver blows or a sensor wire comes loose after heavy use, you won’t be left high and dry. For those of us who live in places like the Ozarks or far from manufacturing hubs, the ability to fix things ourselves (with a little help from the maker) is a big plus. MLAstro has also set up forward logistics in various regions (the founder mentioned warehouses in the USA, UK, EU, etc.) so customers can send any major repair cases to a local address rather than navigating complex international shipping. It’s a thoughtful approach for a small company trying to support a global customer base.Of course, with any new mount, questions of quality control come to mind. MLAstro has indicated they are testing each harmonic gearbox for periodic error and even considering providing individual PE test reports with each unit (a practice more common among premium mount makers). They haven’t fully committed to that for every single mount due to logistics, but it shows the mindset: they are aiming for a premium experience at an affordable price. Speaking of price, the SAL-33 is slated at $1,100 USD retail, with an introductory price of $1,000 for early adopters (first 50 units). That is remarkably competitive – significantly less expensive than most mounts offering similar capacity and technology. It’s even within a stone’s throw of smaller harmonic mounts with lower capacity. We’ll compare directly to the ZWO models in a moment, but it’s safe to say MLAstro is aggressively positioning the SAL-33 as the value choice in the harmonic drive mount category. As a consumer, I find that exciting; as a reviewer, I temper it with the knowledge that true value will be proven by performance in the field. So far, the signs (and initial user reports) indicate MLAstro has something special on their hands.

SAL-33 versus ZWO AM3/AM5: How Does It Stack Up?

No mount exists in a vacuum (unless maybe you’re observing from space), so it’s natural to compare the SAL-33 to its peers. The most obvious competitors are the ZWO AM5 and AM3 mounts – popular strain-wave (harmonic drive) equatorial mounts that many astrophotographers have adopted for their portability and load capacity. ZWO essentially blazed the trail for affordable harmonic mounts in 2022 with the AM5, and later followed with the smaller AM3. Let’s break down how the new SAL-33 stands relative to these two in key areas:

Payload and Weight: The SAL-33 and ZWO AM5 are very close in load capacity. The AM5 is rated for about 13 kg (28–30 lbs) without a counterweight and up to 20 kg (44 lbs) with a counterweight – effectively the same class as SAL-33’s 15 kg / 20 kg specs. In practice, both mounts can handle a mid-sized imaging rig. Users have put an 8″ SCT or a 5″ refractor on the AM5 successfully, and one can expect SAL-33 to do the same. Meanwhile, the ZWO AM3 is a smaller sibling intended for lighter setups; it carries about 8 kg (17–18 lbs) unguided and around 13 kg (28 lbs) with a counterweight. So AM3 targets more of the “grab-and-go” visual or small refractor imaging crowd. The SAL-33 clearly plays in the higher league, going head-to-head with the AM5 in capacity, while offering almost double the payload of the AM3.

When it comes to the weight of the mount head, SAL-33 and AM5 are again similar: roughly 5.5–5.6 kg (about 12 lbs each). Both are quite portable – you can literally fit these mounts in a backpack for air travel, as many have done with the AM5. The AM3 is lighter at around 3.9 kg (~8.6 lbs), which is fantastic for portability, but that comes with its lower capacity. In essence, SAL-33 offers AM5-level muscle at what we expect to be a lower weight than many traditional mounts of similar capacity. All three mounts (SAL-33, AM5, AM3) are drastically lighter than equivalently rated classic worm-gear mounts, since harmonic drives don’t require heavy counterweights for moderate loads and have a high power-to-weight ratio. If you’re an itinerant astrophotographer hiking up a mountain or flying to a dark-sky site, any of these could be a godsend compared to lugging a 20–30 lb mount head and a stack of counterweights. The choice between them would come down to how heavy your telescope setup is and how much headroom you want.

Build Quality and Engineering: In terms of construction, all three mounts are made of metal and built to be sturdy, but there are differences in design philosophy. The SAL-33’s all-metal, CNC-machined approach with no plastic bitsstands out. ZWO’s AM series mounts are also robust, but they do have some plastic covers (for electronics, etc.) and a more modern curved aesthetic, whereas the SAL-33 has a utilitarian, bolted-panel look. Think of the SAL-33 as a sort of “functional industrial” design versus the sleeker consumer gadget vibe of the ZWOs. That might sound like a purely cosmetic distinction, but it reflects the companies’ backgrounds: MLAstro is coming from a hobbyist/DIY ethic (their roots in the DIY spectroheliograph community) and it shows in the mount’s serviceability and emphasis on function. ZWO, on the other hand, approaches mounts more like a conventional manufacturer – the units are not user-serviceable in any official sense, and tinkering inside them isn’t expected (and could void your warranty).

A very tangible engineering difference is the polar alignment base. The SAL-33’s Zero-Shift alt-az base is an innovation that really benefits users during polar alignment. Neither the ZWO AM5 nor AM3 feature anything quite like that. Typically, with the ZWO mounts (and most others), you’ll loosen an azimuth knob or an altitude bolt, adjust, then re-tighten to lock your polar alignment. Often there’s a tiny shift when you tighten – it’s practically a rite of passage in mount usage to overshoot a tad knowing the lock-down will pull you back. ZWO’s mounts have fairly decent alt-az adjustment mechanisms, but they aren’t zero-shift; you still have to gently lock them and hope your alignment stays put. So advantage SAL-33 here for making a normally tedious task much easier and repeatable. For imagers who set up and break down often, that’s a lot of saved time (and frustration).

Another engineering point: gearbox quality and periodic error. ZWO hasn’t publicly detailed what exact harmonic drive model they use in the AM5/AM3, but user experience shows the periodic error is moderate and smooth enough to guide out, typically on the order of tens of arcseconds peak-to-peak. MLAstro is explicitly using high-grade drives and touting low periodic error. If their claims hold, the SAL-33 might have a tracking edge if you measure periodic error or unguided performance. However, in practice most astrophotographers guide these mounts, so the difference might be marginal if both are guided well under a seeing-limited 0.5–1″ RMS. It will be interesting to see measured PE curves of the SAL-33 versus the ZWOs. One encouraging sign: MLAstro’s transparency about recommending 70% max load for imaging, which indicates they’re aiming to ensure the best tracking quality rather than just bragging about maximum torque. A mount that’s not over-stressed will perform better, so MLAstro’s conservative stance could mean the SAL-33 performs more consistently near its upper imaging load than an AM5 might if you really max it out. Essentially, MLAstro isn’t pushing the specs to 11 just for marketing – they’re giving realistic use guidelines, and that speaks to possibly better real-world performance within those guidelines.

Braking and Safety Features: This is one area where the SAL-33 clearly differentiates itself. The physical RA axis brake on the SAL-33 is a feature shared by the AM5 and AM3 include. But on the DEC axis, the ZWO mounts rely purely on the harmonic drive’s inherent friction and the motor holding torque to keep the telescope in position. If you power off an AM5/AM3, the mount DEC axis doesn’t automatically lock – it will stay mostly in place due to the tightness of the harmonic gear, but under enough imbalance or a nudge, it can move. Many users haven’t reported major issues with this, but there’s always that caution: secure your scope, don’t knock things, and if you have a heavy payload, consider using a counterweight for balance especially if running unpowered.

So MLAstro took the extra step of adding a fail-safe lock on RA and DEC, which means a powered-off SAL-33 is far less likely to shift unexpectedly. This is comforting if, say, you want to park the mount and turn it off when not in use without having to perfectly balance the load every time. The DEC axis on SAL-33 doesn’t have a physical lock but does use a magnetic braking technique to provide resistance.

Additionally, SAL-33’s ability to retain pointing info after power loss is something worth repeating here. With the ZWO mounts, if you accidentally cycle power, you’ll likely need to realign (or at least plate-solve to resync) because the mount won’t inherently remember where it was pointed. Unless you’re using an external system like the ASIAIR that keeps track, a power loss could mean “start from scratch” for alignment on an AM5/AM3. With SAL-33’s OnStep controller and FRAM memory, the mount itself stores the alignment and coordinates, so after a reboot it still knows its orientation. This could be a lifesaver if you have a brief outage or someone flips the wrong switch. It’s a subtle difference, but one that indicates MLAstro’s attention to detail in the user experience.

Software and Control Ecosystem: Here lies one of the biggest distinctions: Open-Source OnStepX vs ZWO’s Proprietary System. The SAL-33, running OnStepX, can be controlled by a wide range of third-party apps and programs. You could use the OnStep smartphone app, generic telescope controllers like SkySafari, desktop astronomy suites, or even issue LX200 or ASCOM commands directly – it’s all supported. The mount’s Wi-Fi and Bluetooth interfaces make it versatile in how you connect (USB if you prefer wired). OnStep itself has features for things like plate solving integration and even a web interface (if you connect via Wi-Fi, you can pull up a browser control page). This flexibility is fantastic for those who already have a preferred software setup or who like to tinker and automate. It’s also a plus for cross-platform users (Windows, Mac, Linux, Raspberry Pi – OnStep plays well with all via ASCOM or INDI drivers).

By contrast, ZWO’s AM5/AM3 come with a more closed but user-friendly ecosystem. There is the ZWO ASI Mount app (for mobile) which allows you to connect to the mount via Wi-Fi or Bluetooth and control it. The app provides a polished interface with features like an on-screen joystick, go-to catalogs, and integrated polar alignment (when used with ZWO’s ASIAIR or their app’s plate-solving). Many AM5 users pair the mount with the ZWO ASIAIR controller, which is a dedicated astro-computer that seamlessly integrates ZWO mounts and cameras for a turnkey imaging setup. With ASIAIR, tasks like polar alignment, go-to, guiding, and even image capture are all unified in one tablet interface. It’s very convenient – if you buy into the ZWO ecosystem. The AM mounts are also controllable via standard ASCOM drivers for PC use, so you’re not strictly locked to ASIAIR, but the tightest integration is indeed with ZWO’s own system.

So the decision here can come down to philosophy: Do you prefer a plug-and-play experience or a flexible, open one? SAL-33 with OnStep might require a bit more initial setup (for instance, connecting to its Wi-Fi and configuring your software of choice, learning the OnStep handset app or interface) whereas a ZWO AM5 used with an ASIAIR might feel more like using an appliance – it just works with minimal tinkering, especially if you’re already in that brand’s universe. However, the flip side is that SAL-33’s open approach means no proprietary lock-in. If you’re a fan of, say, using AstroBerry or N.I.N.A., or you want to script custom behavior, you can do that readily on SAL-33. Also, OnStep is constantly updated by a passionate community, so new features (like satellite tracking, advanced modeling, etc.) can become available without having to wait for a company firmware release. In fact, being officially supported by OnStepX means SAL-33 will likely be a testbed for new OnStep features – a nice position to be in.

One important note on polar alignment tools: The ZWO mounts notably do not have a built-in polar scope. They expect users to polar align via software (usually using the ASIAIR’s polar alignment routine or another electronic method). The SAL-33 also does not mention including a polar scope (which is becoming a trend to omit, to save weight and cost). Instead, SAL-33 users will likely use a polar alignment app or iterative alignment with software. OnStep has support for polar alignment via plate solving (through external software) or an assisted routine. In practice, both SAL-33 and AM5/AM3 users are going to use tools like SharpCap’s polar align, the ASIAIR method, or drift alignment if doing it old-school. So both are modern in that sense – don’t expect to squint through a tiny polar finderscope on either. However, SAL-33’s aforementioned zero-shift base will make the physical adjustment part of polar alignment less frustrating once the software tells you how much to adjust. With the ZWO, you might have to iterative tweak and re-check more if there’s slight movement on lock-down. It’s a small usability win for SAL-33 in this department.

Overall Performance (Real and Projected): How about tracking and guiding in actual use? ZWO’s AM5 has been out in the field for a couple of years now and has proven itself as a very capable mount, I can testify to this, I currently own two of them. Many astrophotographers (myself included) report getting 0.6–0.8 arcsecond RMS guiding routinely with the AM5, which yields pinpoint stars with mid-range focal lengths. The AM5 also has the ability to operate in Alt-Az mode (with firmware support) if one wanted to do casual visual observing without polar alignment, though most use it equatorially. The SAL-33 at present is purely an equatorial mount; OnStep can technically be configured for Alt-Az on some hardware, but SAL-33’s design is GEM-like and its firmware is tuned for EQ use. For visual observers, the difference is minor – you’d likely run all of these in equatorial mode on a tripod or pier for traditional tracking of the sky. If you do want Alt-Az operation for visual (no polar align needed, just level and go), the ZWO mounts have an edge by offering that as an option. It’s not a commonly used feature except at outreach events, but worth mentioning.

In terms of slewing noise and behavior, harmonic mounts including AM5 and presumably SAL-33 tend to have a characteristic electronic hum when slewing and are fairly quiet when tracking. They lack the long unwinding sound of traditional mounts during big position changes (because there’s no worm to rewind past backlash). I haven’t heard the SAL-33 in person yet, but if it’s anything like other strain-wave mounts, it should be relatively quiet – perhaps a soft whir or buzz at high speed. That’s good if you’re setting up in a quiet neighborhood or star party. ZWO’s mounts have been praised for being neighbor-friendly in volume; I would expect SAL-33 to be similar, given the steppers and gearboxes involved.

Price and Value Comparison: Price might be the SAL-33’s ace in the hole at just $1099 - $100 off for pre-order, making it $999 USD. With that said -due to US tarrifs, the shipping for the SAL-33 is going to set you back $190. Which makes the total cost of the mount around $1190 delivered.

The ZWO AM5 mount head typically retails around $1,999 (for just the mount, not including tripod or any accessories). Sometimes you’ll find bundle deals, but generally it’s near two grand for the head. The ZWO AM3 comes in lower – roughly around $1,199 to $1,299 for the mount head. That places the SAL-33’s $1,100 base price right in between, closer to the AM3 range despite having AM5-like capacity. This is a big deal for budget-conscious buyers. If SAL-33 performs as advertised, it means you could get essentially AM5 performance for nearly half the price of an AM5. That’s a huge win for consumers and could pressure the market overall. Of course, ZWO is an established brand with global distribution and a track record, whereas MLAstro is the new kid on the block (albeit with goodwill from their solar product). Some folks might be willing to pay a premium for the support network and proven reliability of ZWO. But there’s also a large segment of the astro community that loves to support innovative newcomers, especially when they deliver more bang for the buck. MLAstro’s direct-to-customer approach and open-source ethos might resonate strongly with that crowd. The competition here is healthy – ultimately pushing all makers to offer better value or unique features.

Support and Community: One cannot ignore the aspect of after-sales support and community when comparing. ZWO has a large user base, active forums, and generally decent customer service, though one critique that pops up is slow firmware updates or the closed nature of their software (if there’s a bug, you wait for ZWO to fix it, and they prioritize ASIAIR integration). MLAstro is smaller, but so far they have shown very responsive engagement with the community (the founder Minh is active on forums like Cloudy Nights answering questions). They emphasize customer service and have set up local return points as mentioned earlier. The OnStep community is another resource; if you have a question about how to do something with SAL-33’s software, the answer might already exist among the experienced OnStep users. In a sense, by buying an SAL-33, you’re joining both the MLAstro user family and the wider OnStep family. There’s a bit of a DIY flavor to that which some will love and others might shy away from. If you prefer a large company that you can call for support during business hours, ZWO (or iOptron or Sky-Watcher, etc.) may feel safer. If you enjoy interacting with the actual designer of your mount on a forum and being part of an evolving project, MLAstro offers that in spades at the moment.

MLAstro SAL-33 feature highlights: Zero-Shift Alt-Az base

Final Thoughts and Recommendations

It’s not every day that a new mount hits the scene and causes a stir, but the MLAstro SAL-33 has managed to do exactly that – and it hasn’t even shipped in volume yet at the time of writing. By leveraging a strong foundation in solar imaging tech and embracing open-source principles, MLAstro has crafted a harmonic drive mount that promises high-end performance at a mid-range price. The SAL-33 stands out with its innovative features like the zero-shift alignment base, the fail-safe RA brake, and OnStepX integration, all of which collectively show a deep understanding of what astrophotographers and observatory tinkerers value.

So, who should consider the SAL-33? If you’re an astrophotographer looking for a portable mount that can handle a serious imaging rig (within that 10–12 kg (22 - 26 lbs)  range) without requiring a heavy counterweight setup, the SAL-33 should be high on your list. It’s especially attractive for those who appreciate openness – you get full control of the system and the reassurance that you’re not locked out of your own gear’s software. The SAL-33 would pair nicely with a medium-sized refractor or reflector for imaging, and its light weight means you can take it to a dark sky site as easily as you’d take a smaller star tracker. The mount’s precision and low periodic error aims to keep your long exposures on track, and the honest load recommendations mean you can trust it to perform within those limits. The price point makes it quite compelling as an alternative to more expensive options – you might save money that can go towards a better camera or telescope (always a plus in this hobby, where the shopping list never ends).

If you’re primarily a visual observer, the SAL-33 is still a strong contender. It can hold a 15 kg telescope without counterweights, which covers a wide range of popular scopes (for example, an 11″ SCT OTA weighs around 12–13 kg, which the SAL-33 could handle for visual with perhaps a small counterweight for stability). The GoTo performance and tracking accuracy will mean objects stay in your eyepiece field for long periods, and you won’t need to do constant nudging. The ability to quickly set up and tear down, aided by that easy polar alignment base, means more observing time and less fiddling time – something anyone can appreciate on a cold night. However, visual users might miss having a dedicated hand controller if they don’t want to use a phone or tablet to slew around. It’s worth noting you could add a simple wired hand paddle to OnStep if needed, or just use a small tablet as your “virtual hand controller” with many free planetarium apps. In the Ozarks or anywhere under dark country skies, I imagine setting this mount up with a tablet in one hand and a sweet tea in the other, slewing to the Andromeda Galaxy with a tap, and enjoying the view without a hitch.

Comparing to the ZWO AM5 and AM3, it boils down to your specific needs:

If you need maximum portability and your setup is lightweight (under ~8 kg imaging), the ZWO AM3 is an option due to its even lighter mount head. But you trade away capacity and some of SAL-33’s unique features.

If you want a proven track record and tight integration with the ZWO ecosystem (for example, you already use an ASIAIR and ZWO cameras and want everything to mesh effortlessly), the ZWO AM5 remains a solid, albeit pricier, choice. It’s a mature product with many satisfied users. Just be ready to invest more, and perhaps consider a counterweight for heavier loads despite the “no counterweight needed” marketing – same as SAL-33’s realistic approach.

The MLAstro SAL-33, on the other hand, offers an enticing blend of high capacity, moderate cost, and advanced features. It’s ideal for the user who likes to get under the hood (figuratively) and appreciates thoughtful engineering. The open-source firmware and the company’s hands-on support might actually make it easier to resolve issues or customize behavior compared to a closed system.

One could say the SAL-33 is for the astro-geek who has a bit of rebel in them – not content to just take what the big companies offer, but eager to try something new that’s backed by community-driven tech. It’s kind of poetic that a company born from solar astronomy innovation is now challenging established mount manufacturers; it reminds me of an old truism: the rising sun illuminates new paths. MLAstro has risen from the specialized niche of solar imaging to shine in the broader astro market with this mount.

Only time (and lots of night sky hours) will tell if the SAL-33 truly lives up to its promise, but the initial impression is very positive. As an astronomy enthusiast, I’m thrilled to see this competition because it means better gear for everyone. And as someone with a bit of Ozarks plain-speaking sensibility, I appreciate MLAstro’s upfront approach – they’re not selling snake oil, just a mount that does what it says on the tin and then some.

Bottom line: The MLAstro SAL-33 looks to be a phenomenal harmonic drive mount that punches well above its weight. It brings some new twists to the strain-wave mount game, all while keeping costs reasonable. If you’re in the market for a portable yet powerful astrophotography mount, the SAL-33 absolutely deserves a spot on your shortlist alongside the likes of ZWO’s offerings. It’s a great time to be into astronomy gear – choices are expanding, and innovation is coming from unexpected places. Whether you’re capturing narrowband images of the Sun or photographing distant galaxies at midnight, mounts like the SAL-33 are bridging those worlds with a combination of brains, brawn, and a little bit of that inventive spirit that makes this hobby so rewarding. As soon as we get our hands on one of the new mounts from MLAstro, we'll be sure to kick the tires and report back here on ScopeTrader.

MLAstro SAL-33 Ordering