Originally launched a decade ago, the ZWO ASI174MM is a planetary astrophotography camera — something you insert into the eyepiece of a telescope to take images and video of deep-sky objects, planets, the moon and the sun. This one is very much geared towards the latter, with solar and lunar imaging its goal.

At first glance, the specification looks simple: a 2.3MP monochrome Sony IMX174 sensor, 5.86µm pixels, USB 3.0 connectivity and a compact red aluminum body. The important details are the sensor size, speed and global shutter. For lunar and solar imaging, where you often want to capture large areas in high frame rate videos and freeze split-seconds of steady “seeing” — when turbulence in Earth’s atmosphere doesn’t degrade an image of an astronomical object — those traits matter more than headline megapixels.

The ASI174MM is especially attractive for solar imaging with an H-alpha telescope — a filter that blocks all wavelengths of light other than H-alpha, which is emitted by hydrogen atoms. That’s because its 5.86 μm pixels match the focal ratios typical of solar telescopes, yielding sharp, efficient detail. Its relatively large sensor can cover more of the solar disc than many small planetary cameras, while its high frame rate supports the usual lucky-imaging workflow of capturing video, selecting the best frames and stacking them for sharper images.

ZWO ASI174MM astronomy camera: Design

• Compact aluminum camera body
• USB 3.0 and ST4 guide port included
• Useful adapter bundle

The ZWO ASI174MM has a compact, lightweight and practical design that’s ideal for use as a camera attached to a telescope. Its small cylindrical aluminum body adds very little strain to a focuser, solar diagonal or off-axis guider, which is particularly useful when working with solar telescopes.

Usefully, the camera includes a high-speed USB 3.0 connection, which is important because the ASI174MM’s main strength is capturing and transferring many video frames very quickly. It can also be used over USB 2.0, but doing so gives up much of the performance that makes the camera appealing in the first place.

An ST4 guide port adds extra flexibility. Although the ASI174MM is primarily sold as a planetary camera, it can also be used as a guide camera (mounted on top of a main imaging scope to capture a wide field of view), especially with off-axis guiders (a device that sits between a main camera and the telescope to precisely track stars), where the larger sensor helps find guide stars more easily than smaller-chip models.

ZWO ASI174MM astronomy camera: Performance

• Excellent for solar and lunar video capture
• Global shutter is a real advantage
• Large pixels favor longer focal lengths

The ASI174MM’s combination of a relatively large 1/1.2-inch sensor, 5.86µm pixels, and fast video capture makes it particularly well-suited to imaging the sun and moon. Compared with planetary cameras built around smaller sensors, it records a considerably larger area of the telescope’s field of view, reducing the number of panels needed for mosaics and making it easier to locate and frame a target.

That larger sensor is especially useful for solar imaging, which is what we tested it with. The exact field of view depends on the telescope’s focal length, but the ASI174MM can capture larger active regions — and, with some setups, most or all of the solar disc — without immediately requiring a mosaic. For example, we tested it with the Sky-Watcher Heliostar 76Ha solar telescope, for which it is a natural match, where prominences, filaments, sunspots and rapidly changing structures on the solar surface need to be recorded at high speed.

The camera’s global shutter is another advantage for solar imagers. A rolling shutter (the standard choice for deep-sky imaging) records an image progressively, one row of pixels at a time, to produce a low-noise, high-dynamic-range image. However, atmospheric turbulence, which slightly shifts the image, can cause distortion. A global shutter exposes the entire sensor simultaneously, helping the ASI174MM preserve the shape of solar and lunar features more accurately from frame to frame.

High-speed capture also supports lucky imaging. Instead of trying to produce one perfect exposure, the camera records thousands of short exposures in rapid succession. Software then identifies and stacks the sharpest frames — the brief instants when Earth’s turbulent atmosphere becomes relatively steady.

While it’s ideal for solar imaging, the ASI174MM is much less convincing as a conventional deep-sky camera. Long exposures can reveal pronounced amp glow towards one side of the frame, while the uncooled sensor becomes increasingly noisy as exposure times increase. Calibration with dark frames can reduce these effects, but it adds complexity and cannot turn the ASI174MM into a modern cooled deep-sky camera. It can be used for short-exposure imaging, guiding and some specialist applications, but solar, lunar and planetary video remain its natural strengths.

ZWO ASI174MM astronomy camera: Functionality

• Captures good data
• ZWO software works well
• Little guidance available

The ASI174MM fits neatly into the established workflow for solar, lunar and planetary imaging: capture a high-speed video, identify the sharpest frames, align and stack them, then sharpen and process the image. Its fast USB 3.0 connection enables high data transfer rates, while region-of-interest controls allow the user to record only a selected portion of the sensor. Reducing the size of the recorded area can substantially increase the frame rate, which is particularly useful when imaging an individual sunspot.

Several free applications can control the camera and record these videos, including SharpCap and FireCapture. AutoStakkert! is widely used to analyze, align and stack solar, lunar and planetary frames, while programs such as ImPPG, RegiStax, Siril, Adobe Photoshop and GIMP can be used for sharpening, contrast adjustment and final processing. Windows users have the widest choice of third-party astronomy software.

However, ZWO also provides its own free ASIStudio software suite. For the ASI174MM, the most relevant applications are ASICap, which controls the camera and records lossless SER or AVI video, and ASIVideoStack, which analyses and stacks the resulting frames (and can also be used for post-processing). ASIStudio is available for both Windows and macOS.

The basic capture process is straightforward. After connecting the ASI174MM to ASICap, exposure time and gain are adjusted until the brightest areas of the sun or moon remain below saturation. Because this is a monochrome camera, the live view can be shown either in grayscale or with false color applied for easier viewing. A video containing around 1,000 to 3,000 frames is then recorded, though the ideal number depends on the target, seeing conditions and available storage.

Storage requirements are significant. Uncompressed high-frame-rate video from the full sensor can consume several gigabytes in a matter of seconds, so a fast computer, a USB 3.0 connection and plenty of free drive space are essential.

Once a video is loaded into ASIVideoStack, the software can assess frame quality, align the image and combine a chosen percentage of the sharpest frames. The finished stack can be exported in formats including JPEG and FITS. JPEG is convenient for immediate sharing, but FITS preserves more of the original image data and is better suited to serious post-processing.

The workflow is functional rather than polished. There is relatively little guidance for beginners and obtaining the best results requires experimentation with exposure, gain, frame rate, focus, stacking percentages and sharpening settings. It can take many attempts to determine which combination works best with a particular telescope and observing conditions. For that reason, it’s wise to archive the video files, which can be revisited and processed later as processing skills/software improves.

How we tested the ZWO ASI174MM

We tested the ZWO ASI174MM planetary camera for two weeks and used it in conjunction with the Skywatcher HelioStar 76mm solar telescope and Solar Quest mount to image the sun in H-Alpha (Hα).

Should I buy the ZWO ASI174MM?

Buy the ZWO ASI174MM if your main targets are the sun and moon, especially if you want a monochrome camera with a larger-than-average sensor, fast frame rates and a global shutter. It remains particularly suited for H-alpha solar imaging, where monochrome capture, speed and sensor area matter.

If this product isn’t for you

If you want a cheaper first planetary camera, a smaller-sensor ZWO ASI120-series-style camera may be enough for basic lunar, planetary and guiding use, though it will not offer the same field of view.

If you want a more modern planetary camera, look at newer monochrome planetary models like the ZWO ASI585MM with lower read noise, smaller pixels or higher resolution, depending on your telescope’s focal length.

If your goal is deep-sky imaging, a cooled astronomy camera is a better choice than the ASI174MM. We have reviewed the ZWO ASI533MC Pro and the ASI183MC Pro and gave both of them nothing less than four and a half stars for beautiful deep-sky astrophotography.

Finding the sun sounds easy, right? Many people think of the sun as big and bright, but it’s actually rather small in the sky — it’s got an angular diameter of just half a degree, in fact, the same as the moon. Put an all-important solar filter on a telescope, and you’re left with the challenge of finding a tiny orange or white circle in a sea of black. Even if you manage to find the sun, nudging a solar telescope back into position every few minutes to keep it in the field of view quickly gets irritating.

Cue the Sky-Watcher SolarQuest mount, a simple grab-and-go product that exists to solve exactly that problem. Costing around $585/£259-£359 (the latter with a tripod), it is not a general Go-To astronomy mount and it is not trying to be one. It is best understood as a dedicated solar tracking platform for small solar telescopes. That could range from regular telescopes wearing solar filters, most likely during a solar eclipse, to dedicated solar telescopes such as white-light-filtered refractors and H-alpha (Hydrogen-alpha) telescopes designed specifically for viewing the sun.

Sky-Watcher SolarQuest mount head: Design

• Lightweight and compact mount head
• Simple controls make it beginner-friendly
• Vixen-style saddle suits small solar scopes

The SolarQuest mount head weighs just 2.9 lbs/1.3 kg, accepts standard 45mm Sky-Watcher/Vixen-style dovetails and can be fitted to a tripod using a 3/8-inch screw. Meanwhile, the optional tripod is lightweight and easily adjustable, with a bubble level and accessory tray. Whatever tripod you use, it’s imperative to get it stable before using the SolarQuest because its ability to track the sun successfully depends on it.

With the optional aluminum tripod — which we used in our review — the total setup is still only around 9.9 lbs/4.05 kg, making it easy to set up inside and carry into the garden. Eclipse chasers travelling abroad will easily be able to store it in a carry-on camera bag.

The mount itself has very few controls: A power button and an 8-way sliding switch. A long press of the power button finds the sun, with the second used to make manual adjustments. There are no menus and no alignment tasks.

Sky-Watcher SolarQuest mount head: Performance

• Finds the sun automatically in clear conditions
• Fine-tuning controls keep the sun centered
• Works well with solar telescopes

At first glance, the promise of the Sky-Watcher SolarQuest mount head is so simple: you level the tripod using its built-in bubble or spirit level and point the attached telescope somewhere to the left of the sun. You then long-press the power button and step back. The built-in GPS calculates the date, time, and location, as well as the sun’s altitude and azimuth. The mount levels the telescope, pauses, then slews to the right altitude. Then its photodiode solar sensor (a small camera) hunts for the solar disc and locks on. In practice, the system gets impressively close to that ideal — but with some small caveats.

The sun needs to be in a clear sky, but it doesn’t have to be high. We reviewed the SolarQuest during a summer heatwave, when getting up very early was the only sensible way to observe the sun. Having got up early to take advantage of the cool morning air before the sun rose too high, we feared the SolarQuest would fail to find such a low sun. Luckily, there were no such issues, with SolarQuest taking just under 60 seconds to be perfectly aligned with the sun.

For visual observing, that’s transformative. Instead of spending the first part of a session aligning, shadow-aiming and nudging a scope into position, you can be looking at the sun within minutes. However, we did have to use the joypad on the SolarQuest to center the sun. Happily, the controls are very sensitive and move slowly, so we were able to have a perfect view of the sun in under two minutes from pressing the power-on button. That’s impressive.

Sky-Watcher SolarQuest mount head: Functionality

• Accurately tracks the sun
• 8x AA batteries are old-fashioned
• Payload is a limiting factor

Tracking accuracy is very good, with a tiny adjustment on the joypad required perhaps every few hours. Since it largely follows the sun’s path through the sky, it should be suitable for a total or deep partial solar eclipse, when a crescent sun could confuse the sensor (to be sure, you could cover the sensor during totality so it doesn’t hunt for the sun and try to realign during an eclipsed crescent sun).

However accurate it is, this is an alt-az mount. It can track the sun well but it cannot remove field rotation during much longer imaging sessions. For visual use and almost all solar use — including casual video capture — that is not a major issue. However, for long-duration solar imaging and creating time-lapses, it’s a limitation to keep in mind.

One practical complaint is the battery compartment. Pop open the door (which detaches and becomes easily lost) and inside is a small plastic cradle that takes eight AA batteries. As if needing to take a trip to a store before being able to use the SolarQuest wasn’t annoying enough, it occurred to me that if I was going to an eclipse, I would need to travel with at least eight more AA batteries as spares — and possibly another 16x for true peace of mind. Not a pleasant prospect. Should any gadget like this be AA battery-powered in the age of Lithium-ion and USB-C? A resounding no. The box includes a 12V DC connection but there’s no cable. It all seems poorly thought through and old-fashioned.

However, the main practical limitation of the SolarQuest is its 8.8 lbs (4 kg) payload, which sets it apart as an accessory for small solar telescopes. At its best when speed and simplicity matter, SolarQuest is a travel-friendly mount ideal for beginners and eclipse chasers seeking to remove a common frustration from solar observing — finding and tracking the sun — without adding complexity. It almost totally succeeds.

How we tested the Sky-Watcher SolarQuest mount head

We tried the SolarQuest for about two weeks with both a Celestron Regal M2 spotting scope (with a solar filter attached) for white-light observations of the solar disk and a Skywatcher HelioStar 76mm solar telescope. The latter was used to get some images of the sun in H-Alpha (Hα), in conjunction with a ZWO ASI174MM planetary camera.

Should I buy the Sky-Watcher SolarQuest mount head?

If you need something to support a solar or solar-filtered telescope under 8.8 lbs/4kg, the SolarQuest should be on your radar. It quickly finds the sun and tracks accurately, removing the need for manual alignment. It’s also really compact, operates quietly and has very simple controls.

The included instructions are poor, the way it’s battery-powered is far from ideal, and it’s limited by its payload capacity, but it’s so easy to use and quick to work that it’s hard to criticize the SolarQuest too harshly — it’s a slick and simple accessory.

If the Sky-Watcher SolarQuest mount head isn’t for you

There are very few dedicated solar trackers like the Sky-Watcher SolarQuest. However, some star trackers do have a mode where you can choose the sun as the star to track, including the Benro Polaris. Once you’ve entered the sun in the frame using the virtual joystick, the Polaris can automatically track it. Another alternative is an equatorial mount, which, when well aligned, can handle solar observing for longer periods and/or for making time-lapse sequences.

Solar observation can be tricky or underwhelming when trying to observe with handheld methods such as using solar eclipse glasses and solar binoculars. Hunting for the sun with binoculars can be tricky due to the essential ISO 12312-2 rated solar filters on the glass blocking all vision except for the solar disk itself. This is where a smart telescope like the entire Unistellar range can help; it automatically finds and tracks the solar disk from a few presses on your smartphone.

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All you need is to attach the correct Unistellar solar filter for your model, click Go-to on the Sun and the telescope will slew to the solar disk. If connected to a tablet or larger screen, you can get a much bigger image of the sun to share with groups and family. This also allows you to watch the observation from a shaded spot and get comfortable without needing to stay out under the beating sun.

Smart telescopes not only find and track the solar disk but they can image it too. Using built-in image focusing, stacking and processing, the telescope delivers a sharper image within seconds and reveals solar details like sunpots on the surface. If you don't want to miss getting a shot of the next solar eclipse, you can use the solar observation mode to capture the sun at all stages of the eclipse from your smart telescope. At the time of writing, the next total solar eclipse is coming on Aug. 12, 2026 and will be mainly visible in Greenland, western Iceland and northern Spain. Partial eclipses will be visible in some other European countries, parts of Canada and New York City.

What to do: A generalist step-by-step for most smart telescopes

• 1. Turn your smart telescope on
• 2. Link the smart telescope to a smartphone or tablet
• 3. Install the solar filter if the model requires a separate attachment
• 4. Select the sun on the app and wait for the location
• 5. Focus the image if needed and then use enhanced vision for more detail

What do you need?

For solar observation with a smart telescope, the first thing you will need is a smart telescope. While I'm going over how to use a Unistellar eVscope 2 for solar imaging and observation, most of the other smart telescope brands have models that are capable of this too, like the Dwarflab Dwarf Mini 3 and Vaonis Vespera II. If you are used to using a traditional telescope, bear in mind that you will need a smart device to operate the smart telescope and observe your targets. Most smart telescopes come with a tripod, so you shouldn't have to worry about getting one extra but it is an essential piece of equipment.

Next, you need a solar filter for your telescope. This is to protect the image sensors in the body of the telescope and drastically reduce the amount of light entering the aperture, so that you don't get a highly overexposed image. Many brands sell these solar filters separately and in the case of Unistellar, you have to make sure you get the right one for your model. There is a solar filter for their Odyssey range and then another filter for their pro range, which features the eQuinox 2 and eVscope 2 models.

Finally, you will also need access to somewhere with a good view of the sun, so a park, garden or open space is ideal. Solar imaging is best done in mid-to-late morning before the sun has heated up our atmosphere, which causes disturbance in the image. This is especially important if you are looking to get crisp shots of sunspots.

Observing and imaging the sun

Make sure your tripod is level, with your smart telescope properly attached, then turn it on and remove the dust cap. Open your preferred app and add your device by following the on-screen instructions.

Next, you should inspect your solar filter for any tears or holes, as any exposure to the sun without the filter can permanently damage the sensor. Installation is easy as you just clip the filter onto the end of your smart telescope.

After the device is connected, go to the list of sky targets in your app and it will allow you to browse or search for the sun. Click on it to bring up the go-to functions and if you are interested, more astronomical information about your chosen target.

Clicking on go-to for the sun brings up a series of slides to guide you through how to safely observe the sun with your device. The app also recommends positioning your telescope mount in the direction of the sun with the motor on your right to avoid any issues or delays in slewing.

After pressing go, the smart telescope should move and slew towards the sun. It can take a little while but it is rather exciting as you see the edges of the solar disk flash on the screen as the telescope gets closer and centers the image.

For smart telescopes with manual focusing, you will need to make sure that your image is in focus. Now on a bright sunny day, this can be tricky to see on a smart device screen but it is essential to getting a sharp image of sunspots. Using the wheel at the bottom of the eQuinox 2, I gradually adjusted the focus in small increments to allow for live image delay on my tablet. I used the sunspots as a guide for my focus, but it was still difficult because they don't become crystal clear during focusing, they just get slightly more defined and darker.

The real detail on the surface comes after you click enhanced vision mode or equivalent on the app, which starts live stacking of exposures of a few milliseconds and reveals a much more textured view of the solar surface. The sunspots get much sharper edges and you are able to see both the umbra and penumbra on some of them. In my imaging session, I got an image displaying the larger active regions of 4498, 4496 and 4492 as well as some smaller regions.

Observing an eclipse with your smart telescope

You should prepare well in advance if you are planning to observe a solar eclipse and test out the kit there before the big day. You don't want to be learning how to use your device on the day of the eclipse. Practice setting it up for solar observation a good few times before the day of the eclipse.

Using one of the best stargazing apps or the official Unistellar eclipse page, you can find out where the eclipse will be visible from and the time of maximum coverage in that location, so you can plan accordingly. The Aug. 12, 2026 total solar eclipse is just before sunset will be very low on the horizon, so you would need to find somewhere with a good view of the sunset and, ideally, do a practice run a week before. Setting up a few hours before the actual eclipse is necessary to avoid any last-minute disruptions and to get your telescope trained on the sun before the lunar disk starts to eclipse it. This is assuming that the skies are completely clear and free of clouds, but this is definitely something you should check before hauling your kit to a remote location. I use the Met Office Cloud cover map for the UK but other sites offer US and international coverage such as and Ventusky, SAT24 and Astrospheric.

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