ZWO ASI585MM Pro review by Cuiv

The ZWO ASI585MM Pro is a compact, cooled monochrome astrophotography camera that brings professional-level performance to a broader audience. As ZWO’s most affordable cooled mono camera, it’s designed to be both beginner-friendly and powerful enough for advanced users looking to capture high-resolution deep sky and planetary images.

At its core is the Sony IMX585 monochrome sensor, a back-illuminated CMOS chip with 2.9-micron pixels and a resolution of 3840 x 2160 (8.29MP). This sensor format (1/1.2") is well-suited for capturing fine details, particularly when paired with short to mid-range focal length telescopes. It also features an impressive peak quantum efficiency of 91%, making it highly sensitive across the visible and near-infrared spectrum.

ZWO ASI585MM Pro review & thoughts

One of the camera’s standout features is its two-stage thermoelectric cooling system, capable of reducing the sensor temperature by over 35°C below ambient. This cooling dramatically cuts down thermal noise during long exposures, allowing for much cleaner images even in warmer environments. Combined with its zero amp glow circuitry, users get exceptionally clean dark frames, no matter the gain or exposure length.

Cuiv, The Lazy Geek, has just dropped a full review of the ZWO ASI585MM Pro Monochrome camera. You can check out his other videos on his YouTube channel, but below, we’re sharing our own take of the 585MM —with Cuiv’s commentary sprinkled throughout.

The ASI585MM Pro supports high-speed readout via USB 3.0, achieving up to 47 frames per second at full resolution in high-speed mode. It includes 512MB of DDR3 buffer memory to ensure stable data transfer, especially helpful during planetary imaging or when stacking large volumes of subframes. The camera also includes a USB 2.0 hub for powering accessories like filter wheels and focusers directly from the camera body.

With a full well capacity of 47,000 electrons, dynamic range up to 12.5 stops, and read noise as low as 0.7e in high conversion gain mode, the ASI585MM Pro performs well across a wide range of imaging conditions. Whether under dark skies or in light-polluted urban areas, it gives users the flexibility to fine-tune gain settings for optimal results.

Physically, the camera follows ZWO’s familiar red anodized aluminum design and includes essential accessories for achieving the standard 55mm backfocus. It’s powered by a 12V DC input (3A recommended), and integrates perfectly with ZWO’s ASIAIR ecosystem. Altogether, the ASI585MM Pro is a well-rounded, budget-friendly entry into the world of monochrome astrophotography.

ASI585MM Pro specifications

• Sensor: Sony IMX585 CMOS​
• Sensor Format: 1/1.2"​
• Resolution: 3840 x 2160 pixels (8.29 megapixels)​
• Pixel Size: 2.9µm​
• Diagonal Size: 12.84mm​
• Shutter Type: Rolling shutter​
• Exposure Range: 32µs to 2000s
• Readout Noise: Ranges from 0.8e to 12e (e.g., 2.4e at 15dB gain)​
• Quantum Efficiency (QE) Peak: 91%​
• Full Well Capacity: 47,000 electrons
• Analog-to-Digital Converter (ADC): 12-bit​
• USB Interface: USB 3.0 for high-speed data transfer​
• Adapters Included: 2”/M42X0.75​
• Protective Window: AR-coated D32*2mm
• Camera Dimensions: Diameter of 62mm
• Weight: Approximately 126g
• Back Focus Distance: 6.5mm or 17.5mm​
• Operating Temperature Range: -5°C to 50°C​
• Operating Humidity Range: 20% to 80% relative humidity​
• Supported Operating Systems: Windows, Linux, and Mac OSX​
• Maximum Frame Rate: Up to 46.9 frames per second at full resolution​
• Cooling System: Two-stage TEC cooling capable of reducing sensor temperature to more than 35°C below ambient​
• DDR Buffer: 512MB DDR3 memory for stable data transmission​
• USB Hub: Integrated USB 2.0 hub for connecting accessories like electronic filter wheels or focusers
   

This camera supports USB 3.0 connectivity, and includes a built-in USB 2.0 hub at the back for easy connection of a filter wheel and electronic focuser. A 12V 3A power input is required for the camera to operate, and as expected with ZWO, a power supply is not included. However, it comes with everything else needed to get started, including multiple adapter rings for achieving the common 55mm back focus distance, a C-mount adapter, and fine spacers to tweak the orientation and spacing of accessories.

ZWO doesn’t currently offer a bundled filter wheel or filter set with the ASI585MM Pro, which is something to consider when comparing this camera to others on the market. For instance, the QHY Minicam 8 Mono and Topteek ATR585M include complete filter bundles for around $800 to $900. Despite this, ZWO's ecosystem, especially the ASIAIR platform, makes this camera very appealing for beginners who want an integrated and easy-to-use system.

Functionally, the ASI585MM Pro is nearly identical to its color sibling, the ASI585MC Pro. They share the same sensor performance and behavior, including gain settings, high conversion gain thresholds, and read noise profiles. The major difference is the absence of a Bayer matrix in the monochrome version, allowing it to capture unfiltered light directly and provide higher resolution and detail per pixel. This makes the camera ideal for combining red, green, and blue filtered exposures into full-color images. When used skillfully, the result is a dramatic improvement in image quality over one-shot color imaging.

The pixel size of 2.9 microns gives the ASI585MM Pro an edge in resolution over popular sensors like the IMX533 or IMX571, which have 3.76 micron pixels. While this does result in a smaller sensor area, the high pixel density means more detail can be extracted from small objects like galaxies and planetary nebulae when paired with fast optics or longer focal lengths. Field of view analysis using common telescopes showed that with a fast 800mm Newtonian or a small wide-field refractor like the RedCat 51 or SQ55, the sensor performs well across a variety of target types, from galaxies like M101 to the sprawling Andromeda Galaxy.

ZWO's cheapest cooled monochrome camera

In testing, the ASI585MM Pro delivered impressive results. A luminance-only image of the EUO Galaxy captured from Tokyo using a 150mm f/3.8 Newtonian telescope demonstrated excellent contrast and detail. Despite the city's light pollution and limited data, only two hours of 60-second exposures, the resulting image showed the potential of the camera even in suboptimal conditions. Processing the image using tools like BlurXTerminator and NoiseXTerminator further improved the clarity, revealing a sharp and detailed galaxy core.

Quantum efficiency is another standout aspect of this camera. With peak values reaching 91% and remaining above 75% across much of the visible spectrum, the IMX585 sensor used here outperforms many well-known monochrome sensors in ZWO's own lineup, including the IMX533 and IMX571. This is especially important for narrowband imaging, where high efficiency at specific wavelengths like H-alpha, OIII, and SII can make a substantial difference. The IMX585's sensitivity in these regions is excellent, hitting above 80% for H-alpha and above 90% for OIII, making it an exceptional choice for nebula imaging.

One area where the camera invites some discussion is its 12-bit ADC. While some may see this as a limitation compared to 14-bit cameras, the real-world performance suggests otherwise. Dynamic range, what truly matters in practical imaging, is solid. The camera reaches a maximum of 12.5 stops of dynamic range at low gain settings and maintains good performance even as gain is increased. The transition point from low to high conversion gain is around gain 252, a setting that drastically reduces read noise and boosts dynamic range thanks to the sensor's internal amplification switch. While the reviewer suggested that this transition could have occurred at a slightly lower gain value for optimal flexibility, it still provides a meaningful advantage in real-world usage.

Gain selection is an important factor when using this camera effectively. For broadband imaging in light-polluted areas, low gain (e.g., gain 0) is ideal, as read noise is overshadowed by light pollution anyway. For narrowband work or imaging from darker locations, using high gain (252 or higher) to access the high conversion gain mode is recommended to minimize read noise and maximize image quality. For mid-range conditions, like suburban skies, intermediate gain settings around 125 provide a reasonable compromise between noise, dynamic range, and detail.

ASI585MM/CC Pro Dark current vs temperature

Cuiv's review of the ZWO Cooled Monochrome camera

In terms of real-world measurements, SharpCap analysis confirmed ZWO’s published specs. The user tested various gain settings and found that read noise, full well depth, and dynamic range aligned closely with theoretical expectations. The sensor’s behavior was consistent and predictable, giving users confidence in planning their imaging sessions.

One clever use case the reviewer highlighted was the combination of data from the monochrome ASI585MM Pro with images from its color counterpart, the ASI585MC Pro. By using the monochrome camera for high-detail luminance data and the color camera for RGB, it's possible to achieve results comparable to full-filter setups, without needing a filter wheel at all. This approach makes the ASI585MM Pro a powerful addition to multi-rig imaging setups or for users who already own the color version of the camera.

Ultimately, the ASI585MM Pro is a strong offering in ZWO’s product line. It bridges a gap in the market by delivering high-end monochrome imaging performance in a small-sensor, low-cost package. While its small sensor size may be a limitation for some wide-field targets, that issue can be overcome with the right choice of optics. Its compact form factor, compatibility with ZWO accessories, and reliable cooling system make it ideal for portable setups and lightweight rigs.

The camera's real strength lies in its flexibility. With high quantum efficiency, fast readout, and excellent performance across a range of gain settings and conditions, it provides a capable platform for deep sky imaging, particularly in narrowband. For those interested in starting monochrome imaging or looking for a compact second rig, the ASI585MM Pro presents a compelling option. The low price point, consistent with ZWO’s strategy of lowering the barrier to entry, only strengthens its appeal.

For astrophotographers who value image detail, who want to explore the benefits of mono imaging, or who already use ZWO's ASIAIR ecosystem, the ASI585MM Pro is well worth considering. With proper filters and thoughtful planning, this small sensor camera can deliver results that rival much more expensive systems, proving once again that size and price aren’t always the best measures of astrophotography potential.

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Buy the ASI585MC/MM Pro