ZWO’s original non-cooled mono and colour versions of the ASI585, aimed at planetary imagers, were very well received for their fast frame rates and extremely low noise.
So when ZWO announced it was adding the very same Sony STARVIS IMX585 sensor to its deep-sky camera range, complete with two-stage cooling systems, we couldn’t wait to get our hands on one to try it.
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This ‘active cooling’ ability allows you to set the temperature of the sensor to as low as 35° below ambient and further reduce noise in what was already a proven low-noise sensor.
Unboxing the ZWO ASI585MM Pro
Opening the box, we found the ZWO ASI585MM Pro, with familiar bright-red camera body, nestled in
a padded zip-up compact case.
Included with the camera were three USB cables and a range of adaptors and spacers – a nice touch from ZWO that will help users avoid having to buy extras (often an unforeseen additional expense).
Making the most of these, we easily attached our non-ZWO filter wheel and correctly spaced our field flattener.
As with all ZWO’s Pro series cameras that feature two-stage cooling, we did note that no power cable was included.
You’ll therefore need a suitable 12V 2.1mm power supply for the ZWO ASI585MM Pro.
After a quick look on the ZWO website, we located the Downloads section and were pleased to see a single driver file covering all their cameras, meaning we didn’t need to hunt for the correct one.
Adding our own power supply and the supplied USB 3.0 cable, we got the camera connected and it was instantly recognised by our capture software.
Utilising the USB hub on the back of the camera, we connected the filter wheel and motorised focuser, both of which were discovered by our PC instantly and worked flawlessly, proving this to be a great addition.
With everything now connected, we started the camera cooling.
ZWO ASI585MM Pro and signal vs noise
Once the ZWO ASI585MM Pro was holding its temperature, we set up to capture some dark frames ranging from 30 seconds to 15 minutes in length, to check how the camera handled noise and other artefacts.
Each resulting calibration image was very clean, and we noted that noise was well controlled throughout.
The late spring nights meant that true astronomical darkness was on its way out, but we soon had a clear
night to test the ASI585MM.
We waited until the Sun had set and Cygnus was rising.
Slewing over to the Propeller Nebula, DWB 111, and with a default medium Gain setting selected, we were pleased to see a bright star field even at very short exposures.
With no true darkness available to us, we capped the exposure length at 30 seconds to try to limit the effect of the lighter skies and a reasonably bright waning Moon.
Starting with our Ha filter selected, we spent the next couple of hours capturing some hydrogen-alpha data, before reaching for the OIII filter once the Moon had passed.
With our first batch of data collected, we proceeded to get it stacked and processed.
Having only captured around 60 minutes on each filter, the Ha data appeared clean.
However, once we stretched it in our processing software, it became apparent that more data was needed as fainter areas were grainy and patchy.
This was confirmed when a few nights later we processed 150 minutes of Ha data on the Elephant’s Trunk Nebula, IC 1396, in Cepheus, which was far cleaner and handled a more extensive stretch.
ZWO ASI585MM Pro in a nutshell
All in all, the ZWO ASI585MM Pro was a great camera to use and ZWO has once again ensured
an incredibly easy setup.
For first-time mono users, it’s a step up in terms of capture time and processing skill from a basic one-shot colour (OSC) camera.
The ASI585MM Pro may be ZWO’s lowest-cost active cooled mono camera, but the results returned are anything but budget.
ZWO ASI585MM's mono sensor
The ZWO ASI585MM Pro is fitted with a mono version of Sony’s popular IMX585 sensor.
This 1/1.2-inch (11.2mm x 6.3mm) CMOS sensor has 2.9μm pixels and a resolution of 3,840 x 2,160, promising low image noise and zero amp glow.
The IMX585 is part of Sony’s backlit STARVIS 2 range, suggesting increased light sensitivity and a high signal-to-noise ratio for the camera’s price point.
Throughout testing, we indeed observed no amp glow in our images, even when pushing exposures up to 15 minutes with the default Gain setting set to high and a cooler temperature of –10°.
Examining each frame also revealed relatively low noise.
Another strength of the ASI585MM Pro is its ability to capture frames at high speed, ensuring it can double as a planetary camera.
ZWO advertises a frame-capture speed at full resolution of 47 frames per second, which we achieved with ease during our review.
Dropping the capture area to 500 x 500 pixels, we were achieving frame rates exceeding 150 per second, making this a very versatile dual-purpose camera.
ZWO ASI585MM best features
Extension tubes and adaptors
Included with the camera body is an impressive selection of extensions and adaptors that will allow you to connect the ASI585MM to almost any accessory. In the box is an M42 to M48 adaptor, 16.5mm M42 to M48 extension, 21mm M42 extender, M42 to 1.25-inch adaptor, spacers and a 1.25-inch nosepiece.
USB hub
ZWO has included a USB 2.0 hub on the back of the camera, which consists of two USB 2.0 ports that are supplied by the same USB 3.0 cable that controls the camera. This allows for the connection of additional accessories such as filter wheels, guide cameras or focus controllers, reducing cable clutter.
Active cooling
Because the ASI585MM has two-stage cooling, you can achieve a temperature of up to 35ºC below ambient with this camera. During use, we easily achieved and maintained –10ºC during exposures, while the outside temperature was around 20ºC. SGPro reported the cooler systems were only using 54% power.
Carry case
The camera is supplied in a well-padded and very sturdy bag, designed in ZWO’s characteristic black and red colour scheme. This carry case securely zips up and ensures the camera can be stored securely and safely, free from moisture and dust when it’s not in use.
USB cables
ZWO doesn’t scrimp when it comes to accessories, providing three USB cables. The first is a red USB 3.0 cable which controls the camera; at two metres long, it will meet most needs. The second and third are shorter, 0.5-metre right-angle USB 2.0 cables to allow you to connect additional accessories.
ZWO ASI585MM key specs
- Price: £699
- Sensor: 4K Sony IMX585 CMOS
- Resolution: 3,840 x 2,160
- Exposure range: 32ms–2,000 seconds
- Connectivity: USB 3.0
- Size: 73.5mm x 78mm
- Weight: 453g
- Supplier: First Light Optics
- Email: questions@firstlightoptics.com
- www.firstlightoptics.com
This review appeared in the August 2025 issue of BBC Sky at Night Magazine
