ZWO ASI585MC Pro First Light

There’s a new camera in town, and it’s one of the most affordable cooled astronomy cameras ever made. The ZWO ASI585MC Pro may have a tiny sensor, but that doesn’t mean it can’t do what the big boys can. 

If you’re currently shooting with a DSLR camera – a dedicated astronomy camera may be on your wish list. The ZWO ASI533MC Pro used to hold down the ‘best starter astro cam’ category in my mind, so it will be interesting to see if the smaller 585 can live up to that title.

In this post, I’ll explain why you should consider the ZWO ASI585MC Pro and discuss the benefits and quirks of using a one-shot-color camera like this for astrophotography. I think this camera will be very popular in 2024, and I can’t wait to see the amazing results people get with it.

The ZWO ASI585MC Pro currently costs $599 USD at Agena Astro. 

Quick Overview:

The ZWO ASI585MC Pro is an affordable, cooled, dedicated astronomy camera capable of producing incredible deep-sky photos. It is also suitable for photographing planets, thanks to its high frame rate. The downsides of this camera are its small sensor size (which limits your field of view) and lower dynamic range than many higher-priced models. 

The ZWO ASI585MC Pro

Not to be confused with its uncooled planetary imaging camera counterpart, the ZWO ASI585MC Pro is a one-shot-color dedicated astronomy camera. Many people who start out using a DSLR camera for astrophotography move up to this type of camera to benefit from a cooled, astrophotography-modified sensor. 

The 8MP CMOS sensor in the ASI585MC Pro (SONY IMX585) was designed for long-exposure deep-sky astrophotography through a telescope. You can lower the temperature of the image sensor to below freezing to reduce noise in your images dramatically. 

While your DSLR has a bigger sensor and is easier to control and use with lenses, this little guy was built for taking 5-minute exposures, dual-narrowband filters, and live-stacking the Ring Nebula on your tablet. 

The ASI585MC Pro has an 8MP CMOS sensor with a 3840 x 2160 pixel resolution. 

Yes, there is a bit of a learning curve to switching to a dedicated astronomy camera – but when you get to the other side, you’ll wonder how you ever got by without a highly sensitive -10-degree CMOS sensor. 

Once you understand how to use a dedicated astronomy camera, everything from focusing your telescope to taking proper dark frames becomes easier. Unlike a DSLR or mirrorless camera, they were designed for long exposure deep-sky astrophotography.

Sensor Size

You might be wondering why the ZWO ASI585MC Pro is the cheapest option in this category. Well it’s the size of the sensor (and maybe the 12 Bit ADC). There are pros and cons of a sensor this small.

Pros: It’s great for photographing planets because that type of astrophotography requires a high frame rate. This unit can do almost 50 frames per second at its native resolution. A camera that is equally capable of planetary and deep-sky imaging is actually quite rare.

Cons: For deep-sky imaging, the field of view may be a little limited. Consider how much smaller your image frame is through a compact refractor telescope (430mm) compared to a DSLR.

The image frame is significantly smaller using the ZWO ASI585MC Pro compared to a crop-sensor DSLR.

You’ll need to work with and plan for it. The other key spec of this camera is the pixel size; at 2.9 microns, it is best used with a telescope in the 250mm—600mm range. 

The 12-bit thing seems to be the perfect argument starter on cloudy nights. Compared to the more expensive 14-bit ASI533, it’s possible that you could achieve a higher dynamic range with this camera’s older brother. 

From my experience, these specs don’t make as much of a difference in your actual images as you may think, but they are definitely something to keep in mind. A head-to-head comparison between the ZWO ASI533MC Pro and the ASI585MC Pro is in the works. 

ZWO ASI585MC Pro Specs:

• Sensor Type: CMOS 
• Sensor: 1/1.2″ Sony-IMX585
• Megapixels: 8.29MP 
• Resolution: 3840 x 2160
• Pixel Size: 2.9 microns
• Max Frame Rate: 46.9fps
• ADC: 12bit
• Working Temperature: -5℃ – 50℃
• Full Resolution Frame Rate: 47 FPS
• Full Well Capacity: 40Ke
• Peak Quantum Efficiency: 91%

Unlike some of the other ZWO cameras I have used (such as the ASI294MC Pro), this camera does not experience amp glow. While this can easily be calibrated using dark frames, it is nice not to have to deal with the issue whatsoever.

This camera also utilizes the SONY STARVIS 2 technology, which is said to provide a wider dynamic range and better signal-to-noise ratio. While it was originally designed to improve the quality of security cameras, it has benefits in astro-imaging applications as well. 

The back-illuminated sensor on the ZWO ASI585MC Pro improves the camera’s full well capacity (40ke). A larger full well capacity can collect light more efficiently and help prevent overexposing the brightest areas of your image. 

Thanks to a USB 3.0 interface with a built-in 512MB DDR3 cache, the ASI585MC Pro benefits from high-speed data transmission during your astrophotography sessions. The full-resolution images are only 12MB in size. 

The ASI585MC Pro includes an AR window (anti-reflection) but not a UV/IR cut filter. If you plan on capturing broadband targets such as galaxies, be sure to purchase a simple UV/IR cut filter (or light pollution filter). 

AstroBackyard Facebook user Francis Bossé captured this incredible image of the Squid Nebula using the ZWO ASI585MC Pro. 

My Deep-Sky Astrophotography Setup 

I used the ZWO ASI585MC Pro over two nights through two separate telescopes. To fully appreciate this camera, it is wise to pair it with an astrophotography telescope with specifications that are a good match for this sensor. 

For the first night, I used the Starfield GEAR 115 triplet APO, which has a native focal length of 805mm at F/7. However, with the 0.8X reducer in place, it brings this system down to a respectable 640mm at F/5.6.

I have been very happy with the GEAR 115 refractor over the last 12 months, and I highly recommend this model (and the comparable Astro-Tech branded variation) for anyone looking for a mid-range, high-end refractor. 

The Starfield GEAR 115 refractor on a ZWO AM5 strain wave mount. 

This telescope weighs 15 pounds, which is well within the maximum payload capacity of the ZWO AM5 without the need for a counterweight. With all of my camera accessories attached, the entire imaging system weighed approximately 20 pounds. 

I can’t say enough about the AM5 Strain Wave Mount. It has been a true workhorse for nearly 2 years straight and is a dream to control via the ASIAIR. If you are looking for a new telescope mount, be sure to read my best astrophotography mounts article covering some of the smartest choices in 2024.  

• Camera: ZWO ASI585MC Pro
• Filter: Optolong L-eXtreme (2″)
• Telescope: Starfield GEAR 115
• Reducer: Starfield 0.8X Reducer
• Mount: ZWO AM5
• Controller: ZWO ASIAIR Plus

As you can see in the photo above, I used a small 50mm guide scope and guide camera for autoguiding and dithering. The autoguiding is done using the multi-star guiding mode on the ZWO ASIAIR mobile app. 

Image Scale and Resolution

As a general rule of thumb, it is best to pair your camera with a telescope that will provide an image scale of 1.0 – 2.0 arc seconds per pixel for a well-sampled image with round, sharp stars. 

My image scale using the Starfield GEAR 115 was about 1 arc seconds per pixel (2.9 / 640 x 206). While I could get a slightly sharper image using something like the William Optics RedCat 61 at 300mm, I wanted a little more aperture to pull in those photons.

If you want to achieve a well-sampled image, stick to optical systems in the 250-500mm focal length range. This is a convenient option for anyone shooting with a wide-field refractor telescope like the ones listed below.

Good Matches for the ZWO ASIA585MC Pro pixel size and image scale:

 

• William Optics RedCat 61 (1.9 arc seconds/pixel)
• William Optics GT71 (1.4 arc seconds/pixel) 
• Askar FRA500 90mm (1.19 arc seconds/pixel) 

Which Gain Setting should be used with the ASI585MC Pro?

I almost always use a ‘medium’ gain setting (for certain cameras, it is called Unity Gain) for all of my ASI dedicated astronomy cameras. For example, on the ZWO ASI2400MC Pro one-shot-color camera, I use gain 158 for every single project I take on.

I have found the medium gain setting (usually in the 100-200 gain range) to be a great all-purpose gain value for a wide variety of astrophotography projects, including targets with a high dynamic range and extremely bright areas. 

Perhaps I have been a bit blind to potentially oversaturating the brightest stars or highlights in the field, but I use shorter exposures to compensate for this. However, I now realize that using the medium gain setting is not ideal for every camera and every project. 

For my test images with the ASI585MC Pro, I used the built-in HCG mode (high conversion gain), which automatically kicks in when you choose the medium gain setting of 252. However, some folks have recommended that I use a setting of gain 100 with the ASI585MC Pro.

Using a gain of 100 seems to be the sweet spot in terms of balancing read noise and full well capacity when capturing a broadband target with sub-exposures in the 120-second to 180-second range. 

Running an Imaging Plan

The ZWO ASIAIR Plus (I actually used the ‘Pro’ version for this project) makes it super easy to try out this camera’s live stacking features and then run my entire rig, including the mount, for an all-night project.

The target was an emission nebula in Cygnus known as Sharpless 112 – something that I’ve never shot before. I found this one by using one of the ‘HiPS survey‘ overlays on the Stellarium desktop software, which is really useful for planning nebula projects. 

The HiPS (hierarchical progressive survey) overlay in Stellarium. 

Sharpless 112 was the perfect size for my field of view using this system, and it was a great fit for the dual-narrowband Optolong L-eXtreme filter I had in front of the camera. 

The following night was clear, so I set up again with the huge Sky-Watcher Quattro 300P Newtonian Reflector. This time, I chose to capture the Crescent Nebula in Cygnus, and it looked incredible as each subframe came through.

My Image Results

I did want to highlight that I saw a few weird frames throughout each session, and I am still unsure of the cause. It was apparent in my imaging plan thumbnails on the ASIAIR (see the image below) and even more visible when I blinked the subframes using PixInsight.

Frames 28 and 29 show a ‘brightening event’ with some odd artifacts. Thankfully, the anomaly corrected itself over time, and the following image frames did not have these issues. 

Examples of the strange artifacts appearing in my subframes during an imaging session. 

I can confirm that these are not clouds, so I don’t know if its the sensor adjusting to the ambient temperature or what. I’m sure there is an explanation; I just don’t know what it is.

I still managed to get a great image of the crescent, but I thought it was important to highlight that anomaly. If you have the ZWO ASI585MC Pro, let me know if you’ve seen anything like this in the comments. 

Sharpless 112 in Cygnus. 60 x 3-minutes using the ZWO ASI585MC Pro. 

The Crescent Nebula. 37 x 3-minutes using the ASI585MC Pro and Sky-Watcher Quattro 300P.

Please keep in mind that these are just ‘first light’ test images without the adequate amount of time and proper calibration to truly show the potential of this camera. I will continue to use the ZWO ASI585MC Pro in the coming months to produce even better images. 

Results from Others using the ZWO ASI585MC Pro

The AstroBackyard Facebook page is a great place to see countless images of deep-space objects captured by others. I asked the owners of the ZWO ASI585MC Pro to share their image results, and I was blown away by the images they shared. 

ASI585MC Pro VS ASI533MC Pro

The ZWO ASI533MC Pro has long been a favorite dedicated astronomy camera for beginners. Compared to the ASI585MC Pro, it has a higher dynamic range, a larger pixel size, and a slightly larger full well capacity.

While I believe the ASI533MC Pro is worth the added cost (it’s a fantastic astronomy camera overall), it is interesting to compare the subtle differences between these cameras’ specifications:

Specification	ZWO ASI585MC Pro	ZWO ASI533MC Pro
Sensor	Sony IMX585 CMOS	Sony IMX533 CMOS
Sensor Size	1/1.2"	1"
Resolution	8.29 MP (3840 x 2160)	9 MP (3008 x 3008)
Pixel Size	2.9 µm	3.76 µm
Full Well Capacity	47,000 e-	50,000 e-
Quantum Efficiency (Peak)	91%	80%
Read Noise	0.9e @ high gain mode	1.0e @ high gain mode
Memory Buffer	512 MB DDR3	256 MB DDR3
Frame Rate (at Full Resolution)	46.9 FPS in 12-bit mode	20 FPS
Dynamic Range	11 stops	14 stops
Price	Lower compared to ASI533MC Pro	Higher compared to ASI585MC Pro
Applications	Deep sky, planetary, lunar imaging	Deep sky, planetary, lunar imaging

Final Thoughts

Two things about the ASI585MC Pro stand out to me. One is that it would make a perfect live-stacking camera for outreach and fun in the backyard. 

I’ve been using the ASI533MC Pro for this purpose, but I think this will work even better because I can throw on a Barlow lens and hop over to a planet with a high frame rate. 

The other thing is the 4K image resolution. This is perfect for a YouTube reveal image. I know that’s not something most people will think of, but the square sensor on the ASI533 made it awkward for me to display my final image in a long-format video.

Another benefit that I should have mentioned in the video is that the stacking process of the image frames captured with this camera is faster than those of larger sensor models. In terms of file size, each subframe is just 12MB in size (compared to almost 50MB in an APS-C-sized sensor).

This helps speed up the calibration and stacking process using your favorite image-stacking software. While I still have plenty of testing to do, I think the ASI585MC Pro has the potential to be a pivotal product in the astrophotography community. 

For many DSLR owners, this will be their first experience with a cooled astronomy camera. Thankfully, there are plenty of great resources to help them through this crucial next step of their journey. 

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Trevor Jones is a deep-sky astrophotographer and a valued member of the RASC. His passion is to inspire others to start their astrophotography journey on his YouTube Channel, so they can appreciate the night sky as much as he does. His images have been featured in astronomy books and online publications, including the NASA Astronomy Picture of the Day (APOD).

Related Posts: 

• • • ZWO ASI533MC Pro (First Look)
    • CCD vs. DSLR – A New Learning Curve
    • When to Start Using a Mono Astrophotography Camera