Getting Started With The ZWO ASI Air Plus
The ASI Air Plus is a standalone imaging controller that runs Linux-based ASIAir software. It connects to your mount, camera, focuser, and filter wheel via USB, then handles plate solving, autoguiding, and sequencing without needing a laptop. You control it through a web interface or the mobile app once it is connected to your local WiFi network. I spent three seasons trying to make it work reliably before settling into a routine that actually stuck. The manual is basically the official PDF that ZWO released when the device shipped, and it covers everything from initial setup to advanced scripting. It is not particularly well-written, but it is the primary reference document.
Where To Find The Zwo Asiair Plus Manual
The manual is available for free on ZWO's website under the ASI Air Plus product page. There is also a quick-start guide separate from the full document. I recommend downloading both, though the quick-start skips a lot of the troubleshooting details that end up mattering most once you hit real sky conditions. You can also find community-maintained documentation on Cloudy Nights and the ZWO forum. Those threads tend to have more current information than the official PDF since the software updates regularly and the manual often lags behind.
Setup Steps That Actually Work
First, power the unit on and connect it to your telescope setup. The ASI Air Plus has four USB ports and two dedicated guider ports. Camera goes into the USB 2.0 port, mount into USB 3.0, and if you have an auto-focuser like the EAF, that gets its own port. The guider camera connects to one of the small connectors on the side. Next, power everything up. The ASI Air Plus draws power from the same source as your mount, so a single battery plugged into the mount's power output is usually sufficient for a basic setup. If you are running a heavy filter wheel plus a cooled camera plus a mount, you may want a dedicated power supply for the ASI Air itself. The WiFi network is named something like ASI_Air_Plus_XXXX. Connect your phone or laptop to it, then open a browser and navigate to 192.168.6.1. That brings up the web interface. From there you can create an account, register your equipment, and start building imaging sequences.
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Common Problems And What I Found Actually Helps
Plate solving fails more often than you would expect, especially on the first target after sync. The ASI Air tries to solve using the built-in solver first, and if that times out it falls back to astrometry.net. The fallback is slower and sometimes does not trigger at all depending on your firmware version. My workaround was to disable the built-in solver entirely in the settings and force all plate solving through astrometry.net. This adds roughly 30 to 45 seconds per solve attempt, but the success rate jumped from maybe 60 percent to nearly 100 percent. The trade-off is patience on cold starts when the plate solving queue backs up. Another issue: the ASI Air Plus loses its WiFi connection randomly during long sessions. This happens most often after 3 or 4 hours of imaging. The fix is straightforward but annoying. You go into the network settings and enable the option to reconnect automatically. It does not always work cleanly, so I keep a small USB Ethernet adapter handy. When the WiFi drops mid-session, a quick wired connection lets me check on things without losing the mount's GoTo coordinates.
I also ran into a problem where the filter wheel positions drifted after a cold soak below freezing. The EAF compensation kicked in but the filter wheel was still misaligned by one position. I had to manually re-zero the wheel in the web interface and then re-run the focus calibration. ZWO acknowledged this in a forum post six months after it became a common complaint. The workaround they suggested was to let the wheel warm up to ambient temperature before starting the sequence rather than running it cold from the beginning.
What Beginners Miss
The ASI Air Plus does not support every camera natively. ZWO lists a compatibility table, but cameras outside that list sometimes work if you use the generic CMOS mode. I had a colleague try an older QHY camera that was not on the list, and it worked fine for light frames but refused to guide. The guiding camera handled that part instead, which meant splitting responsibilities between two devices rather than keeping everything in one chain. Autoguiding through the ASI Air Plus is functional but not as refined as dedicated guiding software like PHD2. The guiding algorithms are simpler, and you do not get the same level of control over dither patterns or guiding parameters. For short sub-exposures up to about 60 seconds on a well-balanced mount, it is adequate. Beyond that, I recommend running a separate guide camera connected to a laptop with PHD2. There is also a limit on sequence complexity. The built-in sequencer handles basic multi-sub sequences, Darks, Flats, and Bias frames fine. But if you want to do something like a variable exposure sequence with different filter exposures per target, you will hit the ceiling quickly. The scripting language supports some customization, but it requires reading the manual carefully and testing each script individually.
The Honest Downsides
The hardware is limited by design. The processor inside the ASI Air Plus is not powerful enough for heavy real-time image processing. Stacking and calibration happen on the device itself for basic tasks, but if you try to process larger files the system slows down noticeably. Some users report the unit becomes unresponsive after a sequence with more than 50 frames, requiring a restart. Another limitation: the ASI Air Plus does not natively support ASCOM. If your workflow depends on third-party ASCOM drivers for specialty equipment, you are out of luck unless those manufacturers provide native ASIAir support. This excludes a significant portion of niche imaging gear available on the market. The WiFi range is also a real constraint. Once you move more than 30 feet from the unit, the connection becomes unstable. I learned this the hard way when I set up in my backyard and tried to monitor the session from inside the house. The connection dropped every few minutes, and I lost two frames of guidance data before realizing what was happening. A simple WiFi extender solved that problem, but it adds cost and another potential point of failure.
If your setup involves multiple telescopes or frequent reconfiguration, the ASI Air Plus becomes cumbersome. Each telescope requires its own star catalog and plate-solving calibration. Switching between setups means rebuilding sequences from scratch rather than saving and loading profiles the way a laptop-based solution would allow. In that scenario, a dedicated imaging computer or even a Raspberry Pi running PixInsight or N.I.N.A. would be more practical.
Bottom Line
The ASI Air Plus works well for a single telescope setup with standard equipment, particularly if you value simplicity and want to eliminate the laptop from your imaging workflow. It is not a universal solution. The plate-solving fallback, the WiFi instability, the ASCOM limitation, and the processing ceiling are all real constraints that show up during actual use. If you can work around those, it saves you a lot of hassle on location. If you cannot, it is better to know before you invest the time setting it all up.
