Spin me right around baby! The ZWO CAA has been out for a couple of months now, and I was able to get my hands on one for review. I did have to ask ZWO directly, and they politely obliged.
I’ve seen this product requested a lot online, and on the ZWO Facebook pages as well. It’s been in development for a while now and I did share my ZWO CAA initial impressions when I saw it announced.
I’ve never used a rotator before, and there have been instances where I felt it would be beneficial. I initially thought the price was a bit high, but I’ll talk about that a bit later in the review.
So then, let’s begin with the ZWO Camera Angle Adjuster review.
Contents
- Why Use The ZWO CAA?
- Rotation And Flat Frames
- ZWO CAA Build Quality
- Carry Capacity
- Using The ZWO CAA
- Cable Snagging
- Meridian Flipping
- Issues With The ZWO CAA
- Pricing & Conclusions
- Video Review
Why Use The ZWO CAA?
The first question is, naturally, why would you even want a rotator like the ZWO CAA? The most obvious is so you don’t have to keep loosening the camera. If you use a standard connector where you tighten your camera assembly into the focus tube with the compression rings, the standard practice is to loosen it and then rotate it before starting a project.
If your telescope has screwed on connections, and it doesn’t have a built in rotator within the body of the focus tube on the telescope. Then you’re limited to where the camera sits after tightening it up. In this instance, a rotator will definitely be useful.
However, the biggest problem I found and therefore the biggest advantage of the ZWO Camera Angle Adjuster is when you’re making a night’s imaging plan. It is extremely common for something to get in the way of your imaging session – a house, a light, a tree. In this case, all you can do is to change target. But changing target also has problems – unless your second target has the same rotation as your first target, you’ll have issues.
Before a camera angle adjuster, you’d have to possibly wake up early, go out, take some flats, then rotate your assembly before starting the new target. On top of that, every time you wanted to go back to the first target, you’d again have to rotate and try your best to match the rotation.
So when making plans, you can program in a new rotation whenever you change target during a night imaging. That way, you can get the maximum amount of light gathered during clear nights. Especially in countries like the United Kingdom, where we don’t get many clear nights anyway.
Rotation And Flat Frames With The ZWO CAA
The ZWO CAA has a rotational accuracy of 0.02′ of rotation. So, extremely accurate. This means that you can always match your rotation you’ve been using for your imaging session. So, make your plan, have multiple rotations, and you can always recreate them – assuming you haven’t unplugged and unscrewed anything.
This also means it’s helpful when it comes to shooting your flat frames. When you rotate the camera, you’ll be making a change to the imaging train. This is a massive no-no when it comes to flat frames though. If there’s dust in one part of the image and you rotate, then it will move when you rotate. Which means any previous flat frames aren’t suitable.
If you can match the rotation, it means you can always match again when taking your flat frames. Since the ZWO CAA is so accurate in its rotation, it’s easy to program. Extremely beneficial for multi-target imagers, a huge benefit for every clear night and allows for greater consistency in the imaging.
ZWO CAA Build Quality
I find that ZWO products are of a good build quality, and I’m happy to say the ZWO CAA is no different. When you open the box, you will see it packed snug and securely in its formed foam and presented really well.
The red anodised metal finish also has a slightly textured look to it. However it is still smooth. Some of the labels are transfers though and not etched in or permanently engraved on.
The weight feels nice and sturdy and the threads are engineered nicely with good peaks on them. It doesn’t look like it’s made of cheap materials and has a good machined quality to it.
The ZWO CAA has M54 x 0.75 threads on the telescope side, which pairs perfectly with ZWO telescopes as would make sense. However, for me and my Sky-Watcher Evostar and its M56 threads, I had to source adaptors.
One issue I did encounter here was when I threaded my M56 to M54 adaptor on the threads are actually a little too tight. It became really hard to screw it down nicely. This would be a combination of the threads on both the adaptor and the ZWO CAA. So I would certainly say maybe a very light thin grease would help. Only a tiny bit needed, just to lubricate those threads and make it easier to undo.
The rotation side comes pre-installed with the M54 plate also. Remember, it’s a ZWO product so it’s been designed to work straight out the box with other ZWO Products. However it does also come with an M48 plate. Included also in the box is the allen key needed to change the plate over and to use the locking hole, the USB cable and a colour quick reference guide.
So, top marks for build quality here.
ZWO CAA Carry Capacity
Next up then: how much can this thing actually carry? As already discussed, it has good quality threads on it so it can screw down nicely. But the motors in it still have to shift the camera assembly with any accessories used.
ZWO’s marketing say it can handle 4.4kg or so, which is abut 9lbs 11oz. So… I want to test that. I have a DSLR camera which is about 750 grams, so I needed to add some weight to this. I wasn’t going to test it to failure as it’s a review sample. But I chose to add 4 bags of rice to this camera.
In adding 4kg of weight to the DSLR I had attached, it was more tricky to get the rice to stay in place. However, during the actual use the ZWO CAA was able to rotate quickly, quietly and smoothly even with the additional weight hanging on to it. It barely noticed the additional weight.
Using The ZWO CAA
I did struggle a bit. At first, it didn’t actually rotate. The ASIAir app said it was connected and it said it was rotating, but the thing wasn’t actually moving. I tried giving it a shove here and there also but that didn’t help. In reality, I think I had actually tightened it up too much when I attached the camera. Backing it off and then nipping it back up sorted the issue and it began to rotate.
It rotates really, really – and I mean really – smoothly. It’s quiet enough, and accurate enough as well as quick enough to be practical. As mentioned earlier, it’s really straight forwards to program in certain angles and the CAA will match that angle really quickly.
You can manually control its rotation in the CAA tab of the ASIAir app, and also it has ASCOM drivers as standard so you can use external softwares like NINA to control it.
Once I had sorted out the rotating, it was time to make a plan. On the only clear night I had during testing. As I mentioned earlier here’s where I think it really comes into its own. I could take some images of say the Andromeda Galaxy, and then change over to the Pleiades, and then easily change the rotation.
On something like the ASIAir, select Plan mode. Then open the SkyAtlas (or just make some targets on the plan screen). Then, in the top right of the screen you see the rotation icon. Click that, and you can then program in your new rotation. It then saves it, and now the plan has that specific rotation planned as well. The mount will slew over to the new target, perform camera rotation, and then plate solve (if enabled).
Cable Snagging
One thing I was very eager to test was if the ZWO CAA would snag cables. Of course, we have to put our cables over the rotator and onto the camera. When the rotator spins, it will pull any slack out of the cables. So… will this cause problems? I don’t have particularly neat cable management at the best of times, but some slack is necessary of course. Moreso when you’re using a rotator.
I was curious as to if the camera will continue to rotate in one direction, for example clockwise. If it continued to do that all the while, it will inevitably and eventually take up all the slack in your wire and will begin to pull it. This could not only pull the cable out – which is a disaster anyway. But worse so it could cause damage to USB ports or cables. So I was keen to try this.
I made this atrocious plan. I took one image of M45, told it to rotate clockwise a bit, shoot another image of M45, rotate again in clockwise direction, shoot again etc. I had it repeat this until I had almost completed an entire rotation. I then sat back, hit the “begin plan” button, and observed. I was confident that ZWO engineers would’ve anticipated this. But you never can rely on these things until you test them yourself.
Thankfully, once it reached a certain rotation in one direction, it reversed itself and rotated in the other direction to reach the new orientation. I think it sets limits at the 0° and 180° angles where it will then go the other way around.
So… No. The ZWO CAA didn’t keep rotating in the same direction until it damaged wires or pulled cables. Which was refreshing to see. But that brings us onto a different part of an imaging night.
Meridian Flipping With The ZWO ZAA
One thing I noticed and have seen other people mentioning also is the meridian flip. As it will now platesolve to exactly match the framing you programmed, its being found that after a meridian flip, the CAA rotates the camera 180°. This would cause you to need new flat frames for example where before it wouldn’t cause a problem.
This means you may be forced to shoot new flat frames for the same imaging run on the same target. As of course if we’ve rotated the camera, we’ve rotated any artefacts on the imaging train around. It shouldn’t be a problem, but it depends on how the stacking algorithm works. In short, I would rather not see it rotate around after a meridian flip.
Though the firmware is new, and I’m sure ZWO are working on this to stop it from happening.
Issues With The ZWO CAA
No product is perfect. That’s my mantra. Every time I review something, I find something. In this case, the biggest issue I had after I figured out how to attach it was…. “Where am I going to put my filters?”.
With the adaptors I needed to use, I had nowhere to put my 2” filters. If I was using a DSLR then my only option could really be a clip in filter. I could also potentially fit a filter draw or filter wheel in front of the reducer, but that’s not necessarily best practice.
The ZWO CAA seems more designed and suited to have an imaging train that goes something like:
Telescope > CAA > Reducer > Spacers > Filter Wheel > Dedicated Imaging Camera
Another potential problem I’m spotting is actually focusing distance. It’s not so much back focus more so front focus. On my Sky-Watcher Evostar 80ED telescope for example, using the ZWO 585mc and my reducer, here’s the last distance it focused at. I have only about 26mm forwards travel remaining. The CAA will add 15mm or so to the entire distance. Which means I need to focus forwards 15mm more to hit my focus plane.
Again, I decided to put my reducer AFTER the CAA as that just made sense to me. Why would I want to rotate my camera independently to my reducer? It semes I’m incorrect, and the CAA should go after any reducers/flatteners/barlows used. Still, it took up a lot of the focusing distance and I could image on some telescopes that could cause issues.
Though you will take out any spacers you need to put in accessories like filter wheels. The ZWO ones have a specific thickness so they fit in nicely where a spacer would’ve been.
So I would recommend measuring where your focal plane is. Just take a tape measure from the end of your focus tube, to where your camera sensor is when the telescope is in focus. That’s your focal plane. Assuming you’re keeping the same reducers or barlows, your camera will roughly need to be at this distance. So just see how much forward racking you have remaining.
ZWO CAA Pricing & Conclusions
I imagine this product would be absolutely ideal for those with permanent setups in observatories, but of course it has a use for every imager. It really reduces the hassle in manually rotating and then trying to match rotation. There have been more than one project I’ve worked on where I’ve rotated the camera but never got it quite bang on again. Meaning I have to crop out misaligned edges of the frame.
So I mentioned earlier its price also. At the time of this review the ZWO CAA is retailing at £299. I found this to be quite steep at first for a rotator. But as it turns out, it’s actually the cheapest or among the cheapest rotators on the market now. It enters a niche yet competitive market here, and I think it puts on a good show. When compared to its competitors, it’s a good price point.
The overall excellent build quality, thick machined threads and sturdiness, with its smooth operation, consistent and accurate angle matching and quiet operation makes the ZWO CAA a good product in my opinion. No, I don’t think it’s going to be for everyone, but for those looking for a reliable rotator, this works.
It has some drawbacks that I found. Then again, no product is ever perfect, and all our arrangements are slightly different. That’s why lots of individual reviews are always great.
If you fancy buying one, you can use my links. That way, I will get a few pennies to help running the channel and it comes at no extra cost to you.
Thank you very much for reading, I hope you find this review helpful in your purchasing decision, and if you want to, feel free to watch my video review on the matter.
Until next time, clear skies. Keep looking up and keep them cameras clicking.
ZWO CAA Video Review
If you’d prefer to watch the review, you can enjoy it on my YouTube channel!