Cubot Rainbow 2 smartphone

As you may have guessed, a fairly large part of this review will focus on comparisons. Comparing devices based on the same processor and with the same amount of RAM and flash storage isn’t entirely fair, but there are still some differences.

Specifications:
Color — Black, White, Gold, Blue, Red
Processor — MTK6580, 4 cores
GPU — Mali-400 MP
Operating system — Android 7.0
Memory — 1 GB RAM, 16 GB flash storage.
Display — 5 inches, 1280x720 resolution
Network type GSM：2G: GSM 850/900/1800/1900MHz
WCDMA：900/1900/2100MHz
Wireless interfaces — Wi-Fi: 802.11b/g/n, Bluetooth 4.0
GPS, A-GPS
Memory card slot — MicroSD, supports up to 256 GB.
Audio output/microphone — 3.5 mm jack.
SIM card type — 2 micro SIM cards
Front camera 2 MP + flash
Main camera 8 (13) MP + 5 MP + flash
Event indicator
Battery 2350 mAh
Dimensions 144x72x8.3 mm

As I mentioned in previous reviews, most Chinese phones are essentially “construction kits”: the manufacturer assembles a new device from different “building blocks,” resulting in a fairly wide range of models. Add more memory, and you have another model; replace the camera, and there’s another one; increase the battery and the case, and it’s a new model again, and so on.
This smartphone is no exception. Looking at the specifications, you can immediately see what has changed compared with the previous version:
Android is now version 7.0 instead of 6.0
There are now three cameras in total, compared with two before.
The battery is now 2350 mAh, up from 2200 mAh
The front camera now has a flash
A-GPS has also been added; the first version didn’t have it.
A blue model has been added.
Memory cards were supported up to 32 GB; the limit is now 256 GB.

The device comes in exactly the same box as the previous one. The packaging is very sturdy, so at least that’s something to be happy about.


The package includes:
1. Cubot Rainbow 2 smartphone
2. Charger (power adapter)
3. USB-to-microUSB cable
4. Phone case
5. User manual and warranty card.


The top half of the packaging was separated from the bottom by a small piece of cardboard, which also serves as an extension of the manual. It even reminded me of Ford and his production optimization—though in that case, they used boards from packing crates :)


1. The package included a manual and a warranty card (a booklet). The first might actually come in handy, but the second probably won’t.
2. The manual includes Russian, which is nice.
3. The USB-to-microUSB cable differs from the usual ones only in its connectors. I think it’s good that the manufacturer didn’t switch to the increasingly popular USB Type-C as an upgrade.
4. The charger is rated for up to 1 A, and a full charge takes about 3 hours.


But let’s get to the subject of the review. The phone doesn’t have a shipping film; a thin matte case serves that purpose instead.


As last time, a silicone case was included. And, as last time, it’s rather rough, but comfortable in its own way. It’s comfortable to hold, but it makes the phone much bulkier, and it’s rigid as well.



There are cutouts for the speakers at the bottom. No, more accurately, for the speaker—the other cutout is probably just for symmetry.
There are cutouts for the cameras and connectors at the top. Note that the case noticeably obstructs the microUSB port, so the cable needs to have a long plug.


The phone looks noticeably better without the case. There is one small caveat, though: the screen protector is glossy—very glossy, I’d even say. It looks quite good while you’re using it, until you leave your fingerprints all over the screen... I would have preferred a less glossy finish.


The phone is quite lightweight, partly because it has a low-capacity battery.
But even the previous version, which weighed 165 grams without its case, had an even smaller battery.


It looks like the familiar “black brick.”


This time, though, the edges of the glass are rounded. On the previous model, the glass covered only part of the front panel.


There are the usual three touch buttons at the bottom, and the camera, earpiece, proximity sensor, flash, and notification indicator at the top.


Next, I'll compare the two phones side by side: the previous version and the new one.
Personally, I think the new version looks better, but that's very subjective.



Since the front is black, the proximity sensor is now hidden.


I don't agree with the manufacturer's choice of finish for the back cover, though. I think everyone (or at least most people) has seen a mirror. Now imagine it in black.
Yes, the back cover is practically a mirror, but it's also quite slippery. The phone looks like a more expensive model in your hand, but it sure shows fingerprints....


One of the key differences in the new model is the addition of a second camera. The manufacturer says it's meant to create a blurred-background effect in photos, but I'll test that a little later.


The phones look very similar from the sides and top, with the same buttons and ports in almost exactly the same places.
The trim is a different color, too. It feels a lot like metal, but I'll check that later as well.


There are more differences along the bottom edge: speaker holes have been added. On the previous model, only the microphone was on the bottom edge; on the updated version, it's located where the glass meets the trim.


The screen is nothing special, with a resolution of 1280x720, which is perfectly normal for a budget phone. I had no complaints about the image quality. The only time I've had an issue with a screen (panel) was when dead pixels showed up on a much more expensive device.


The image still looks pretty good when viewed at an angle. It gets lighter, but not by much.


In a side-by-side test, the old and new versions seemed practically identical to me, and both were a little brighter than my Doogee Max.


One more comparison of the two versions.


There's a difference under the cover, too. One good thing is that the manufacturer didn't chase the current trend for side-mounted SIM card slots and kept the old layout. In fact, I tried swapping the card while the phone was on, and it connected, but I wouldn't recommend doing that.
The downside is that the battery is now non-removable, although its rated capacity is higher.


One last exterior comparison of the two phones.


I remove the screws securing the rear frame and housing. Note that the screws are different lengths. As a repair technician, I'm not a fan of that, though it makes no difference to the user.


A general view with the cover removed.


While taking it apart, I noticed some differences in the construction. Usually there's an aluminum frame here, but this one has metal posts. I'll remove the battery to make things clearer.


That's clearer now. Remember I mentioned above that the phone had become noticeably lighter despite having a higher-capacity battery? This phone has no aluminum chassis; its structure is supported by a steel plate with posts. I wouldn't say it's terrible, but in my opinion this design should be less sturdy.


I also mentioned the trim around the perimeter of the housing. When I first picked up the phone, I would have sworn it was metal. There was a certain impression of rigidity and coolness.
But reality showed itself along with the rear frame: it is entirely plastic.
On the other hand, this is common practice, and the execution is pretty good, but it's still worth remembering that the body is completely plastic.

Printed antennas are glued at the top and bottom. The upper one is for WiFi/Bluetooth/GPS, the lower one for GSM.


The bottom cover is also removable. Under it (or, more precisely, on it) is a single speaker, although the openings in the body are arranged symmetrically. This design has become quite common lately.


The smartphone's "motherboard"—the assembly looks very budget-oriented.


The second camera isn't fake; it's real, and it's even connected to the board. All that's left is to test it :)


A couple more photos of the phone's board.


The battery is glued to the steel cover you saw in the previous photos. It's glued at one point, but quite firmly, and it also sits securely in the body. No complaints.


Right at the beginning, I mentioned that I wanted to run a comparative battery capacity test.
I often see reviews testing battery capacity with a USB tester. I'll overlook the fact that the test is done while charging, since the capacity in mAh during charging and discharging a lithium battery differs, if at all, by very little. But measuring capacity without connecting directly to the battery is not a valid test.
I fully discharged the phone, then connected a USB tester and measured how much charge the phone drew. In the photo, I deliberately showed 99% charge rather than 100%, since the phone can reach 100% either a minute after charging is complete or an hour later, but the readings will differ because the phone itself always consumes some power (even when switched off)—or, more precisely, its charging circuit does.
As you can see, it drew almost 2900 mAh. Not bad for a battery rated at 2350 mAh, right?


Now I'll run the test using my own method:
Fully discharge the battery in the phone.
Apply the same current that will be used for the test (1 A in this case).
Measure the battery voltage after 5–10 seconds (3.15 V in my case).
Fully charge it to 4.35 V (if the battery is rated for that voltage).
Discharge it at 1 A down to 3.15 V to get the capacity the phone can use.
Continue discharging to 2.8 V and add that to the previous result to get the total capacity.
Recharge it, putting back at least as much charge as was drawn in the previous step.


The result was a capacity of 2277 mAh when discharged to 3.15 V.
Discharging to 2.8 V gave me another 42 mAh (the screenshot shows two cutoff points: 3.0 and 2.8 V).
So the battery's total capacity is 2277 + 42 = 2319 mAh, just a little below the rated capacity. That's perfectly normal for phones in this category; I'd even say it's good. Sometimes the difference is much greater.

A small clarification: battery labels and specifications always state the battery's total capacity, not the capacity available to the phone.


That's it for the "hardware". Let's move on to the "software"—the operating system and tests.

The home screen and app menu, as well as the app list, are pretty much unchanged from the previous version. Even the look is the same; only the home screen wallpaper has changed.
I'll also note that the option to open the list of running apps by holding down the middle button has been removed. Now you can bring up the app list with a quick tap on the left button.


I praised the developers for leaving the design unchanged, but the software is a little more complicated. The smartphone now runs Android 7.0 instead of 6. In my opinion, with just 1 GB of RAM, that was a mistake. For example, scrolling through the list of apps on the flash drive sometimes causes noticeable lag, and installing software now takes about twice as long. Previously, I could install an app and the screen would only start dimming; now I have to tap it a couple of times to keep it from going to sleep.
But the apps themselves work pretty much the same as they did in the previous version.
The firmware is currently up to date, but the phone refused to update.
The settings menu has also had a few cosmetic changes, but in my opinion it's actually a little more convenient now.


Quite a lot of apps are installed, so almost 5 of the 16 GB is taken up by them alone. The RAM situation is no better: after a reboot and a few tests, the smartphone was using about 550 MB, but in real-world use it was using 770–850 MB, which is quite a lot.


To make up for the rather weak hardware (at least for Android 7), they added an internet software performance booster, but I didn't really notice it doing anything.
On the other hand, there's now an option that prevents the smartphone from locking while you're physically holding it. More on that below.


The smartphone supports several options for “smart” locking. In other words, it won't lock while you're holding it. The manufacturer says it uses various sensors, but I can tell you that it uses the accelerometer and proximity sensor, and detects from the vibrations that the phone is being held. It's a handy feature, in principle, but it requires you to set a password and so on.
If you press the side button after enabling this feature, a message pops up explaining how to lock the phone manually.


You can also set up voice control and prevent the phone from locking at home or when a trusted device is nearby. It's convenient in its own way, I won't argue with that.


More detailed information about the smartphone.
I won't show anything new here, since the platform the smartphone is built on has been well known for a long time.


Here are a few more screenshots from AIDA64.


There are no changes in the number of sensors; it’s still the same bare-minimum set. It’s worth noting, though, that the phone now supports ten-point touch, which is rare even on more expensive models—another difference from the previous version.


Tests. I’ll try to keep this short, especially since there’s not much new here.
AnTuTu version 5 and two versions of version 6.
Performance in version 5 is the same as on the previous model, while version 6 scores about a thousand points lower.


Geekbench also shows the performance we’ve come to expect from this processor.


Performance in Epic Citadel is noticeably lower. Last time the scores were 48.9 and 25.3; now they’re 31.8 and 16.9, about one and a half times lower than on the first version of this smartphone.


Performance in 3DMark and PCMark has either dropped only slightly or not at all: 2023 vs. 1943 and 2813 vs. 2798, respectively, for the old and new versions.


I ran this test for the sake of the statistics, so I won’t comment on the results.


Still, the phone handled Asphalt pretty well. I selected the highest quality settings.


And I was able to play quite comfortably, even though I’m not much of a gamer.


What I really liked about this phone—and what genuinely surprised me—was its excellent Wi-Fi reception. Not so much the speed as the stability and range.
In the worst spot in my apartment, with a lot of reinforced concrete in the way, the phone connected at 2–10 Mbps. In the best spot, it managed 65 Mbps.
Even so, the test showed that data transfer speed in the farthest spot was around 3 Mbps. But moving just a few meters, to a spot with one fewer wall in the way, brought the speed up to 7–8 Mbps. In the first spot, it’s rare for any device to connect to my router at all, let alone maintain a stable connection during testing.


Moving a little closer to the router made no further difference to the speed.
1. A couple of interior walls, about 6–7 meters from the router.
2. The next room.
3. One meter from the router.

As you can see, judging by the test results, I might as well have been standing in one spot the whole time.


Battery. Above, I tested its capacity, which came very close to the claimed figure, but in real-world use things turned out to be more complicated.
During the tests, I was reminded of a well-known episode of the Russian TV show Yeralash, featuring a boy with a watch and two suitcases full of batteries.

So, let’s take it in order. The first tests were more than standard for my reviews: playing Full HD video from a flash drive and YouTube, followed by running the Geekbench test.
Well, the phone lasted about four hours. In the first case it was a little over 4.5 hours; in the second, about 4 hours and 10 minutes. There’s no need to explain the Geekbench test result.


But it wasn’t that simple. I usually use my phone a little during tests, but since I work from home a lot, I often just leave it beside me. So I charged it fully and set it aside. The next day I saw the notification LED blinking. I thought I’d received a text, but no—the battery was down to 10%....
My first thought was, “That’s strange.” Anyway, I charged it and timed how long it lasted. One day! In other words, with just one call lasting about five minutes, no games, and without even turning on the screen, the phone drains its battery in a day.
I ran the test once more, and got the same result (Wi-Fi is on in the screenshot, but it isn’t connected to the router). Then I turned Wi-Fi off, and the phone immediately started lasting much longer. So with Wi-Fi on, you’d have to charge the phone twice a day.
A little later I caught another glitch. I was out with the phone in my jacket pocket. When I took it out, it was warm. Wi-Fi was off, and the battery was obviously draining fast. After something like this, the phone can also take 10–20 seconds to wake up, run painfully slowly, and sometimes even reboot. The Parallel Space app is often the source of the problem.
After these tests, I was reminded of a joke about a super high-tech airplane with swimming pools and bars, and the pilot saying, “Now let’s see if we can get this thing off the ground.”


But there was one thing that worked perfectly well (apart from Wi-Fi): navigation.
At first I was a little disappointed when the smartphone detected very few satellites, but the track test showed that things weren’t so bad—at least compared with everything else.
I turned on log recording, put the phone in my inside jacket pocket, and went for a walk. In the screenshot, the red line shows where I actually walked, and the green line shows where the navigation app thinks I walked. Let's just say that for a fairly small number of satellites, the result is pretty good.


And now I've reached one of this smartphone's features: its cameras—or, more precisely, its additional camera.
First, some general information. When taking photos, there are three options: Standard, Panorama, and Blur. In the last mode, you can adjust the blur, and the control appears after autofocus has finished.


The photo settings are no different from those on most smartphones. The advertised photo resolution is 13 MP, but the camera actually has an 8 MP resolution.
Video is recorded at 1280x720.


The idea behind the smartphone's second rear camera is to add a blur effect, where the background is heavily blurred compared with the subject. Ads always show beautiful photos with this effect, taken using professional cameras. This effect is called bokeh.
Smartphones, on the other hand, use a software blur effect, usually called Blur, which is much simpler. It's very difficult, almost impossible, to reproduce the real effect perfectly. That's because the software needs information about the distance to objects in the background, which is what the second camera is supposed to provide.
But from what I can see, the developers simply blur the background around the subject in software, without paying any attention at all to what the second camera is doing.
I may be wrong, but in my opinion, it's practically impossible to process photos correctly in software at the speed this smartphone takes them.
I tried taking two shots with the background blur set to maximum. In one of them, the second camera was covered. As they say, guess which one had the camera covered and which one didn't :)
Of course, you could say that the subject was too close and the conditions weren't right, but there should still be a difference. Although the distance to the matchbox was much less than the distance to the wall.



Since my work puts me closer to engineers than photographers, I'll venture to give my opinion on dual cameras in smartphones.
I accept that the camera is not only physically connected (AIDA64 reports this), but is also being used. But calculating the effect must take some time, and while I believe in the power of modern processors and that spaceships are traversing the vast expanses of the Bolshoi Theatre all this can be done in software using a stereo camera, smartphone processors (at least in cheap phones) aren't optimized for this task. They just apply a simple software blur that has nothing to do with the way two cameras work.
You could also say that I chose a somewhat unsuitable test, but if you take a shot with the background farther away, the "hardware" effect kicks in, with the background simply out of focus. But you can get that with a single camera, too.

All right, I think we've covered that. Now I'd like to find out what this smartphone's camera can do in general.
As in many other reviews, I compared this phone with the Vernee thor, since it has a pretty good camera.
The photos have been compressed for the site. That's enough to assess color reproduction; for detail, I've made separate crops from the original photos. For a closer look, I've uploaded the originals that I compressed for this review.


Crop in the same order as the photos above.




Here's an attempt at a comparison with Blur enabled, though the subject isn't really suitable.



Some more comparisons.


Crop





Overall, the photo quality is pretty good.


But the Thor is definitely sharper. It feels like Cubot's software is trying to increase sharpness, which creates something that looks like noise. Although the photos themselves look more interesting overall than Thor's.



Now I'll sum things up, starting with the advantages (yes, this device does have some).
Really good WiFi reception.
GPS works pretty well, despite its low sensitivity.
Neat appearance (just my personal opinion).
The battery capacity matches the stated figure.
A case is included.
10-point touchscreen.
Notification LED.

Unfortunately, there are more drawbacks.
Unfinished firmware.
High power consumption that occurs spontaneously.
The Android interface isn't smooth.
Battery life is less than a day with WiFi on.
Occasional software problems, which sometimes even make it take about 20 seconds for the phone to "wake up."
It reboots on its own.
There is an additional camera, but its functionality is practically nonexistent.

My opinion: The manufacturer managed to make a phone that looks pretty good, and I would even have been willing to overlook its rather weak hardware. After all, not everyone needs a phone for gaming. But it seems that's where the good news ends. As soon as it came to the software on this smartphone, things went badly wrong. I don't understand how a device can behave like this on a fairly well-tested, mature platform that's been around for at least a year. It seems the culprit is Android 7.0, along with the manufacturer, who still hasn't released an update. It's simply impossible not to notice that the phone can quickly "eat up" the entire battery charge. In theory, I can imagine a software update coming out, but I don't know whether it would make things any better.

Now, about the cameras. As I wrote in the review, the second camera is supposed to provide depth information, but my test (and other people's too) suggests that while this may have been the intention, it hasn't actually been implemented yet. Strangely enough, in the standard shooting mode the camera takes reasonably good pictures, at least in terms of color reproduction.
The front camera takes pretty good pictures overall. They don't really look like 13 MP shots; I'd say it's closer to 8 MP, and the tests at least showed that this is more realistic. I was pleased to see a flash (light) for the front camera; selfie fans will appreciate it.

What really surprised me in a good way was the very high WiFi sensitivity. I've only come across anything like it a few times.

Comparing the old and new versions showed that this is essentially the same Cubot Rainbow, with a third camera and Android 7 added, then packed into a nicer-looking case.

That's probably all for now. As always, I look forward to your comments on both the smartphone and the comparative battery capacity test.