The Apple iPad Air 2 Review
by Joshua Ho on November 7, 2014 9:30 AM EST- Posted in
- Tablets
- Apple
- Mobile
- iOS
- ipad Air 2
Camera
For better or worse, the camera on a tablet has become increasingly important. While there was a time when the cameras on tablets were solely used for video calls and similar functions where quality was of relatively low importance, there’s been a clear shift in the other direction. While I don’t think anyone is going to use their tablet as a primary camera, there is a level of convenience that comes with it. I’ve definitely found it to be rather intensely uncomfortable to use a tablet as a camera at all as it’s the furthest thing from inconspicuous. This brings us to the iPad Air 2, which brings the first notable camera change to the iPad line since the iPad 3, as seen below.
| Rear Facing Camera Comparison | |||||||
| Sensor | Resolution | Aperture | Focal Length | ||||
| Apple iPad Air 2 | 8 MP | 3264 x 2448 | f/2.4 | 3.3mm | |||
| Apple iPad Air | 5MP | 2592 x 1936 | f/2.4 | 3.3mm | |||
| Apple iPad 4 | 5MP | 2592 x 1936 | f/2.4 | 4.3mm | |||
| Apple iPad 3 | 5MP | 2592 x 1936 | f/2.4 | 4.3mm | |||
| Apple iPad 2 | 0.7MP | 960 x 720 | f/2.4 | 2.0mm | |||
| Apple iPad mini | 5MP | 2592 x 1936 | f/2.4 | 3.3mm | |||
While the iPad Air 2’s camera does have an eight megapixel output image, it’s important to distinguish this from the iPhone line as the sensor is noticeably smaller than what we see on something like the iPhone 6 and 6 Plus. Instead of 1.5 micron pixels, this gives us 1.1 micron pixels. In addition, the camera lacks PDAF, so focus times will definitely take a fall as a result. On the flip side, this also means no camera hump on the back.
While focus times are one thing, the difference in pixel sensitivity is likely to be the biggest difference. In casual testing, the ISO of the rear-facing camera goes between 25 and 800 ISO, and the front-facing 1.3MP camera will vary between 50 and 2000 ISO. As the tablet lacks optical stabilization, Apple has capped exposure time to a maximum of 1/15 seconds similar to what we see with the iPhone 6.
As one might guess, this difference in sensitivity doesn’t actually make for a significant difference in daytime. While 1.1 micron pixels are relatively small, daytime resolution isn’t all that far off from the iPhone 6. The extremely low sensor gain means that the impact of lower pixel sensitivity isn’t all that significant. It’s clear that the A8’s ISP does a good job of preserving detail while removing noise as we don’t see loss of detail in low contrast areas and noise in general is hard to see outside of the sky.
HDR is also quite good as one might expect, with no perceivable halos or ghosting effects from moving objects.
Unfortunately, in low light we see the weakness of the smaller pixel sizes as a significant amount of noise creeps in. This is especially obvious in preview as noise reduction doesn’t seem to be running at that point. Given the amount of noise in the preview, it’s still quite impressive how Apple manages to make the best of a system that isn’t really designed for low light photography. While a great deal of low-contrast detail is gone, there is a great deal of detail preserved and such images definitely good enough to put online if necessary. I don’t see any major color noise in the image, and luminance noise strikes a good balance between excessive blurring and obvious speckle.
In video, we see a similar pattern. On the whole, the iPad Air 2 benefits from the shared ISP from the iPhone 6’s A8 SoC as the EIS solution is surprisingly effective at suppressing high-frequency shaking. In daytime, detail in video is surprisingly good and quite close to what we see with the iPhone 6 line of devices. The one noticeable weakness is that due to the lack of PDAF, it’s necessary to stop and tap to focus on specific objects to maintain detail. There is auto-exposure, but video performance overall is a bit weaker than what one would get from the best smartphone cameras available. We see the same 17 Mbps bitrate encoded with H.264 high profile here as on the iPhone 6.
The iPad Air 2 also has a slow motion mode, which does 120 FPS at around 31 Mbps encoded with H.264 high profile and plays back at 30 FPS. The resolution is 720p, which is in line with other iOS devices for slow motion.
Once again, in low light we see the weakness in the smaller sensor. There’s a great deal of noise visible throughout the video, although there is an acceptable amount of detail and frame rate remains relatively high.
Overall, it’s hard to really find fault with the camera. While the smaller sensor size and lack of phase-detect focus does make for worse images, the camera can actually take good photos in daytime and usable photos in low light. Video follows a similar pattern as well. As said before, this camera is unlikely to be of any value as a primary camera due to the tablet formfactor. However, for applications that need a camera this should be quite serviceable.
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name99 - Friday, November 7, 2014 - link
Roughly Haswell IPC is equal to Apple IPC. There are lots of caveats to this --- Apple does better on Geekbench, Intel does better on SPEC (probably because they have a superior memory system). Intel also have, to be fair, a much more mature compiler, while Apple can probably squeeze another 10% out of LLVM for ARM64 over the next year or two, along with some improvements to the SPEC numbers when their long awaited polyhedral optimizations finally go mainstream.I used to think Apple would ramp to higher frequencies, now I think a different trajectory is more likely. An Intel CPU is a bundle of many capabilities, and the CPU part is only one of these. There's also, for example, the turboing subsystem, and the profiling/debugging subsystem. My guess is that they are (even though they have said nothing about it) headed for the same sort of HSA future that AMD talks about.
I expect over the next few years, much Apple work will go into this sort of less than sexy infrastructure, stuff that Apple won't talk about much (if at all) and it will only make its appearance in things like better XCode tools and much less overhead to transfer code and data between CPU and GPU. Looking at the competitive landscape, Apple look like they could get away with an A9 improvement that's to the A8 as the A8 is to the A7 --- a steady 25%, one third from compiler, one third from another 100 or 150MHz boost, and one third from more tweaking of the CPU.
It's possible that this is indeed what we should expect because I'd guess that Apple's A-team for CPU design is hard at work on the AWatch project, and probably following the same strategy as we saw with CPUs --- the S1 will probably be a good but not spectacular SoC, something reliable to get the project rolling, the equivalent of A5. S2 will presumably be a substantial jump, with all the less risky optimizations they couldn't fit into S1, while S3 will knock it out of the park, taking the risk of project slippage to make use of every good idea the team has.
If this theory is correct, It may not be until A10 or so, as the team has hired more people and the watch project becomes more stable, that we get a rethinking of the phone/tablet CPU.
[Of course by then, who knows, maybe Apple will have announced iDust and mote CPUs will be what their CPU A-team are working on?]
anquietas - Friday, November 7, 2014 - link
Good perspective! This sounds lIke exactly how Apple would operate.iwod - Saturday, November 8, 2014 - link
This. Most people when comparing ARM64 SoC to Intel often fail to count the difference between the software ecosystem. Intel had much more engineers and years of optimization in libraries, and compiler. There are still quite lot of work to do on ARM64 and LLVM.JoshHo - Friday, November 7, 2014 - link
While we haven't included the Surface Pro 3 in comparisons as it's a much more expensive device, all of the tests in this review and more have been released to Bench where you can compare the two SoCs.ABR - Friday, November 7, 2014 - link
Just got back from checking the iPad Air at a store, and the performance was disappointing to say the least. I've got an iPad 2, and I keep reading about these leaps and bounds in the SOCs each year, but when it comes to a real-world task like opening the Mail app or paginating a novel in iBooks, this supposedly mind-blowingly smoking device is only incrementally faster than my 2nd gen clunker. What gives?I thought maybe everything was being bottlenecked by the flash access, but Josh tested that too and of course it looked way ahead of earlier hardware in that area too. iOS slowdowns? I'm running 7 instead of 8 on the Air 2, but that's only one generation behind.
Anyone have any idea what the deal is?
rUmX - Friday, November 7, 2014 - link
You need to be performing more intensive tasks to see the huge peperformance differences, as benchmarks show. Opening mail is not very demanding.ABR - Friday, November 7, 2014 - link
I guess you're saying maybe there's a floor effect with Mail opening given by the animation timers if nothing else, but how do you explain iBook pagination? That takes several seconds and seems to be computatin limited.Sushisamurai - Friday, November 7, 2014 - link
If u can't tell a difference, then maybe u should hold onto your iPad 2. I sold my iPad2-32GB wifi model for $200, just to upgrade to this Air 2. My iPad2 was stuttering and dropping frames for the apps I was using (also on iOS8). This Air 2 is absolutely amazing compared to the iPad2 - some of my daily apps can load, and reload (after downloading a minor update), before my other iPad2 finishes loading LOLABR - Saturday, November 8, 2014 - link
Maybe it's iOS 8 then. Good way to sell hardware. The big performance drop going to 7 is one of the reasons I'm not going any further yet. I'd get the Air 2 for the weight, retina, and fingerprint, not the SOC, but the way it runs hot is a big downgrade.Streamlined - Friday, November 7, 2014 - link
FYI, I was doing some financial analysis on Apple and the iPad Air 2 cost structure and I'm estimating that the "Apple Tax" on these is probably only a little more than $100 per unit on the 16gb wifi model.Read the details at www.perezonomics.com