Image Quality & Performance

On paper the iPhone 6s Plus specifications don't look too impressive next to some of the high-powered Android competitors but, as usual, Apple is getting the most out of the hardware resources and with its new A9 processor in general operation the 6s Plus is one of the most responsive devices we have used.

The camera app can be opened from both the home or lock screen in approximately one second and the burst mode still operates at 10 frames per second. As before you can select and save your favorite frames in a burst in the gallery app. Shot-to-shot times are impressively fast as well. You can tap away at the shutter button as fast as you can and the iPhone will keep up without any delays.

Like in the predecessor the on-sensor phase detection helps achieve a fast and precise AF. In good light the focus locks on almost instantly and we have not had any false positives in our hundreds of sample shots. In lower light the AF can slow down noticeably but it's all well within acceptable limits. We'd call battery life average. On a day with lots of shooting and other normal smartphone use you'll have to look out for a power outlet sometime in the evening. If battery life is a priority there are better options out there but the iPhone is no worse than most.

Daylight, Low ISO

In good light the iPhone 6s Plus usually delivers consistently good exposure and images with slightly saturated and warm but pleasant colors. As usual on small-sensor smartphone cameras dynamic range is a limitation but the iPhone is just a touch less prone to highlight clipping than many of its rivals. 

When zooming in to 100% don't look quite as good. Where the predecessor 6 Plus captured excellent pixel-level detail with its 8MP sensor the 6s Plus and its 12MP chip record larger image but at a 100% view detail looks smeared and much more processed. There is also quite a bit of noise in the mid-tone areas.

ISO 25, 1/353 s
ISO 25, 1/503 s
100% crop
100% crop

As you can see in the samples below skin tones are natural but image detail is not quite up with the best. Fine detail is being lost through noise reduction, even at base ISO. As you would expect, in the shadow areas of an image this is more noticeable than in the brighter areas. 

ISO 25, 1/176 s
ISO 25, 1/50 s
100% crop
100% crop

When shooting with the sun or other bright light sources inside or just outside the frame the iPhone 6s Plus camera is a little more prone to producing lens flare and artifacts than we would like. Like almost all smartphones the iPhone is prone to highlight clipping but deals a little better with high-contrast scenes than some competitors. 

Overall, like its predecessors the iPhone 6s Plus does an excellent job in terms of exposure, tonality and color, making images a pleasure to view on the phone screen or your computer. However, in terms of image detail and noise the Apple camera cannot quite keep up with the best in class.

ISO 25, 1/157 s
ISO 32, 1/50 s
100% crop
100% crop

Low light, high ISO

As we've already seen on the iPhone 6 Plus, in low light the new model uses very slow shutter speeds to keep the ISO down in low light. In normal shooting the camera would not go above ISO 640 in our test, even for the darkest scenes. This works pretty well and thanks to the very efficient optical image stabilization blur caused by camera shake is hardly an issue.

Tonality, color and exposure tend to be good across the ISO range, only images captured in very low light could occasionally be a little brighter. Below ISO 400 luminance noise is clearly visible but pleasantly finely grained and therefore not too intrusive. At higher sensitivities though, it becomes noticeably stronger and more smeared. Hints of chroma noise start creeping in at ISO 400 as well, but generally chroma noise is very well under control. 

Overall in low light the iPhone 6s Plus does a very good job in terms of exposure and color. Thanks to keeping the ISO at low values, detail is comparatively good but at ISO 400 and higher some of this advantage is cancelled out through strong noise and noise reduction.

In the ISO 64 sample below on the left some loss of detail is noticeable but edge detail is still very good. The image on the right was taken in a dark basement but thanks to a very slow shutter speed the camera only cranks ISO up to 125. The image is a little soft but noise is still well controlled.

ISO 64, 1/17 sec
ISO 125, 1/4 sec
100% crop
100% crop

The white balance system deals well with the artificial light situations in the samples below. As you can see in the 100% crops fine detail suffers but noise is not very intrusive and edge sharpness is well preserved, despite the slow shutter speeds.

ISO 125, 1/8 sec
ISO 160, 1/8 sec
100% crop
100% crop

The ISO 200 image below on the left still looks decent at a 100% view but on the right you can see that at ISO 400 things are starting to slightly fall apart. Suddenly noise levels have increased a lot and at the same time detail is seriously suffering. To be fair though, this image was taken in pretty low evening light and most other smartphones would have selected a higher ISO setting to capture it.

ISO 200, 1/33 sec
ISO 400, 1/4 sec
100% crop
100% crop

To capture the night scene below on the left the camera selected ISO 640 which is the highest value we've seen in normal shooting. You can see a lot of noise and the effects of noise reduction but at 100% the capture actually looks a little better than the ISO 400 shot above. Interestingly, for exactly the same scene plus a moving subject the camera selected a much higher ISO 2000 setting, as you can see in the image on the right. Given that detail actually looks a touch better than on the left exposure and the moving person in the frame looks strangely pixelated we would assume that Apple is again, like on the 6 Plus, using an image stacking night mode when moving subjects are detected in a night scene.

ISO 640, 1/4 sec
ISO 2000, 1/17 sec
100% crop
100% crop

Flash

Smartphone flashes tend to be emergency illumination devices rather than creative tools and the dual-LED variant on the iPhone 6s Plus is no different. That said, when the light gets low the 6s Plus usually manages a decent exposure although there can be some variation in brightness, depending on subject distance. 

The dual-tone LEDs helps achieve pleasant skin tones and, as in general low light photography, the camera tries to keep the ISO low and usually around a value of 100. This results in decent pixel-level detail. In low light the shutter speed appears to be a fixed 1/17 sec but increases when you shoot in brighter conditions and only use the flash as a filler.

ISO 125, 1/17 sec
ISO 150, 1/17 sec
100% crop
100% crop