Why the iPhone 6 Plus Camera isn’t better than the Note 4 vs Galaxy S6 Edge

May 14, 2015

The iPhone 6 Plus has one of the best cameras of any phone on the market. It trails behind the Note 4 and Galaxy S6 Edge in DxOMark rating. I wanted to know what makes the iPhone 6+ camera such a good one, and at the same time I wanted to know why it fails to beat the S6 Edge and Note 4, in which areas and by how much.

The Apple iPhone 6 Plus rear camera was highly praised for its image quality. The camera uses a 1/3.0″ (4.89 x 3.67mm) 8MP BSI sensor to stat with. This sensor is slightly larger than that of the iPhone 6 (1/3.2″ 4.54  x 3.42 mm), but the same size as the iPhone 5S. At that point, the iPhone 6 Plus sensor is still smaller compared to some of what the competition offers. For example, the Sony Xperia Z3 which features a 1/2.3″ (6.17x 4.55 mm) size sensor.

If we look at DxOMark mobile rating table, we can see that the Xperia Z3 in the 6th position, below the S5 and the iPhone 6. On of the reasons the Z3 fails to outperform the 6+ is due to its smaller pixels (1.2 vs 1.5 micron). If Sony has used a 8MP sensor instead of 20.7MP, we might have seen completely different results. The Z4 also has a faster f/2.0 aperture, faster than the f/2.2 aperture of the 6 Plus. Overall, the Z3 had better potential, but it fails short because of the higher pixel density. I don’t know why Sony has decided to go with such high resolution. Even in APS-C size sensor DSLRs, most companies prefer to use a lower resolution promote better high ISO performance. So having 20.7MP resolution for such a tiny sensor is just ridiculous.

Apple stayed with the optimal resolution. I say ‘optimal’ because is seems that it’s the best balance between resolution and image quality, what the resolution that most consumers want to have with good image quality. So the iPhone 6 Plus actually features the same sensor size and sensor resolution, the same F2.2 aperture – so how come the S6 performs better than the 5S?

There is a noticeable different in image quality between the iPhone 6 Plus and iPhone 5S as you can see in this comparison on cnet.com. The iPhone 6 Plus produces sharper and more detailed image. It also performed much better in Low light, but that’s due to its optical image stabilization. You can see that both images were taken at different ISO sensitivities. Of course the photographer doesn’t need to care about that, as long as the camera can perform better in low-light.

So is it just because of the image stabilization that the iPhone 6 Plus was able to outperform the 5S? Well, I can’t answer that question. I don’t know how the test was made and if the cameras was used on a tripod and show in the same settings.  If they are both use the same lens and sensor, there shouldn’t be a difference in image quality, just i situations where the OIS is useful.

Let’s take a look at the iPhone 6 Plus vs iPhone 5 specs first:

iPhone 6 / iPhone 6 PlusiPhone 5S
Rear Camera Sensor1/3.0" (4.89 x 3.67 mm)
8 megapixels
BSI
3264x2448 pixel resolution
1.5 micron pixels
1/3.0" (4.89 x 3.67 mm)
8 megapixels
BSI
3264x2448 pixel resolution
1.5 micron pixels
Lens29mm equivalent
f/2.2 maximum aperture

Five-element lens
Hybrid IR filter
Sapphire crystal lens cover
29.7mm equivalent
f/2.2 maximum aperture

Five-element lens
Hybrid IR filter
Sapphire crystal lens cover

* iPhone 5 rear camera has 31mm equivalent focal length
Burst Mode10 fps + AF10 fps + AF
TimelapseYesNo (available via update to iOS 8 or a dedicated app)
Optical Image StabilizationiPhone 6 Plus: Yes (using a built-in gyroscope)
iPhone 6: No
No
Face DetectionYes Improved! (faster and more accurate)Yes
Video StabilizationYes Improved! (built-in cinematic video stabilization)Yes, basic
AutofocusYes Improved!

Has a new built-in cinematic video stabilization that further stabilizes video shooting while moving (e.g. shooting while walking)

Hybrid AF - Added on-sensor phase-detection AF sensors ("Focus Pixels") with contrast-detection AF, which dramatically improve AF speed, especially when shooting moving subjects, even in burst mode.
Basic video stabilization

Contrast detection AF only
FlashDual LED True Tone FlashDual LED True Tone Flash

(two LED lights with different color tones, one warm, other cold - mix the two to get a true-to-life color rendering under various type of lighting that have different color temperatures)
Video1080p 60 fps / 30 fps
720p 120fps / 240fps (slow-mo)

+ Continuous AF in video (Taking advantage of the phase-detection pixels)

+ an option to apply slow-mo to portion of the video and output as a new or apply to a portion of an existing video.
1080p 30 fps
720p 120fps (slow-mo)

No continuous AF during video recording

I did went back to see the imaging results on DxOMark test. The iPhone 6 Plus had better noise and artifact performance, all the other parameters measured are the same. also DxOMark mentioned in their review that the main difference was due to the OIS, which helped the iPhone 6 Plus perform better in low-light. But overall the image quality is the same. This OIS is most probably the main reason why the iPhone 6 Plus is positioned one rank about the iPhone 6.

An optical image stabilization is crucial for obtaining high quality images in low-light. Let’s take a loot at two sample images and I’ll explain why the Optical Image Stabilization is such a crucial feature for low-light photography.

This photo from Flickr was shot with the iPhone 6 Plus at f/2.2, 1/4 sec shutter speed and ISO 500.

IMG_3432
 

The second photo was shot using f/2.2, 1/4 sec shutter speed and ISO 320

5 Rabbit Vida y Muerte
The reason why the OIS on the iPhone 6 Plus is so important it’s because it minimize image blur due to camera shake when shooting in slow shutter speeds. In iOS 8 you have the option to manually set the shutter speed in the camera app as well.  You can see that those iPhone 6 Plus sample image turned up very sharp. There are tons of low-light sample images available on Flickr for you to inspect.

The Optical Image Stabilization won’t help in situations where you want to freeze the subject.  For that you’ll need to use a faster shutter speed, and this will reduce the amount of light that reaches the sensor.  The optical image stabilization on the 6+ is probably the best feature of the 6 Plus that helps promote better looking low-light photos. Some of the images that I’ve seen taken with the iPhone 6 Plus might not be even possible without the image stabilization.

I’ve written an in-depth analysis of the iPhone 6 Plus optical image stabilization, which you can read if you want to know more about it. The OIS should give you around 2 to 3 stops advantage. This means that the sensor will be able to receive up to 3 times the amount of light compared to a non-stabilized camera. So in other words, you you can shoot with the iPhone 6 Plus using a shutter speed which is up to 3 stops slower and still get the same sharp results (Results may very).

Now, both the Samsung S6 Edge and Note 4 have an optical image stabilization mechanism, so what helped them outperform the iPhone 6 Plus camera, which we can see, it’s quite an impressive one.

Let’s take a look at the specs first.

iPhone 6 PlusGalaxy S6 EdgeGalaxy Note 4
Sensor8 megapixels
1/3.0-inch (4.89 x 3.67 mm)
BSI

4:3 aspect ratio
16 megapixels
Sony Exmor IMX240
1/2.6-inch
BSI

16:9 aspect ratio
16 megapixels
Sony Exmor IMX240 (used in the Qualcomm Snapdragon 805 variant) / ISOCELL
1/2.6-inch (5.79 mm x 4.01 mm)
BSI

16:9 aspect ratio
Max Image Resolution3264 x 2448 pixels5132 x 2988 pixels5132 x 2988 pixels
Pixel Size1.5 µm pixels1.12 µm pixels1.12 µm pixels
Lens29mm equivalent focal length
f/2.2 maximum aperture

Five-element lens
Hybrid IR filter
Sapphire crystal lens cover
28mm equivalent focal length
f/1.9 maximum aperture

Largan Precision Optics

Six-element lens (plastic)
28mm equivalent focal length
f/2.2 maximum aperture

Largan Precision Optics

Six-element lens (plastic)
Image StabilizatoinOptical (using a built-in gyroscope)Optical (Smart OIS)Optical (Dual Axis Gyroscope)
Video StabilizationYes (cinematic video stabilization)YesYes
AF SystemHybrid
phase-detection AF ("Focus Pixels") with contrast-detection AF
Hybrid
phase-detection AF ("Focus Pixels") with contrast-detection AF
Contrast-detection
FlashDual LED True Tone FlashLEDLED
Video1080p 60 fps / 30 fps
720p 120fps / 240fps (slow-mo)

+ Continuous AF in video (Taking advantage of the phase-detection pixels)

+ an option to apply slow-mo to portion of the video and output as a new or apply to a portion of an existing video.
2160p(4K) 30 fps
1080p 60fps
720p 120fps
2160p(4K) 30 fps
1080p 60fps
720p 120fps
IR white balance
detection
NoYesNo
HDRYesYes
- Real-time HDR
Yes
- Real-time HDR
Tracking AutofocusYes
Yes

(fast tracking auto-focus function)
?
RawNoNoNo

Let’s see in what areas the iPhone 6 Plus did worse and better than the Note 4 and S6 Edge on DxOMark tests.  The iPhone 6 Plus did the worst in RGB Texture acutance (tungsten light) test (S6 1st, Note 4 2nd), in the Edge sharpness test the iPhone 6 Plus was also last overall, Note 4 was the best, followed by S6. In terms of image noise, the iPhone 6 Plus had the worse high ISO performance, the S6 was the best, followed by Note 4 (source).

We can understand that in terms of texture, sharpness and low-light performance, the iPhone 6 Plus did worse than the Note 4 and Galaxy S6 Edge.

So what we can see is that although the iPhone 6 Plus has larger pixels, the S6 and Note 5 that have both smaller pixels than the 6+, were able to outperform it in low-light.  The S6 Edge lead the low-light tests because of its f/1.9 aperture and OIS, this combination is just hard to beat.

This is why most phone manufacturers bring their new phones with a faster aperture lens. All of this phones, the iPhone 6 Plus, the Note 4 and Galaxy S6 Edge, all use a fixed-aperture lens. This means that the aperture doesn’t change. A faster aperture lens might have a negative impact on sharpness because of diffraction. Having said that, the S6 Edge shown to perform amazingly well with that very fast aperture. Let’s not forget that the Note 4 and the S6 Edge have a significantly higher resolution as well. So not that you are giving up on resolution to enjoy better image quality, you actually gain more.

This is what the Galaxy S6 Edge is such a stellar performer, and with all that in mind, we can see what it’s positioned first in DxOMark. We can expect the iPhone 7 to improve in that respect and have a faster aperture lens. New sensors also greatly improve image performance in each new generation.  I expect the iPhone 7 to have faster optics, new sensor and higher resolution – at least that what Apple had to do at least to keep up with the competition.



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