By Bob Snow
The iPhone 6 camera has the same 8 megapixel count as the 5s and this has spec-happy geeks bashing the phone. There are compelling reasons for going lower and I will try to lay them out.
Small sensors can suffer when they have a high pixel density. The sites that gather light become very small and they typically sacrifice low light performance. Low light performance gets traded off for higher resolution and even this becomes an issue with small sensors. No matter how high the resolution of the sensor, lens resolution comes into play much more when the sensor is small. If the sensor is small enough, the lens will not have nearly enough resolving power to take advantage of all the pixels. You need a bigger sensor for that. The image can only be as sharp as the light coming from the lens and that will most likely be the limiting factor. Think of a tiny sensor with a trillion pixels. Lens resolution will be the limiting factor.
There is another reason the iPhone uses an 8MP sensor. Post processing. The latest iPhone 6 does a hell of a lot of post processing. According to Apple, “Auto image stabilization makes up for motion blur and hand shakiness by taking four photos with a short exposure time. Then the best parts of those photos are combined into one image with as little noise, subject motion, and hand shake as possible.” Apple is even using multiple exposures to eliminate noise in post processing. That is a lot of work, even for the powerful 64-bit A8 processor. The more pixels, the more processing that needs to happen. HDR is another feature that requires post processing. Multiple exposures are taken and then combined to create an image with greater dynamic range. Then there is burst mode. The camera takes up to ten images per second and then compares them all to select the best image. The biggest change to the camera of the iPhone 6 is the use of paired “focus pixels” which allow for phase detection auto focus. This is faster than contrast detection and provides big improvements to video and faster still shot focusing. Think about all of the post processing this phone does to the images, all without a hint of delay.
Evaluations of the iPhone 6 camera have generated stellar reviews. The number of pixels is only a small part of the reason a photo turns out well. Apple’s strategy in dealing with the limitations of a tiny phone camera is a good one. The fastest lens and largest sensor they can fit with big enough individual sites to perform well in low light. Add to that a staggering amount of post processing to enhance the image quality. Look at the reviews and not just a few specifications when you consider the performance of a camera phone.