Around the turn of the millennium when digital cameras were first becoming popular megapixels mattered. The average digital camera back in 1999 had less than 2 megapixels (MP), which wouldn't have been enough pixels if you needed to produce a print ready image that filled an A4 page. A 300 dpi image at A4 size would need to measure 2,480 x 3,508 pixels, which is a total of 8,699,840 pixels, or just over 8MP.
These days some compact cameras boast as many as 16MP, while you can get more than 24MP on an SRL. Phone cameras are also packing in the megapixels. The Samsung Galaxy S4 offers a 13MP camera, and the Galaxy S5 will offer a 16MP camera. The Sony Xperia Z2 has a 20.7MP camera. But the camera on Apple's flagship iPhone - the iPhone 5s - only offers 8MP. Does this mean that Apple's iPhone camera is worst than other phone cameras that offer more megapixels?
The answer is no, and we're going to explain why.
Dispelling the megapixel myth
It's wrong to think that the more megapixels your sensor has the better your image will be. Of course that doesn't stop various camera phone and camera manufacturers from promoting their products as superior due to the number of megapixels they have packed in. These manufacturers are hoping to fool you into thinking that the number of pixels has something to do with image quality. People like to see a number that indicates whether something is better so many are being taken in by this ruse.
The number of pixels means nothing if the manufacturer has achieved it by cramming them onto a small sensor, as is the case with many modern camera phones. In some cases, in order to achieve more pixels, manufacturers are making those pixels smaller.
A good camera will have the right amount of pixels for the size of the sensor.
It's the size of the pixels that counts
Rather than make the pixels smaller in order to increase the amount of pixels that can be fitted on the sensor, Apple increased pixel size to 1.5µm (from 1.4µm - those measurements are in micrometers) and kept the pixel count the same by using a 15% larger sensor.
As Apple's Phil Schiller said in the keynote announcing the new iPhone 5s: "Bigger pixels equal better picture". Increasing sensor size and pixel size makes a big difference to low light sensitivity and noise.
Why the camera sensor matters
The sensor is what captures the light and converts what you see into an image, it determines image size, resolution, lo-light performance, depth-of-field, dynamic range, and basically how good your photos look.
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