When you see adverts for digital cameras, the makers normally put the megapixel count front and center - this camera has 15 megapixels, this one has 25, this one only has 5. However what exactly does the megapixel (MP) count in a camera mean, and how important is it?
Megapixels are simply a measure of how many pixels the camera can capture in a single image - a camera with 8MP will take photos that are 3264 pixels high and 2448 pixels wide. 3264 x 2448 = 7,990,272, which for the sake of ease is rounded up to 8MP. So the larger the megapixel count for the camera, the more pixels each image will have.
This suggests that the more megapixels, the better the camera, right? Seems that way, but it’s not actually the case. While megapixels make for a very nice marketing point, the truth is that a digital camera’s sensor is far more important - this is what really allows the camera to take good photos.
The sensor is the part of the camera that captures the light of what the lense is ‘seeing’, and turns it into a digital image. The size of the sensor is extremely important - the larger the sensor, the more sensitive it will be, the more information it will capture, and the better the photo will turn out. This is why even an older compact camera will take better photos than many smartphones - the phone may have a bigger megapixel count, but the compact has the space for a bigger sensor. This means that the compact camera will take clearer, more detailed photos.
Sensor size also affects how the camera performs in low light - a larger sensor means the camera can ‘capture’ more light from the scene, allowing for a better, more balanced low light photo. This is the reason many smartphones are terrible at taking pictures in anything less than daylight. For more information, see this TechHive article on Demystifying Digital Camera Sensors.
Going back to megapixels, it may help to think of the whole situation like a painting - the megapixels are the canvas, and a larger canvas means a bigger potential surface area to fill. However this is nothing without a good brush and some high-quality paints - this is the sensor.
When choosing a digital camera, it is better to concentrate on the 'quality' of the megapixels rather than 'quantity'.
So when do you want a high megapixel count in your camera? Well it depends on what you intend to do with the photo. Most people will just print off a standard 4x6 picture, or upload it to social media. For these small-scale uses, a smaller ‘canvas’ will be perfectly sufficient - no more than 8MP is really needed. However if you’re wanting to print the photos in larger formats - such as posters - you’re going to need a far bigger ‘canvas’. This is when you want a camera with a megapixel count of 15 or more - though once again the quality will depend on having an image sensor large enough. If you want more info, Tom's Guides has a great article on How Many Megapixels Do You Really Need?
All of this info is no doubt really complicated, and seems like it may make choosing a good digital camera even *more* complicated than it was before. However you now know the secret to picking a good camera - look at the sensor size, and judge that before anything else. The megapixel count is largely just marketing - very few cameras on the market right now won’t have the megapixels to take good personal photos.
Hopefully we’ve helped explain some of the complexities associated with digital cameras - now armed with knowledge about the power of camera sensors, you can take a look at our list of best digital cameras.