What Is a Megapixel?

MP Help Determine Camera Quality

As you're looking to purchase a digital camera, one of the most common pieces of camera jargon you'll see touted by manufacturers and expressed by salesmen is megapixel. And it does make a bit of sense -- the more megapixels a camera can offer, the better it should be. Right? Unfortunately, that's where things start to get a bit confusing. Continue reading to answer the question: What is a megapixel?

Defining MP

A megapixel, often shortened to MP, is equal to 1 million pixels. A pixel is an individual element of a digital image. The number of megapixels determines the resolution of an image, and a digital image with more megapixels has more resolution. A higher resolution is certainly desirable in a digital photograph, as it means the camera uses more pixels to create the image, which technically should allow for greater accuracy.

The Technical Aspects of Megapixels

On a digital camera, the image sensor records the photograph. An image sensor is a computer chip that measures the amount of light that travels through the lens and strikes the chip. 

The image sensors contains tiny receptors, which are called pixels. Each of these receptors can measure the light that strikes the chip, registering the intensity of the light. An image sensor contains millions of these receptors, and the number of receptors (or pixels) determines the number of megapixels that the camera can record, also called the amount of resolution.

 

Avoiding MP Confusion

This is where things get a little tricky. While it stands to reason that a camera with 30 megapixels should yield better image quality than a camera that can record 20 megapixels, it's not always the case. The physical size of the image sensor plays the more significant role in determining the image quality of a particular camera.

Think of it this way. A larger image sensor in physical size that contains 20MP will have larger individual light receptors on it, while a small image sensor in physical size that contains 30MP will have very small individual light receptors.

A larger light receptor, or pixel, will be able to more accurately measure the light entering the lens from the scene than a smaller light receptor. Because of the inaccuracies in measuring light with a small pixel, you will end up with more errors in measurements, resulting in "noise" in the image. Noise are pixels that don't appear to be the correct color in the photograph.

Additionally, when the individual pixels are closer together, as they are with a small image sensor, it's possible that the electrical signals that the pixels generate could interfere with each other, causing errors in the measurement of the light.

So while the number of megapixels a camera can record does play a role in image quality, the physical size of the image sensor plays a larger role. For example, the Nikon D810 has 36 megapixels of resolution, but also offers a very large image sensor, so it has the best of both worlds.

Changing the MP Settings

Most digital cameras give you the option of changing the number of megapixels that are recorded in a particular photo.

So if the camera's maximum resolution is 20MP, you may be able to record images that are 12MP, 8MP, 6MP, and 0.3MP. 

While it's generally not recommended to record photos with fewer megapixels, if you want to ensure a digital photo that will require a limited amount of storage space, you'll shoot at a lower megapixel setting, as recording with a larger number of megapixels or at a larger resolution requires more storage space.

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