You find yourself in the midst of choosing a new camera and you are being bombarded with information about all sorts of features and accessories for the various cameras. How many buyers decide on their ‘choice-camera’ is by the amount of megapixels it has. (or MP for short)

While this is by far not the only feature you should be taking into consideration, it is an important one and it does help to have a better understanding of the how and why.

You do need to know that a point and shoot 10MP camera is VERY different to a 10MP DSLR due to the other factors involved (like your sensor size) but I am not going to get into that right now - right now I just want you to understand how megapixels affects your photograph.

Firstly, what are megapixels?

When you take a photograph, the image that you see is made up of thousands of tiny dots. These tiny dots, arranged in specific patterns, make up your complete image. These tiny dots are each called a Pixel.

When you put exactly one million of these pixels together you get a Megapixel.

Megapixels are abbreviated to MP. So you if see a picture or file size that is 6MP large – you know that file is made up of 6,000,000 pixels.

Here is how this works.

In the menu of your DSLR you will have the option to change the size and quality that you want to save your images in. for example on a Canon 400D:
A Large or high quality image setting is 3888 x 2592
A Small or low quality image setting is 1936 x 1288

What this means is that for the large quality files the width of you image holds (per row) 3888 pixels and the height (per row) holds 2592 pixels. So 3888 x 2592 = 10,077,696.
Therefore your large quality image will be roughly 10 megapixels in size. (the size of your image also depends on your settings when you take the photo:  lighting / ISO etc) but that gives you an idea of where you will be in the size department.

So lets say, to explain further, that you have a picture that is 1600pixels by 900pixels and the quality is good (lets says 1.2MB) and you have that same picture at a much lower quality (lets say 70KB - kilobytes are a smaller way of measuring pixels)

If you zoom into the 1.2MB image and the 70KB image you are going to see a very big difference in quality. While the width and length are the same for both image – the bigger file has comfortably fit 1,200,000 pixels into the space given – the smaller file has only fit 70,000 pixels in it. What happens in the smaller image is that the pixels will stretch themselves to fill in the space that needs to be filled in and the picture will become ‘pixelated’ meaning that instead of seeing a smooth picture you will actually be able to see the pixels that are making up the image.

pixels1

The same image filling the same width and height will look very different depending on how many pixels make it up. The image on the left has many more pixels that the image on the right where the fewer pixels had to stretch themselves to fill up the space given and therefore the finer detail in the image is lost.

So then of course the difference between a 10MB image and a 20MB image of the same height and width is that the 10MB image has had to stretch it’s pixels to twice the size of the 20MB image in order to fill in the same amount of space.  This also means that the 20MB image will be able to be printed double the size of the 10MB image and have the same result in quality.

To touch on how the sensor size is the actual deciding factor on quality:
If you have a sensor that is 1cm by 1.5cm in size and you cram 10million pixels onto that sensor & then you have another sensor that is 2cm by 2.5cm and you cram 10million pixels onto that sensor > the space between the pixels on the bigger sensor will be bigger.
The closer the pixels are to each other on your sensor the more electronic interference you are going to have between pixels. This interference creates a lower image quality!

So those little point and shoots that boast 14MP….just check how big their sensors are before you rave about that!

Two point and shoots, both with the same size sensor: one with 10MP and one with 14MP > The 10MP one is most likely going to produce better quality prints!*
Remember to take in all the pros and cons about the camera before deciding which to buy.
To find out the sensor size and compare cameras to each other before knowing which is better to buy: visit this site