Focus: Megapixels

Focus: Megapixels

I decided to write this from a question I got from my cousin.  He asked about upgrading cameras.  So I will go over one of the main selling points of a camera that a lot of people base choices on.  Common question is "how many megapixels does it have?"  First off, what is a megapixel? Lets start there.

A megapixel is one million pixels.  Mega is just a prefix for a number and a pixel is a really small square of light that makes up images on a sensor/screen.  So the more pixels you have effectively, the more detail and resolution you should have in your photos.  So if you have a lot of pixels you can have more detail and such.  However, how many is enough?  Using the new iPhone 4 as an example, they have more pixel detail in their screens than our eye can see.  So for example, the screen detail could get more pixels and better resolution but we wouldn't be able to tell.  So there is a limit for our eyes.

So what is a good number of Megapixels (MP)?  I would say between 10-12 MP will be just fine for your average shooter.  However with that said you can get great photos with less than 10 MP.  And if you are lucky enough to be shooting with lets say a D3X with 24.5 MP then I am sure you can get good photos too.  So next I should answer what do these MP's do for you?

Well they let you do two main things from my experience other than make for more or less resolution in your photos.  First, the more resolution you have, the more you can blow up your prints to larger sizes.  Second, the more resolution the photo, the more you can crop it and still have it be a good resolution.  With my D90 at 12.3 MP I believe, I can print out a 2'x3' print of a photo I took with my kit lens(18-105mm).  So I have this photo that is two by three feet framed above my bed:

Haida Gwaii Beach - 18-105mm

It wasn't that large of a file, between 2-3 mb.  So not a lot of detail but the print looks amazing.  So why are there cameras with more than 12 MP?  Well for two reasons I know of.  One, is you can print out even larger photos without even thinking about it looking bad from lack of resolution.  That is why the D3X has 24.5 MP.  You can print off a billboard and not break a sweat with that camera.  Do most people do this? No.  And the other reason is cropping.

Some people don't want to crop images because they think you should keep all your resolution you can.  And also it is usually a compositional issue if you are cropping.  Some believe that composing your image should be done at the time of the shot rather than after.  But if you start with a lot of detail then you will still have hopefully a lot of resolution left after you crop.  So having more MPs let you crop photos more.

So after a point, MP's don't matter a lot if you are not printing 8 foot prints or cropping your photos right down to nothing.  So if you are getting a new camera or upgrading, keep this in mind.  There are many other features to look for rather than megapixels.  

Hope this helps!