Tip of the Day - Megapixels

As the race to cram more pixels into smaller and smaller cameras continues, it might be worth while to slow down a bit and look at what all those pixels actually mean. In fact, it may be useful to ask "What is a pixel?" and "What's so 'mega' about t it?"

The word pixel is variously described as a contraction of picture element or picture cell. The basic idea is that a pixel is the smallest unit of an image on a computer screen or a computer printed page. It's basically the smallest dot that makes up a dot picture. The smaller the dots (and the more variation in the way those dots can be displayed), the more detailed the image can be.

The image above is displayed with LARGE pixels-- too large, in fact, for the image to be readily recognizable. Below is the same image with "standard" pixel size.


"Mega" in the case of megapixels is just a term of measurement. One megapixel is simply one million pixels. Thus, a 6 megapixel camera crams 6,000,000 pixels into the sensor. (Phew!)

I think almost everyone reading this know about pixels, but it's good to cover the basics.

The more important, or more-often-asked, question is: how many megapixels do I need in the digital camera I'm going to buy? The answer to that question, like so many others in photography (and in life, really) is: "It depends."

The main factors that help determine how many megapixels you might need are:

1. What kinds of enlargements do you plan to print? (the larger you plan to print, the more megapixels you'll want to have to work with)
   
2. How much cropping do you plan to do? (cropping your photographs from full frame down to 1/2 or 1/4 frame may result in degraded images if you start with too few pixels. More pixels in the full frame means more pixels in the cropped frame)
   
3. Does the camera, independent of megapixel count, have the features and quality I want/need? (you'll want to consider, among other things, the camera's lenses (are they quality glass or cheap plastic?), sensor quality (newer sensor generally perform better than 1st or 2nd generation sensors), available modes (see the previous Tip of the Day), responsiveness, and price when buying)

There's no easy answer to "how many pixels is enough?" but most contemporary cameras (meaning those being sold new today -- Sept 2008) are very, very good and will yield exceptionally satisfying results. Even lower end cameras have 6-8 megapixel counts and 3rd or 4th or 5th generation sensors.

Now is a great time to buy a digital camera.