The megapixels on a camera hardly matter anymore to the normal user. Megapixels quantify how many pixels make up the photgraph - but since the pixels are all the same size from camera to camera, megapixels do not determine clarity in themselves. Rather, they determine the size of your photograph. If you're viewing on a computer screen, a higher-megapixel photo will be larger. The only time megapixels determine clarity are when you print the picture - since you are fitting the entire photograph onto a 4x6 or whatever - a higher-megapixel image will appear less grainy. Most people only print 4x6 images, and one can hardly notice the difference of anything 4.0-megapixels or higher. Megapixels also come into play when you use the digital zoom feature on your camera, but you should avoid it at all costs, because it diminishes the quality of your photo (I have the feature disabled on my camera.)
I am on my second camera. I own a 5.0-megapixel Casio Exilim, and before that, owned a 3.3-megapixel Vivitar. If I were buying one today, here are the things I would look for - because digital cameras have come so far in the last couple years, megapixels are less important than all of the following:
- Battery. Look for a camera with a Li-Ion rechargeable batter. This will provide you with maximum battery life (my camera is good for about 400 shots w/flash per charge), and will save you a ton of money in the long run. If you buy a cheaper camera that uses AA batteries, you will spend the cost of the camera on batteries before you know it. If you have a camera with a built-in Li-Ion battery, you don't have to carry a spare, and you don't have to charge it as often as you do rechargeable AA batteries.
- Processor speed. Cameras don't really advertise it, but it is the real difference between a great camera and a mediocre one. To find the right one, that means you'll have to go out there and look at a demo model and try it out. How long does it take after you press the shutter button for it to finish capturing and writing the image to memory? The slower the camera is in this respect, the more you'll have problems with poor photos due to an unsteady hand. With my first camera, It took upwards of two seconds for it to record the photo. It is VERY DIFFICULT to hold a camera still enough to get a good shot when it takes that long to record the photo. Also, a faster camera will boot up faster, meaning you miss less spontaneous or candid moments waiting for it to start up. That's really important if you have kids.
- Optical Zoom. Optical zoom is where the camera's lenz physically zooms in on the subject, as opposed to digital zoom, where the camera enlarges the pixels that form the image to make the image appear to be zoomed. Larger pixels means grainier photos, so you'll want optical zoom. I can't really say how much zoom is enough. Most cameras come with 3x - but there are cameras with better zoom out there.
- Size. You want something that's large enough for you to operate effectively, but small enough to carry with ease. If your camera is too big, you're less likely to bother taking it with you and using it than if it were easy to carry.
- Memory card. I don't think format matters all that much, but I'd make sure to get a high speed memory card like the Ultra II cards from SanDisk. It is capable of a faster write speed than their standard memory cards, meaning you can take full advantage of the processing speed of the camera, and will have more success with action photographs.
It probably sounds like I'm giving a sales pitch here. I do sell these things for a living, but I'm speaking mostly from my experience with the two cameras I've owned. I VERY HIGHLY recommend the Casio Exilim line. It excels in all the areas I highlighted, and they have some very affordable cameras right now in the 5.0-megapixel range. I've had mine for just under a year, and it has been nothing short of excellent.
