So what the heck is an “Effective Megapixel”?
If you think it’s a marketing gimmick, it is, but not in the negative sense that one would expect.
Actually it’s a positive thing for which all digital camera manufacturers and marketers should be congratulated.
An “effective megapixel” is the actual number of pixels which make up the viewable image captured by a digital camera.
If for example a camera has 4.5 megapixels with 4.1 effective megapixels you can safely ignore the 4.5 part. 4.1 megapixels is what you’ll actually see in a photograph.
The difference between these two concepts is expressed beautifully by this food analogy published by digicamguides.com:
Total Megapixels: This is like the full plate of food.
Effective Megapixels: This is the amount that you eat.
And did you know that the number pixels is important only with relation to the ultimate PRINT SIZE?
That is, a 2.0 megapixel camera produces pictures as sharp as an 8.0 megapixel camera if you never print anything larger than 4” x 6”, which is the standard print size in the USA.
So, if you’ll never print anything larger than 8” x 10”, you’ll never need a camera with more than 4.0 megapixels.
But the camera manufacturers of course will never tell you that in order to keep selling more expensive cameras with even more megapixels. I don’t believe the human eye can even tell the difference beyond 4.0 megapixels.
Here is a Print Chart to help you decide what kind of a camera you might need:
Megapixels — Print Size (inches)
2.0 — 4 x 6 [standard]
3.0 — 5 x 7
4.0 — 8 x 10
5.0 — 9 x 12
6.0 — 11 x 14
8.0 — 12 x 16