Trying to Define Megapixels?

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Let me help you out: I'm going to define megapixels in a way that should clear up a lot of confusion.

Since the very first digital camera, this one term has been shrouded in mystery. It has been the defining feature on digital cameras for years and has been built up and hyped to no end.

The megapixel race has boiled down to a catch phrase: "more is better".

It makes sense why camera makers and retailers aren't falling over themselves to clearly define megapixels to consumers: a megapixel number makes it easy to compare two different cameras.

"Our camera has 10 megapixels while our competitor's only has 8. I'm sure you can tell which one is better."

And - surprise, surprise - the more megapixels a camera has, the more it costs. Of course a salesperson is going to tell you that a camera with more megapixels is going to take better photos.

But what are these megapixels really good for? In the following paragraphs, you'll find out.

In The Beginning

The foundation of megapixels is the lowly pixel.

A pixel is one dot of information in a digital photograph. Digital photos today are made up of millions of tiny dots (Mega = Million).

This means that a 10 megapixel image contains approximately 10 million pixels, while a 14 megapixel image contains 14 million pixels.

Since a photo has a rectangular shape, the dimensions of one side aren't equal to the other. If we assume that we're looking at photo in landscape orientation:

• A 10 megapixel photo measures 3888 pixels wide by 2592 pixels high
• A 14.5 megapixel photo measures 4672 pixels wide by 3104 pixels high

If you take the width and multiply it by the height, you get the total number of pixels that make up the digital image:

• 3888 x 2592 = 10,077,696 pixels = 10 megapixels
• 4672 x 3104 = 14,501,888 pixels = 14.5 megapixels

This is just the tip of the iceberg - there's a lot more information required to define megapixels.

Is More Better?

So a camera with more megapixels takes clearer photos right?

After all, if one camera is capturing 14 million pixels and another is only getting 10, then the photo with 14 million pixels should look better.

Not exactly.

While a digital photo that contains 14 million pixels is physically larger than one with only 10 million, when viewed and printed at small sizes they are hard to tell apart.

Can you tell which of these two photos has 10 megapixels and which one has 14?

The real notable difference is not one of quality, but one of file size: 14 megapixel cameras create larger digital files than their 10 megapixel counterparts.

A larger file size means:

• You need to purchase higher capacity memory cards (4GB or more)
• It takes longer to transfer an image from the memory card to your computer
• You need more hard drive space on your computer to store your photos
• You need a more powerful computer to organize and edit your images
• You must dramatically reduce the size of photos to send via e-mail
• It takes longer to upload the original images to an online gallery

This leads us to ask an important question: what's the point of cameras with more megapixels if image processing takes up so much time and space?

Large Print Sizes

First, the most obvious advantage:

You can print photos with more megapixels at large sizes.

Let me define this another way: if you print an 10 megapixel photo and a 14 megapixel photo at 4x6 inches (standard print size) you'll be hard-pressed to tell which one is which (just like when you compared the small images above).

But if you print both photos at 20x30, then you will see a difference in quality.

The 10 megapixel photo won't look as clear and as sharp as the 14 megapixel photo when printed at this large size.

This table shows the most common "acceptable" print sizes based on the number of megapixels.

Here's how to read the megapixel print size table:

• With a 10 megapixel camera, any print that you make that is 12x16 or smaller will look fantastic
• With a 6 megapixel camera, you can make high-quality prints at 9x12 or smaller

Can you print your photos larger than the acceptable size? You bet.

There's nothing stopping you from printing your 6 megapixel photos at 20x30, or even billboard size if you so desire.

But there is a catch: as you increase the size of a print above the acceptable print size, the image quality deteriorates.

A 4 megapixel photo printed at 4x6 will be perfectly clear. It will also be clear at 8x10. But a 4 megapixel photo printed at 11x14 will show a loss of image quality. The same image printed at 20x30 will show considerable loss of image quality.

BOTTOM LINE: If your goal in life is to make really large prints, then compare cameras with lots of megapixels. If you just want to print at 4x6 and e-mail photos to friends, then spending a lot on more megapixels is a bit of a waste.

More Image Cropping Options

You can now define megapixels in one way: more of them lets you make larger prints.

There is a second benefit to having a lot of megapixels in your photos: it gives you freedom to crop.

Let's say that you've taken a photo with an 8 megapixel camera - you're able to make nice 12x16 prints with this.

On a photo safari, you take a photo of an egret, but you're too far away from the bird and you don't have a telephoto lens to get up close and personal.

The primary subject of your photo is tiny. You decide to crop the shot so that the egret appears larger.

No problem...except that you can no longer print at 8x10.

You need 8 megapixels to print at 12x16 before the image starts to deteriorate. When you crop the image, you are eliminating pixels - let's say that you crop out 2 megapixels from your photo.

You wind up with a 6 megapixel photo - you can make a nice 11x14 print, but that's about it.

Now imagine that you take the same shot with a 10 megapixel camera.

With this shot, you can crop out a full 50% of the image (5 megapixels) and still make a high-quality 9x12 inch print.

But be aware that cropping and adjusting your photos takes time. In fact, it takes a lot longer to edit photos than to take them in the first place.

BOTTOM LINE: If you don't want to spend your time sitting in front of the computer editing and cropping your photos, then a camera with tons of megapixels doesn't provide you with an advantage.

Buying Tip

Let's conclude our introduction to megapixels with a quick summary of some of the reasons for and against getting a camera with more megapixels.

Get a camera with a high megapixel count if you:

• Want to make very large prints of your digital images
• Want to crop out large portions of your photos and still make large prints

Don't spend all your hard-earned money on lots of megapixels if:

• You rarely make prints larger than 4x6 inches
• You just want to upload images to an online gallery
• You enjoy sharing photos with friends via e-mail

There you have it: the mystery of megapixels has been clarified. That wasn't so hard, was it?

Now that you know what they're about, get out there and define megapixels for others so they don't have to stay in the dark!

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