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Scott M

The Megapixel myth and consumer shopping

2 posts in this topic

Don’t start search for digital camera before resolving Megapixel Myth

By RUSS JUSKALIAN, New York Times

It happens to all of us: the moment when one finds out that more megapixels and better photographs aren't always the same thing. To be disabused of the Megapixel Myth -- this decade's analog of the Megahertz Myth -- can lead to an existential buyer's crisis in miniature.

Disbelief, at first, gives way to a sort of embarrassing self-questioning: You mean, 15 megapixels isn't three times better than 5 megapixels? This year's model isn't better than last year's? I spent all that money upgrading -- for nothing?

The panicky consumer is then faced with the choice of dumping digital electronics or learning about camera technology and taking control of purchasing decisions.

Upon pursuing this latter path, one soon realizes that all is not lost. Newer generations of digital cameras and camcorders, which almost always have more megapixels or higher resolutions, still tend to produce great output.

But there is more to a digital camera's sensor than resolution. Understanding some of the basics may just convince you that, at least this year, buying last year's model is a smart move.

In a sea of specifications, one of the most overlooked is the size, not the number, of pixels on a camera's sensor. Bigger sensors usually mean bigger pixels, which provides some advantages when it comes to making an image.

The mechanics of this can be understood by thinking of a digital camera sensor as a flat sheet of material pocked with millions (hence "mega") of cylindrical, cuplike pixels. In other words, picture the digital sensor as a tiny cupcake tin.

Photons (light particles) pass through a camera's lens and are captured by the cups in the tray. Each cup is either red, yellow or blue (the three colors that are the building blocks for all other colors). The more photons a cup catches, the brighter that cup's color. Totally empty cups record black; totally full cups record white.

Often not worth paying extra

Larger pixels (cups, remember), with larger surface areas, capture more photons per second, which in electronics-speak means a stronger signal -- and in camera-speak means less noise and cleaner colors. Bigger pixels can also capture more photons per exposure without filling up, so larger pixels hold on to their color longer and don't go white as quickly as smaller pixels.

Since sensor sizes in compact cameras haven't gotten much bigger, but their megapixel count has, increasing the number of pixels can be accomplished only by using smaller pixels. For this reason, it's often not worth paying extra for the newest megapixel champion, says Phil Askey, editor of dpreview.com.

"Once you get beyond seven or eight megapixels in a compact point-and-shoot camera, the small lenses are struggling to keep up," Askey said.

The same thing is true for digital single-lens reflex cameras. In fact, recent tests conducted at dpreview.com concluded that the new 15-megapixel Canon EOS 50D ($1,400) "shows visibly more chroma and luminance noise," and slightly less dynamic range, than the older 10-megapixel Canon EOS 40D ($920).

As a way to visualize just how densely packed sensors have become, Askey's HSOforum provides pixel density and sensor-size data on more than 1,200 digital cameras.

So if you're in the market for a "pro-sumer" DSLR (a consumer camera with the quality and features of a professional model) that minimizes noise issues, take a look at the Canon Rebel XSi ($600), Canon 40D ($920), Nikon D80 ($640), and Nikon D90 ($1,000).

Tapping your inner pro

Another advantage of a larger sensor is the ability to produce images where only a relatively small portion of the subject is in focus. Understanding how this works may require a physics degree, but in general, cameras with small sensors tend to produce images where almost everything appears to be in focus.

This is the main reason that, in normal shooting situations, images produced by small point-and-shoot cameras and DSLRs look so distinct. In digital video, the result of using small sensors is sometimes referred to as the "video look."

The bad news: You'll probably need to use a DSLR to produce a really shallow depth of field. The good news: You can achieve that professional look with the cheapest of entry-level DSLRs, which are also relatively small.

If you're looking for a smallish camera that can achieve shallow-depth-of-field images, good deals include the Canon Rebel XS (around $510 with lens), Nikon D40/D40X (around $450 with lens), and Olympus E-420 (around $460 with lens).

Though some experts say they believe that improvement has slowed in digital imaging, it's always wise to remember that with technology, today's rules are tomorrow's anachronisms.

But no matter when the next advance in digital imaging comes, the old saying that the photographer is the most important part of a good photo will still hold true.

Consider Alex Majoli, an award-winning Magnum photographer known for shooting images of war and other dramatic scenes for publications like National Geographic -- with compact point-and-shoot digital cameras.

Or consider the more critical words of Ansel Adams, who once wrote, "The sheer ease with which we can produce a superficial image often leads to creative disaster."

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Something my parents, friends, and sister need to see, and that's coming from a guy who knows the bare minimum about cameras!

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Good article, Scott. Thanks for posting it. smilesmile

I've largely resisted the compulsion to upgrade every year, not to mention the financial angle. The megapixel war is a battle of marketing, not need, the targeting of the perception that more is better.

I'm still using 8 Mp DSLR bodies, and while I may upgrade one of those bodies to a 15 Mp body, it's not because of the megapixels, but because of the other features.

In image quality comparisons between the 40D and 50D, it's important to note whether in-camera noise reduction was used in the 50D for the comparison. Side-by-side with the 40D, the 50D will show more noise, but when the in-camera 50D noise reduction is enabled at the "strong" level, that's when the camera shines. Since this article is trying to make the point that newer cameras and more megapixels are not necessarily better, it may be that the comparison does not allow the 50D's noise reduction in the mix, which is like comparing a new turbocharged mustang to the last model of non-turbo mustang but leaving the turbocharger off in the new one. The DP Review assessment has been one of those that has not allowed the in-camera noise reduction in the 50D when comparing noise/IQ on the two bodies. Sure, you can compare them that way, but why do it? It's not a real-world comparison.

Ideally, I'd love to see a 50D with 10-12 Mp and all its new technology. That would be a total assassin when it comes to noise and image quality. I shoot my 1.6 crop 8 Mp sensors at iso1600 freely and at need, and have had great luck and little noise with that when the images are properly exposed. I've made prints now to 30x45 with those 8 Mp 1.6 crop sensors, and the images are great. Imagine the new technology at 10-12 Mp on that crop sensor instead of 15 Mp. But of course that won't happen because it's all a battle of marketing overcoming real-world need.

One of the basic theses of this article -- that it's the eye, mind and heart behind the camera rather than the Mp count within it that dictates artful photography -- is so true and so important that it bears repeating as often as anyone cares to repeat it.

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