NidalM Photography / Blog / Better Photography / How Many Megapixels is That?

How Many Megapixels is That?

Posted by NidalM on Oct 20th, 2009 | 19 comments

It’s the biggest scam of the camera world. One that has been propagated through extensive marketing and consumer ignorance. And one that irks me to no end. I recently bought a Canon 5D Mark II, and the first thing anyone who sees it asks: “How many megapixels it that?”. My answer of “21″ causes much eye popping glee and a “Wow, that must be a good camera” as I inwardly roll my eyes.

Don’t get me wrong! I wholeheartedly agree. The Mark II is a great camera. But not because of its megapixel count. In fact, a lot of you might be surprised to hear that even though the Mark II supports up to 21MP, I usually set the output mode to sRAW which is just 10MP. Recoiling in horror yet? Read on.

It’s All About the Buckets

Let me start off with an analogy. There was a time when a computer’s clock speed was all the rage. Manufacturers kept touting higher and higher gigahertz. But we all learned to look beyond that. A new laptop might have an insanely high processor speed, but if its RAM or bus (the circuit that connects processor to everything else) is slow, it will just keep the computer from high performance. Similarly, if a car has tricked out horsepower rating but a suspension that causes the thing to shake at high speeds, then you can’t really go that fast with it *cough* American cars *cough*.

In the same vein, while Megapixels are just one metric for gauging a camera’s performance, simply pumping up pixel counts does not necessarily mean a better camera. In fact, in some cases, it makes for a worse camera.

For simplicity, we’ll use an analogy. Lets think of a camera’s image sensor as an array of buckets. When the shutter opens, light comes in, it falls into the buckets, and the camera then counts the different colors in each of the buckets to produce an image. As you might have already guessed, each bucket represents a pixel. A 10MP camera would have 10 million of these buckets, all condensed into an area the size of a letter key on your keyboard.

A very simplistic representation of camera image sensors. In reality, each 'bucket' would capture just one color of light and special algorithms are used to de-mosaic the image.

Because of the escalating megapixel war, manufacturers have been cramming more and more of these buckets into the same sensor size (because image sensors are expensive). This means smaller buckets and hence smaller areas to capture light. Of course, these light detectors in the buckets are not perfect. That is because they are converting an analog signal (light intensity) to a digital signal (a pixel, defined by 16 bits of color). Sometimes they will mis-count the amount of the different colors of light.

In big buckets this is not a problem, because even if the camera counts one more or one less, the mistake is relatively small. For example, a bucket has 10 red balls and the camera counts only 9. Big deal, only a 10% error. On the other hand, smaller buckets capture less light, and hence are more error prone. A bucket with 2 red balls counted as 3 means a 50% error! This results in noise. It’s the annoying dots that appear in your images making everything look grainy.

An image with extensive noise.

Simply put, increasing the number of Megapixels on your camera, without advances in noise reduction technology, increases the noise on your pictures, reducing image quality. In fact, industry experts say that a point & shoot camera gains little performance beyond 6-8MP. For SLRs, since they have a larger sensors, the limit is somewhere in the 30-40MP range.

The Megapixel Race is Over

And it ended sometime early this decade. But it happened very quietly. In fact, some camera marketers don’t seem to know this either. They still want you to believe that gazillion megapixel camera is what you should buy. The truth of the matter, however, is that unless you want to make (insanely) large prints of your images, you don’t gain much beyond 12MP.

Keep running the Megapixel race and you'll get THIS 160 Megapixel baby. Yes, its that huge because you need a massive sensor to handle all those pixels with low noise.

Make smarter decisions when buying your next camera. Drop the megapixel hype and concentrate on what really matters. Look for the image quality. Look for noise performance. Wider angled. Zooms (optical). Sensor size. Shutter lag. Image stabilization.

Not a rocket scientist? No problem! Check out DPReview! Or drop me something in my inbox.

Tags: buying guide, megapixels, photoschool

No related posts found

Liked this post? Subscribe to my RSS Feed or add me on Twitter for updates.
Or share it with your friends!

abdelhamiddrira

thanks for the explanation
how much does this camera cost, sorry not to be rude just that i am interested like i told you before .
also is Canon the best company what about Nikon or Sony
http://www.nidalm.com/blog/ NidalM

Well, I recommend checking Amazon for the latest prices. It's an expensive camera to say the least.. and a very sizable investment.

I get the question about Canon vs Nikon vs Sony a lot. The short answer is, none of them is better than the other. They all have their pros and cons.
http://nsahmed.wordpress.com/ Nabeel

Abdullah, did you ever read David Pogue's classic series on the Megapixel Myth a few years ago?
abdelhamid

i checked on ebay 2400 dollars , something like that
that s an investment for sure .
anyway i am tempted to buy it, if my wife does not kill me, lol .
http://www.waleedsgallery.biz/ Waleed Alzuhair

Good article..
If I may comment on RAW vs sRAW, this will NOT increase the size of the pixel (bucket) and it will only reduce the size of the file. The benefit of capturing more data in a larger pixel, contributes to the increase in dynamic range and reduction in noise. If you compare the generated RAW and sRAW, you'll notice that both are the same since both came from the same sensor.

Storage media is now more affordable than ever, my vote goes to RAW instead of sRAW.
http://www.nidalm.com/blog/ NidalM

I didn't, actually. The Megapixel myth has been known in the industry for some time now. But for some reason, it hasn't trickled down as well to the common consumer…
http://www.nidalm.com/blog/ NidalM

I completely agree. using a larger number of buckets to render a smaller number of pixels will result in better noise performance (in theory). But you're right. RAW definitely is superior since sRAW demosaics the image in the camera and hence is not a true RAW image.

I like sRAW mostly for the fact that it improves burst performance on the camera and the fact that most in most PR shoots clients won't need large prints of their images.
Chiara

I'm just testing if the commenting jinn still hates me
Chiara

Hah!!!! For you I have to use Firefox Mozilla or whatever it is–fussy you are!
Chiara

That “160 Megapixel baby” looks like a back to the future camera–heading towards being as big as the original box camera.
phoeb

So…what about the integrated cameras in cellphones? What maximum resolution would you suggest for a satisfactorily clear image? 8mp seemed noiseier than 5mp on nokia. Maybe something to do with the screen?
http://www.nidalm.com/blog/ NidalM

As you might imagine, cellphone cameras currently use the smallest image sensors of all cameras. As a result, a 5MP cellphone will produce a much noisier image than a 5MP point-n-shoot. Theres many reasons for this, not just the sensor size. The flash is terrible for night shots and many phones use fixed optics (no autofocus) which is never optimum for all shots.

Cellphone cameras are improving steadily but I really wouldn't recommend them for any form of low light photography. For well lit shots which which are going to end up on facebook, a cellphone can't be beat, simply because you have one everywhere you go.

Since sensor sizes and technology vary a lot over cell manufacturers, I'd recommend reading up reviews for specific cellphones before going out to buy them if image quality will make a major factor in your buying decision.
Oz

I always aim for Carl Zeiss . I hope that's good enough? Heck, I bought my N82 because of this!
Mouazam

I don't even know you, but it's good to see someone who is aware of this. I wrote a similar article once.
Mouazam

Hi Nidal,

Regarding the Canon vs Nikon debate, based on this megapixel thing it's fair to say that CURRENTLY nikon has the advantage in bodies. The reason for this is exactly what this article you wrote is discussing, nikon's full frame sensor say for the D700 has 12 MP so each pixel is bigger. Because of this that sensor has more dynamic range and a lot better high ISO performance compared to the canon equivalent, the 5d mark ii. Furthermore, the AF on the D700 is far far more accurate than the 5d mark ii. I had a 5d mark ii as well. It seems as canon is concentrating more on marketing for their bodies vs image quality, so they keep increasing pixel density by raising MP thus compromising high iso performance. What canon needs is a Full frame sensor with a low MP count, this will allow for better noise performance and faster fps since the processor has to process less data.

If someone is starting from scratch, currently Nikon has the better bodies by quite some margin, so I usually suggest those. But I am certain in the future, canon will come out with a FF and stop this MP race… there are a lot of rumors of a 3d, a FF low MP camera with a Pro AF.
http://www.rys-raziel.blogpsot.com/ Ren_crow

I always was amused by the whole obsession with megapixels. And btw not everybody who asks about megapixels on a new camera is a megapixel fanatic, it is after all part of a camera's specs.

I'd like to see myself wearing that 160 Mp camera hanging around my neck.
Danish Shah

This is why i bought a Nikon D700 with 12.1MP sensor its rated one of the best noise performers
http://texaninuae.blogspot.com/ Texan In UAE

I found this out a couple months back. I was always the one that was asking. LOL Thanks for the nice informative article.