The Difference In Megapixels

Does It Matter and How Many Are Enough?



We see it all the time in digital photography, the battle to create the next big difference in megapixels, otherwise know as the Pixel Race...

More pixels are better, right?

The more pixels in a file, the more detail can be captured and the better the final photograph?

A 16 megapixel camera is better than a 10 megapixel camera, yes?

Well, in all the above cases, not necessarily.

You see, in digital photography, manufacturers are always having to weigh up a number of physical characteristics in order to make them work together in beautiful harmony.

Two of those characteristics are signal and noise.

To put it simply...the smaller the pixel, the less signal (light) that can travel through it and the more noise prevails in the mix.

The noise element becomes proportionally higher in the ratio of signal to noise and therefore creates a greater (usually less desirable) influence on the final image captured.

So, if there are 16 million pixels crammed into the chip of this year's camera when only 10 million pixels were on the same-sized chip in last year's model, the real-world image quality may not have improved too much!

difference in megapixels, dam wall

In my article "What is a Megapixel?" I alluded to a favourite metaphor when explaining the difference in megapixels and their corresponding chip sizes — that of the dam wall.

I'll hold my hands up now and confess that this metaphor is extremely simplistic, so be prepared!

Hopefully, however, it helps illustrate a point:

As you may know, a dam is used to hold back large quantities of water in a valley.

In withholding water on one side of the wall, there's a whole load of latent energy waiting to be harnessed.

This is achieved by releasing the water via large chutes in the dam wall in which there are mechanisms for the rushing water to drive turbines.

Once spinning at high velocity, the turbines generate electricity.

Now, here's the crux of my metaphor:

If you are the person in charge of building the dam and you have to decide how best to let the water flow through the dam quickly and efficiently, what size holes (chutes) would you choose?

A few big ones or lots of tiny ones?

Not sure...?

Well, let me tell you that a few big holes are much better than loads of tiny ones!

Why?

With large diameter chutes, resistance between the flowing water and the walls of the chutes is kept low.

This means that water can pass through the dam quickly and efficiently.

If lots of tiny chutes are used, the ratio of resistance to flow would be high and the water would escape much less efficiently... 






Now Substitute Water for Light!

For the metaphor to be complete, simply substitute water for light!

Larger pixels will generally yield a higher quality capture as light has been able to flow freely through them without being dominated by noise.

Smaller pixels tend to produce noisier images.

In short, if image quality is to improve with the an increase in pixels then
the chip needs to increase in size too.

For a while the difference in megapixels between successive models seemed very important.

Particularly in the higher-end compact cameras and D-SLRs, the pixel race prevailed and manufacturers tried to cram more and more pixels into small chips.

The chips stayed the same size. So, if the quantity of pixels increased, this meant that they (the pixels) needed to be smaller.

More cameras would be sold under the illusion that 'more pixels are better' but the consumer soon became wise to the fact that image quality wasn't improving.

For me, the first clear cut example of a manufacturer acting on this came with the launch of the Canon Powershot G11 in 2009.

Canon actually reduced the pixel count of the camera by 4.7 megapixels from that of its predecessor, the G10.

A bold move indeed but a correct one, in my opinion...

Canon Powershot G10 and Canon Powershot G11


How Many Pixels Are Enough?

Interestingly, over the last few years many accessibly-priced cameras have remained at the 10-12 megapixel mark.

My quick and easy answer is that a pixel-count in this range is enough for most purposes.

I successfully produce beautiful A2 prints from my 12.1 megapixel Panasonic Lumix GF1 for example.

I love this camera and along with others, such as the Olympus Pen range, a new generation of high quality equipment has been created and taken the photographic community by storm in recent times.

Fujifilm Finepix X100

At the time of writing, one of the most desirable cameras around surely has to be the 12.3 megapixel Fujifilm Finepix X100 ...a true return to beautiful, traditional styling with great image quality to boot.

This camera utilises the APS-C chip, which is larger than the Micro Four Thirds sensor in my Lumix GF1 but contains a nearly identical quantity of pixels.

You guessed it! This means that the pixels are larger and should therefore provide a higher quality capture...


So Why Would I Need More Pixels?

You might be thinking that 12 megapixels doesn't sound like too much when the difference in megapixels from cameras further up the scale can be so much higher.

For example, an 80 megapixel camera is now available from Phase One! 

So why would you need more?

Here are three reasons that spring to mind:

1) Cropping

If you need to heavily crop your images, more pixels are certainly an advantage so as to ensure the highest possible quality after you have made your crop.

This is particularly advantageous in a professional scenario where a photograph may need to appear at high resolution in a number of different crops and formats, for example.

2) Large Format Printing

More pixels are also an advantage when it comes to making large prints; a high quality chip with a large number of good-sized pixels will produce better quality large format prints than a camera carrying a more meagre specification.

3) Overall Image Quality

Of course, let's not forget the overall image quality!

More high quality pixels will provide a higher resolution and higher quality digital photograph.

You'll be getting the hang of this now, though...

...the larger difference in megapixels will only improve the image quality if the pixels aren't too small.

Furthermore, the resolution of the final image can only be completely realised if the lens is up to it too!

So many variables to consider...

Hasselblad H4D 31


In Conclusion...

In considering the difference in megapixels, I hope you have found this article helpful.

Really, there are no hard and fast rules with regard to "how many pixels are enough". You will need to make a judgement based on your own needs.

This review site will help greatly in the decision-making process.

However, ultimately bear in mind when making your choice that more pixels aren't necessarily better.

If you do plump for a high megapixel specification, just make sure that a large chip is housing all those pixels!

Unfortunately, you will likely find that a large bank balance needs to house them too...!




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