Pixels are the fundamental building blocks of digital photography: they are the individual elements that capture the light to make up your image. Higher pixel-count cameras promise better resolution but it's often said that their smaller pixels result in noisier, less-clean images.

So does this mean you should look for fewer, bigger pixels when you buy your next camera?

Probably not. That's because the idea that small pixels are noisier is only really true when you examine your images at pixel level. We've long passed the point where you only had enough pixels to fill your monitor. And even people making large prints will find that a 24MP camera provides far more resolution than needed for printing at A3 (11.7 x 16.3").

Looking at the bigger picture

At which point, taking a more holistic, whole-image-level perspective on picture quality probably makes at least as much sense as worrying about the noisiness of your individual pixels.

Smaller pixels each receive less light than large ones, so will always individually be noisier (because for most photography, most of the noise comes from the amount of light you sample). But as soon as we have to scale our images to view or print them, this difference becomes much less significant or disappears entirely.

Key takeaways:

  • Larger pixels get more light during any given exposure, so are less noisy when viewed 1:1
  • Combining multiple small pixels cancels out most (or all) of this difference when viewed at the same size
  • For most applications you'll end up downsizing your images, so there's usually a resolution advantage but little (if any) downside to having more pixels

The effect of pixel size:

The Nikon D850 and the Sony a7S are both relatively modern full frame sensors, but they have very different pixel counts. Because they have the same sized sensor, this means the individual pixels on the 12MP a7S are much larger than the D850, which has a sensor made up of 48 million pixels.

The a7S is often described as being great in low light, but this is only true if you pixel peep.

Let's see how they compare when scaled to the same size:

ISO 6400
D850 Full size
[Raw File]
a7S
[Raw File]
D850 (resized: 12MP)
[Raw File]
ISO 12800
D850 Full size
[Raw File]
a7S
[Raw File]
D850 (resized: 12MP)
[Raw File]
ISO 25600
D850 Full size
[Raw File]
a7S
[Raw File]
D850 (resized: 12MP)
[Raw File]
ISO 51200
D850 Full size
[Raw File]
a7S
[Raw File]
D850 (resized: 12MP)
[Raw File]

At the pixel level the a7S is much less noisy, as you'd expect with its larger pixels. But, at all but the very highest ISO settings, that advantage disappears when you compare them both at the same scale. The difference is that you usually retain some of the additional detail that the D850 captured.

We see this same pattern across almost all cameras. The only times we have seen any disadvantage to small pixels is in the very smallest pixels used in smartphones (and those often use multi-shot modes to overcome this) or in sensors that use unconventional sensor technologies.

The thing that's much more likely to make a difference to your image quality is sensor size. We'll look at this in the next part of this article series...

Click here to read Part 2:
Is a bigger sensor better?