Bigger sensors makes sense – usually

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We checkout one reason why a bigger sensor is better and one reason why it isn’t.

I have a collection of cameras, each having specific benefits. Included in the collection are a 4/3 (Four-Thirds camera) used for more ‘serious’ photos, and a ‘superzoom’ bridge camera (for when I am not intending to take photos, but ‘you never know’, so I need something light to carry).

The 4/3 has a much richer range of functionality, but the superzoom has lightness on its side and a massive x50 zoom lens but with a crop size of 5.6. The 4/3 has a crop size of 1.6. You can read all about crop sizes (see in our other article here, but basically the smaller the crop size the bigger the camera’s sensor.

The 1/2.3″ sensor is about 29mm2, and the 4.3 has a sensor of about 225mm2. This is a big difference, but basically the superzoom could not offer the massive 50x optical zoom without using a very small sensor (or large and very expensive optics). A large sensor can capture much more light which is particularly useful at higher ISO ranges. What is ISO?

So, there are trade-offs.

I wanted to highlight the difference in performance at higher ISOs, so I took the same photo with both cameras at various ISOs. See the chart below

This is the image I took on both cameras (and then sampled the middle of the frame):

ISO 4/3 sensor at about 70mm zoom superzoom at about 24mm zoom
3200 not available
6400 not available

At ISO 100, both sensors are fine. You would expect the 4/3 to be “much better” but in fact the superzoom was really good at ISO 100. However, this blog is not supposed to be a comparison between the cameras because it’s not an equal test; to capture the same angle of view I had to use very different focal lengths hence the difference in depth of fields. This blog is to compare the difference in performance of each sensor when using different ISOs.

The superzoom allows ISOs all the way up to 6400 (and 12800 actually) but frankly I would not like to use the zuperzoom above ISO 800 – which is sad because its range of available apertures is very limited so flexibility is needed. Actually it’s ironic that the superzoom offers a higher range – but less usable – of ISOs. They would be better-off not having it but I suppose the marketing folk got involved and insisted…

The 4/3 – because it has the bigger sensor, is more consistent up to ISO 800. ISO 1600 (its fastest ISO setting) is still very usable in my humble opinion.

Horses for courses

For varying light conditions where image consistency across ISO settings is useful, the bigger sensor is better.

See Amazon UK’s DSLR cameras and their Compact System Cameras

And the purist will probably shudder when they see a superzoom being used. But in actual usage, the longer zoom reach of the zuperzoom has on occasion allowed me to capture images that I could not with other cameras, and that’s its great plus. However, the superzoom needs good light and ideally used at ISO 100 or 200 which is not always possible.

The superzoom can easily reach 800mm zoom equivalent in 35mm terms, and and a quick look says that a 800mm full frame lens might cost you £6,500 and weigh in 6.8KG. The optical quality of the superzoom will be nothing by comparison obviously. But that’s not the point; this point is that I can actually afford a superzoom and have used it when I couldn’t otherwise get the shot. And it has image stability – which is essential to cope with this camera’s range.


For me, it’s no surprise that a bigger sensor is better for a wider range of light conditions. And assuming I have the lens to reach, a bigger sensor wins without question. And as an enthusiast with over 40 years of photographic experience, the DSLR is my “go to”. Purists – you can breath again…

But just once in a while the superzoom makes an appearance to save the day, and you should see my stunning long-distance meerkat photo (ISO 100, F5.9 1/100s with a 450mm in 35mm terms, whilst leaning on a rock). I’ll take a tiny sensor any day of the week not to miss that shot.

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