Digital Camera Pixel Density

Pixel density. That’s a term many are not familiar with. Pixel density is the number of pixels divided by the display or imaging area. This blog post will be about digital cameras, so pixel density refers to how big or small the image sensor pixels are. And to get to the bottom line quickly: generally speaking, bigger image sensor pixels are better.

Digital Camera Sensor
Image courtesy: PhotoAxe.com

Aren’t more megapixels better? Not necessarily. We are dealing with light and to capture more light you need bigger lenses and bigger sensors or both. Of course with advances in sensor technology we can make the sensors more sensitive to light. With light sensitivity made equal among sensors, the bigger sensor is able to capture more light. And more light means better pictures. So what does this have to do with megapixels? Given the same image sensor size and sensitivity, if you cram more megapixels into it, each image sensor pixel will be getting less light. Less light means poorer images.

Digital Photography Review (DPReview) is now adding pixel density information to its database of digital cameras. This is good news since pixel density can be a powerful gauge to ascertaining picture taking ability.

Here is the entire announcement by DPReview:

We’ve added some new information to our product database to make it easier to understand the characteristics of camera sensors. The idea of megapixels is generally well understood but, mainly because of the way they’ve historically been presented, sensor sizes aren’t.

We feel that relating these two pieces of information gives a clearer understanding of how they interact. To achieve this, we’ve added the new field: “Pixel Density” to our database, to help when comparing cameras. We think you’ll find it useful.

Up until now, the sensor sizes have been provided as slightly obscure imperial fractions that hark back to a set of standard sizes given to TV camera tubes in the 50’s. This is industry standard practice but by no means intuitive. To get around this, we’ve researched the common sensor sizes and used them to calculate a value we’re calling ‘Pixel Density.’

Pixel Density is a calculation of the number of pixels on a sensor, divided by the imaging area of that sensor. It can be used to understand how closely packed a sensor is and helps when comparing two cameras with different sensor sizes or numbers of photosites (pixels). Because the light collecting area and efficiency of each photosite will vary between technologies and manufacturers, Pixel Density should not be used as an absolute metric for camera quality but instead to get an impression for how tightly packed the imaging chip is.

Pixel Density now appears in our database and will appear when you look up a specific camera or when you conduct a ‘Side-by-side’ comparison in our Buying Guide. We’ll also add it as a search criterion in the Buying Guide’s ‘Features Search.’

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