Wrong: Why Imager Size Is NOT Key To Low Light

By Ethan Ace, Published Feb 06, 2014, 12:00am EST

We hear it all the time: bigger imager means better low light performance. But is it really true? In this note we compare imager size to low light performance from our industry leading testing in order to settle this once and for all.

The Truth

1/3" inch imagers are by far most common in our tests (and in IP cameras), followed by the marginally larger 1/2.8" and 1/2.7" sensors. Cameras with these imager sizes, similar resolution, and F stop ranged from best to worst, and everywhere in between, illustrating the point: better gain control, noise removal, and other image improvements resulting from increased processor performance in recent cameras far outweigh simple imager size.

Here is our test chart with highlights showing how the same hardware specs (such as imager size) delivered radically different low light performance:

Imager Size Helps But....

Larger size imagers size can help but:

  • It gets really expensive to use larger imagers (especially 1/2" or above), both in the cost of the imagers and lenses to use with them. Aside from Avigilon's Pro series (the most common example of larger 35mm sensors in surveillance) and the new 1/2" imager Sony SNC-VB635, few examples are common in surveillance.
  • Moderate increases in imager size (1/3" to 1/2.7") are far less impactful than advances in gain control / image processing and newer images (same size but better). Our chart above shows the same imager sizes delivering radically differing low light performance due directly to far better processing.

Image Processing

You see many names for 'super' low light performance - LightFinder, LightCatcher, StarLight, Super Light Enhancer, etc. - what they all have in common is (1) advanced image processing and (2) similar size imagers.

What To Do?

We understand that it would be easier to simply look up the imager size on a spec sheet and conclude that the larger imager is best. The reality, though, is that is a bad metric to use. 

1 report cite this report:

Axis Large Imager HD Camera (Q1635) on Dec 16, 2014
Many surveillance professionals love large imagers. Axis is feeding into...
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