Day/Night vs IR Cameras

JH
John Honovich
•Published Jun 22, 2012 00:00 AM
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When low light image quality is critical, Day/Night and IR cameras are two of the top choices. But how do these two differ and when should you choose one versus the other? In this note, we explain.

Key Similarity

The most important shared aspect are that they both can see 'infrared' / non-visible light. By seeing that light, they can deliver a brighter, more detailed image during times when visible light is poor. While humans cannot see it, even when it is dark out, some non trivial amount of IR light is 'shining' (background: see our IR measurement review). Both camera types can make use out of it.

By contrast, color only cameras, by design, filter out IR light. This is why day/night is preferable to color for low light scenes.

Key Difference

The key difference between day/night and IR cameras is that day/night cameras can only see IR light but they cannot produce it, unlike IR cameras. Indeed, the name 'IR camera' typically implies that the camera has an IR illuminator built into the camera itself.

IR camera's key advantage then is that they can 'see' IR light plus they can shine their own IR light. Therefore, in scenes that are especially dark, IR cameras typically can deliver a brighter image than a day/night camera can.

Why Use IR Cameras

The main reason to use IR cameras over day/night ones, then, is when the the scene is really dark and you cannot (or will not) add visible light. The day/night camera might then deliver an unusable image while the IR camera should be better.

Limitations of IR Cameras

Integrated IR cameras are gaining in popularity, and at a premium of ~$100 more than day/night cameras with the same feature sets are a fairly inexpensive option. However, keep in mind the following drawbacks of many integrated IR cameras:

  • Short range: Typically only specified up to 50 feet, many only produce a useable image for 20 to 25 feet. See a test result.
  • Blooming/glaring: Objects/subjects close to the camera often are wash outed from too much IR light though some offer automatic adjustment. See our discussion [link no longer available].
  • Bugs/insects: Many integrated IR cameras attract bugs and insects. See our discussion [link no longer available].

That noted, IR cameras are used by more than half of integrators. Some integrators default to using IR cameras for any scene that is dark while others use them only if a specific issue arises with day/night cameras. A big factor in the choice is how good your preferred day/night cameras are in low light. Top day/night cameras can be very good (see our low light MP test results). However, those cameras can be very expensive (~$1,000). By contrast, cheap IR cameras that simply slap on some IR LEDs can be half that price or less though with many of the limitations noted above.