What Is A Digital Zoom?

A digital zoom is when a camera recreates the effect of zooming in with a lens by capturing the image from an increasingly smaller area of the camera’s sensor, and then blowing up that image to the regular size.  It appears as if the lens is zooming in, but in fact the effect is purely software based and has nothing to do with optics at all.  The smaller the area used on the sensor to capture the image, the larger the zoom effect appears to be.  The problem with this method is that it decreases the quality of images progressively as you zoom in further.  The camera will interpolate the small image it has captured in the middle of the sensor, up to the same pixel size as if you had used the whole sensor.  Detail will be lost, there’s no getting around it.  Just as if you take a regular photo that didn’t use a digital zoom, and blow it up to twice the size in Photoshop.  The process is the same and you would expect to lose some quality.

Digital zooms are often found on cell phones, which do not have space for any kind of optical zoom internally.  They are also quite common on point and shoot cameras.  Many of those cameras will have an optical zoom that turns into a digital zoom at the end of its travel.  Be careful when you check the specifications before your next camera purchase!  You want to base your choices on the length of the optical zoom because this is where the quality is.  I would recommend only using a digital zoom in an emergency.

 

Additional Reading

  • What Is Interpolation?
  • What Is An Optical Zoom?
  • What Does Field Of View Mean?

 

 

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A camera with a 42x optical zoom and a 4x digital zoom