Optical vs Digital Zoom
Many COOLPIX cameras offer a digital zoom function to complement the camera's built-in optical zoom, digital zooms are useful when it is not possible to get closer to the subject without the need of an additional optical converter. However, the use of the digital zoom should be used sparingly as there is a sacrifice in image resolution and it should not be considered a replacement for a powerful optical zoom lens. Several COOLPIX cameras allow the use of optical converters that allow high quality telephoto photography, and should be used if possible instead of using the digital zoom to maintain image quality.
When using an optical zoom, the lens optics move to change the field of view using the full area of the camera's imaging sensor, this allows image quality to remain constant throughout the optical zoom range.
When using the digital zoom, the optical lens is set to the maximum telephoto setting of the zoom. smaller area of the sensor is then used to record the image. This image is then re-sampled back to the original size to produce an image equivalent in magnification to that taken if a more powerful telephoto lens was used. As a digital zoom setting is increased, a smaller and smaller area of the image sensor is used, thereby reducing the image quality in relation to the amount of zoom used.
Unlike an optical zoom, a digital zoom does not increase the amount of detail visible in the picture, therefore when using the digital zoom image quality is relative to amount of digital zoom used. The images below demonstrate the image resolution differences between digital zoom and optical zoom.
The same image was taken with a camera using an optical zoom at the telephoto setting and again using a smaller zoom setting plus digital zoom to produce the same magnification. The images shown on the left is highlighted in the red square.
Image taken using optical zoom only, cropped and resized for display on the web
Image taken using digital zoom, cropped and resized for display on the web
Note that the effects of digital zoom are not visible in the camera's optical viewfinder (if the camera has one) - use the LCD monitor / viewfinder when framing pictures with digital zoom. Digital zoom is not available in all camera modes, or when the camera's LCD monitor is off.