The 1/2.5" sensor size indicates the physical dimensions of the image chip in a camera. This value, expressed as a fraction of an inch, does not directly describe the sensor's diagonal, but stems from a historical designation. For comparison, the smaller the number in the denominator of the fraction, the larger the sensor. For example, a 1/1.7" sensor is larger than a 1/2.5" sensor. The physical size of the sensor influences the amount of light it can capture. Larger sensors generally provide higher quality images with less image noise, which is graininess particularly visible in photos taken under poor lighting conditions. The chip size also influences the depth of field, i.e., the degree of background blur behind a focused object. Sensors of this size were commonly found in older compact cameras and mobile phones.