Night vision devices, such as night vision monoculars, night vision binoculars and nightvision riflescopes and digital night vision, have magnification values that is displayed using the same terminology as their day time counterparts.
The biggest difference you will see is that for all night vision devices, magnification values are significantly lower than that for day time devices. For example, most night vision monoculars have magnification values of 2x to 4x, night vision binoculars have values between 3x and 5x, riflescopes between 2.5x and 6x and digital night vision magnification sometimes goes as high as 8x. The main reason for this phenomenon is that night vision devices are dependent on the amount of light (whether visible or infra red) that is reflecting from the object of observation back into the device. Since observation is taking place at night and the amount of light is a lot less than what is available during day time – the device has a lot less light to work with in order to construct an image visible to the observer. That light has to be amplified (see section on How Night Vision works) before it becomes an image visible to the observer and during this process of amplification some of the additional magnification is lost.