This glass filter adjusts a sensitivity of CCD and CMOS image sensors (which are used in digital cameras such as cell phone cameras, security cameras, and vehicle cameras) to the spectral sensitivity of the human eye. It features a basic composition of fluorophosphate glass, so it has outstanding acid resistance, water resistance, and strength.
Effect of NF glass filter
A comparison between a NF glass filter and a reflection type filter by AGC in the cameras of the same model is shown in the below picture. In Picture 1 and Picture 2, ghosting and flares which occur in the center of the flame of the candle are restricted by using a NF glass filter, ensuring that a more natural color is displayed. In Picture 3 and Picture 4, strong ghosting and flares which occur due to the sunshine filtering through the foliage are restricted by using a NF glass filter, making the shape of the trunk of a tree clear, and the leaf color displayed in a natural color.
Principle of restricting ghosting and flares
Example of configuration from lens to image sensor is shown in the below figure. In a reflection type filter, the reflected light from the image sensor surface is reflected again with a UVIR cut film, and multiple reflections occur between the two surfaces. On the other hand, in the case of a NF glass filter, significant reduction of ghosting and flares is made possible as infrared wavelength which is unnecessary light is absorbed. This effect is more remarkably demonstrated in a photographing in which the lens is turned towards the light source like a backlight, etc.