What does the multiplying factor mean?
Almost every filter holds back a part of the light (absorption) by virtue of its monochromatic character. This loss of light is compensated for when taking the picture by a corresponding increase in the exposure. The required correction value is called the multiplying factor or the filter factor. The factor itself is indicated on every B+W photo filter. The factor can also be found in your brochure.The multiplying factor is not a constant; rather, it varies according to the lighting conditions and the kind of film. As part of the filter information, the factor most used for daylight is given. Depending on the situation when the picture is being taken and on individual preferences, it is always possible to adjust these values. Of course, instead of increasing the exposure time, the aperture can be increased to obtain the necessary amount of light.The factor does not mean increasing the diaphragm or the exposure time by the value indicated. When the indication is 2x, this does not mean,
