Many questions have arisen around filters, but none we feel are more promiment and important than those which have to do with light control as compared to the ones that are for effect. In this in mind we ventured to explain the pruspose and difference of ND filters.
So what are ND’s and IRND’s and what are their differences?
Neutral Density filters (or ND filters) reduce the amount of light passing through the camera lens without changing the color of the scene. Infrared Neutral Density filters (or IRND filters) have the same effect as ND filter but on the infrared scale of the spectrum.
· Especially useful in bright light conditions to help prevent overexposure and achieve a balanced exposure.
· Allows specified exposure when desiring to expose at large apertures despite being present in bright lighting conditions, which normally require small shooting apertures.
· Neutral Density filters allow aperture control for selective depth of field shooting.
· Most popular Neutral Density filters are ND 0.3, 0.6, & 0.9. (ND 0.6 is most popular.)
· These above filters hold back 1, 2, & 3 f:stops of light respectively.
· The above-mentioned ND filters are also referred to as 2X (ND 0.3 -1 f:stop), 4X (ND 0.6 - 2 f:stops) and 8X (ND 0.9 - 3 f:stops)
ND FILTER % LIGHT TRANSMISSION f:stop REDUCTION
0.1 80 1/2
0.2 63 3/4
0.3 50 1
04 40 1 1/4
0.5 32 1 ¾
0.6 25 2
0.7 20 2 1/4
0.8 16 2 3/4
0.9 13 3
1.0 10 3 1/4
1.2 6.3 3 3/4
1.5 3.2 4 1/4
· Neutral Density filters are available in Color Grad Neutral Density filters consisting of half dear glass graduated to half neutral density. This allows for a smooth blending of the scene and proper balanced exposure in uneven lighting situations.
· Color Grad Neutral Density filters are available in ND 0.3 (1), ND 0.6 (2), and ND 0.9 (3). You must specify graduated effects in "Hard Edge" or "Soft Edge" and "Horizontal" or "Vertical" format.
OK great but what is the difference then White Water vs Regular ND or IRND Filters.
Due to the process and silica used in the manufacturing of the filters a blue or green “aura” is visible when light passes through. In the case of the white water filters (indicated with a w in front of the filter code) a higher end silica is used. When light is passed through the filter processed with the higher end white silica there is hardly any color “aura” providing a clearer aura less image.