Page 125 - (DK) Advanced Photography Guide

FILT ER S 123

FILTER STRENGTH TYPE OF FILTER FILTER FACTOR F-STOP ADJUSTMENT

A filter’s strength is shown as a filter factor SKYLIGHT / UV 1X NONE
value, which indicates how much light is
blocked by the filter. A filter with a 1x filter ND 0.1 1.3X 1/3-STOP
factor allows 100% of the light to pass
through and does not affect exposure. ND 2 / ND 0.3 2X 1-STOP
A filter with a 2x filter factor blocks 50% of
the light that falls on it, requiring a 1-stop POLARIZER 4X 2-STOPS
exposure adjustment. A filter’s name usually
incorporates a description of the filter’s ND 4 / ND 0.6 4X 2-STOPS
strength (such as ND 64). Manufacturers ND 8 / ND 0.9 8X 3-STOPS
also use a decimal value to describe filter
strength. This system starts at 0.1 for 1/3- ND 64 / ND 1.8 64X 6-STOPS
stop filtration and usually increases by 0.1 for
every 1/3-stop increase in strength. ND 1024 / ND 3.0 1024X 10-STOPS

EXTREME ND FILTER ND GRADUATED FILTER

Extreme ND filters are available in strengths from 6- to 15- Graduated filters help balance the exposure between two
stops. As they severely restrict the amount of light entering the areas of a scene in which there are differing amounts of light.
lens and make it possible to use shutter speeds of one second One half of the filter is semiopaque, like a standard ND
or longer, they produce extensive blurring of movement. filter, but the other half is transparent. The transition
The density of extreme ND filters means that you have to between the two halves may be soft or hard. It is best to use
compose the photo and set the focus before you attach an ND graduated filter in a holder system, as you can then
them to the camera, as once they are in place you cannot move it up and down or rotate it to find the right position
see through the optical viewfinder. Using a tripod is a must. to allow the appropriate amount of light through.
BEST FOR BEST FOR

◾ ◾ Blurring movement to remove detail entirely ◾ ◾ Balancing the exposure of bright skies with that of darker
◾ ◾ Landscape photography, particularly seascapes foregrounds
◾ ◾ Side-lit portraits or still life photography
◾ ◾ Minimalist black-and-white photos
◾ ◾ Adjusting the exposure of brightly sunlit snow or sand

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