Hoya 72mm NDX4 HMC Filter
Neutral Density filters are often ignored by photographers, but they have several uses and offer the possibility to achieve otherwise unachievable results. ND filters appear grey and reduce the amount of light reaching the film, they have no effect on colour balance.
The Hoya HMC NDx4 Filter decreases the quantity of light entering the lens by 2 f/stops, permitting wider apertures to be selected. This is perfect for portraiture to shrink depth of field. Subject appears crisp and clear while the background becomes a soft blur. The ND4 Filter is widely used for subjects such as waterfalls and other nature scenes to blur the moving elements and emphasize the movement.
Four main uses:
1) To enable slow shutter speeds to be used, especially with fast films, to record movement in subjects such as waterfalls, clouds, cars, seas etc.
2) To decrease depth of field by allowing wider apertures to be used, which helps separate subjects from their background.
3) To decrease the effective ISO of high speed film (ie: above ISO400) and allow it to be used outdoors in blight situations.
4) To allow cine and video cameras (which have fixed shutter speeds) to film subjects such as snow, sand or other bright scenes which would normally cause over-exposure.
Neutral Density Factors
• 2x = ND.3 (exposure adjustment = 1 stop, reduces ISO 1/2)
• 4x = ND.6 (exposure adjustment = 2 stops, reduces ISO 1/4)
• 8x = ND.9 (exposure adjustment = 3 stops, reduces ISO 1/8)