TECH TIP: Neutral Density (ND) Filters

Most cameras come with built in ND filters that can be switched into the optical path so making it possible to select an aperture for the intense light we have in the West and the Southwest. Even so there are occasions where we want the aperture wide open - and for those additional ND filters may be needed. They come with a value that can be translated into f stops:

	Value	f stop increase
	ND 0.3 or 3	+1 stop
	ND 0.6 or 6	+2 stops
	ND 0.9 or 9	+3 stops
	ND 1.2 or 12	+4 stops

Screw-on ND filters are available in most popular sizes and also as filter squares for use with matte boxes, Cokin and similar systems. (Filters from B&H - price depends on filter size and quality ranging from under$20 to over $150.)