The 100mm Graduated Filter Kit 5 from Hitech is designed for the Cokin P system. The three filters in this kit offer the possibility to achieve otherwise unachievable results. This kit includes 1, 2 and 3 stop Graduated Neutral Density filters. They enable the shooter to adjust exposure without affecting color balance.
An ND filter appears gray and reduces the amount of light reaching either the sensor of a digital camera or the film plane of a traditional film camera. A Neutral Density filter is also used to create some unusual special effects such as capturing the "blur" of the rippling water of a waterfall or the swirling effect of city traffic.
Since it allows the use of slower shutter speeds in bright light, it becomes possible to create these special effects that would normally not be possible to capture without the filter. And since it can also help to control your depth of field, it permits you to shoot at wider apertures. Ultimately, its value is in helping to prevent bright, overly washed out images shot in bright light.
Graduated Neutral Densities are primarily used to control the exposure between a dark foreground and bright sky. The Graduated Filters in this kit are hard edge. Soft edge grads have a smooth transition from clear to ND. Hard edge grads have a more defined hard lined transition and should be used for longer lenses.
Their CR39 resin is manufactured in large sheets that are oven cured. Their exclusive Absorbing Cell Technology absorbs color as opposed to other filters that are coated. Once cured, they are sliced up to create individual filters. In this way, maximum consistency is maintained from filter to filter. This becomes crucial when you wish to change filters either mid shoot or from day to day.