A ND filter is essentially a dark piece of glass that reduces the amount of light entering the lens. For this project, the ND filter will reduce the amount of light by 10 STOPS! Why would anyone want to reduce the amount of light entering the camera? Well, by reducing the amount of light, we can use a slower shutter speed. This will create motion blur (great for moving water). Another popular reason for using a ND filter is to use a larger aperture, creating thinner depth of field without over exposing. If you want to know more about ND filters, check out the Wikipedia article: http://en.wikipedia.org/wiki/Neutral_density_filter.
If you're ready, lets begin.
Things you will need:
- Welder's Glass/Lens Green Shade #10, <$10 on Amazon
- DSLR or camera with manual controls
- Lens or lens adapter that accepts threaded filters
- A spare UV filter. These are pretty cheap, sometimes free if you buy camera related items on sites such as Amazon
- Remote for your camera
- Lens cleaning supplies
- Black or dark electrical tape. Must be dark to prevent light leaks
- Working knowledge of long exposures
- Optional: Step down rings