Neutral Density Camera Lens Filters
Neutral density filters provide photographers with a simple way to take pictures even on the brightest days. By cutting down the amount of light entering the camera, they provide more freedom to alter camera settings to create different effects.Purpose
Over-bright lighting can ruin a photograph through overexposure, making the highlights too light and washing out details. While camera controls allow you to avoid overexposure, all of the options come with tradeoffs. Reducing the lens aperture increases depth of field, setting the shutter speed faster can prevent the appearance of motion and on a bright, sunny day you may well already be shooting at minimum ISO. Neutral density lens filters are used to reduce the amount of light that enters the lens of your camera without having to make those trades. They allow photographers to use a wider range of settings to create artistic effects, and are particularly popular with landscape photographers who often have to deal with bright sunlight as well as anyone interested in shooting long exposures. They are called neutral density filters because they reduce all wavelengths of light equally, preventing any alteration to the colour balance.Sizing
Circular neutral density lens filters come in a variety of sizes. DSLR camera lenses typically feature threads around the lens for installing filters securely. However, this also means that you need the right size, otherwise the filter will not fit. Filter sizes in millimetres are typically printed somewhere on the lens, often next to the mathematical sign for diameter. Square neutral density filters provide a way to get around the problem as they fit over the front of the lens. This also allows you to use the same ND filter for all of your lenses.Types
Neutral density filters come in a range of different strengths. The darker the filter, the more light it blocks out. ND filters may be rated in terms of their F-stop reduction, their optical density or their ND factor. Each 0.3 points of density rating is equivalent to one F-stop. In all cases, higher numbers are darker than lower numbers. There are also some more specialised types of ND filter. Graduated neutral density filters are darker at the top and lighter at the bottom, allowing you to reduce contrast in the image to bring it within your camera’s dynamic range. Landscape photographers often use them to reduce the sky’s brightness without darkening the land as well. Variable neutral density filters are typically a more expensive option but can be darkened and lightened as needed.