Life as a photographer requires improvement from each level of your experience. From being able to centralize your image, to good composition and knowing the amount of light you require to have a good shot or even controlling your aperture and shutter speed to the right settings.
Neutral density filters help you produce better image quality more than and different from the one taken by ordinary cameramen. It brings out the professionalism in your image.
Neutral Density Filters:
As the name goes, they are filters that control and modify the intensity of color and light. Some are colorless or grey colored. They are essential in reducing the amount of light entering the lens or your camera. This helps photographers to select aperture, shutters speed that is over-exposed which produces blurred images.
A sport photographer may wish to take a picture of a player in motion but maybe another player is in front of him or even the referee, ND filters help to blur the referred while focusing on the player while using a shutter speed of say 15 sec which might allow much light in the day, but ND filters produce good motion blur.
ND filters give you the freedom of overexposing your camera with a wider aperture in daylight as it functions to absorb all light coming to your camera while still overexposing to give you the effect you desire. ND filters give you new possibilities beyond your aperture and shutter speed.
Its application includes the telescope which causes the moon appear more bright with no contrast, also in movies and films where the subject is in front of a window gelled with ND filters
1. The graduated ND filter: This has different intensity in filter surface. Usually used for images bright on one side e.g the sunset image. Its transition area is in varieties also: soft, hard and attenuator. The soft transition area is the most common.
2. ND- filter wheel:This has a two glass disk opened with a denser coating applied around the opening on each disk surface. Rotating these disk facing each other enabling them to go from 100% transmission to 0% transmission. They are found in catadioptric telescopes.
Note: Due to the disadvantage of having to carry different ND filters,(it’s quite costly though it accounts for flexibility in shots) Manufacturers of ND filters have created the variable ND filters that have more than one polarizing filter. This variable filter has provided photographers with many filters in one set.
ND filters are rated using the f-stop reduction or the optical density. They are also noted using the ND numbering e.g ND2, ND8. ND2 allow half of its light to pass through it, ND4 allow 1/4(one-quarter) of its light to pass through.
Halving amount of light passing through reduces light coming through by one F-stop, ND4 reduces light entering by two F-stops. This helps you calculate the amount of light you need for a shot, it also helps aerial photographers in taking pictures of the sky and the land, without having to overblow your image.
When you are taking a normal shot with aperture of F25 or 50 and shutter speed of say 2 secs, for a properly exposed photo, hesitating even a bit beyond 2 secs would blow out your image, making it too bright but placing an appropriate ND filter on your camera (e.g ND46 and ND8) effectively reduces the light.
Note: ND filters are not that perfect or complete, they do not reduce wavelengths equally, creating color cast and differences in images. Some are limited to some amount of light in the spectrum, hence not being able to block some UV light and infrared. This is very dangerous and a risk to a photographer especially when he tries to view the sun or a kind of light.
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