What is a Neutral Density Filter and what do you use it for?
A neutral density filter or ND filter – The purpose of a standard photographic neutral density filter is to reduce the amount of light entering the lens. Doing so allows the photographer to select combinations of aperture, exposure time and sensor sensitivity which would otherwise produce overexposed pictures. This is done to achieve effects such as a shallower depth of field and motion blur of a subject in a wider range of situations and atmospheric conditions.
Examples of this use include:
- Blurring water motion such as waterfalls.
- Reducing the depth of field in brilliant light.
- Add motion blur to subjects.
- To extend the time of the exposure.
For example, if you photograph a waterfall at a slow shutter speed to create the milky water effect. The photographer might determine that to obtain the desired effect a shutter speed of ten seconds was needed. On a very bright day, there might be so much light that even at minimum shutter speed and a minimum aperture, the ten-second shutter speed would let in too much light and the photo would be overexposed. In this situation, applying an appropriate neutral density which will allow less light to come into the camera and will enable you to have a longer shutter speed.
The use of an ND filter allows the photographer to use a larger aperture that is at or below the diffraction limit, which varies depending on the size of the sensory medium (film or digital) and for many cameras, is between f/8 and f/11, with smaller sensory medium sizes needing larger-sized apertures, and larger ones able to use smaller apertures. ND filters can also be used to reduce the depth of field of an image (by allowing the use of a larger aperture) where otherwise not possible due to a maximum shutter speed limit.
The two most common are the variable ND filters and the extreme ND filters such as the Lee Big Stopper.
Variable neutral density filter
The main disadvantage of neutral density filters is that to be entirely flexible in your shooting you need to carry a range of different NDs. This can become an expensive proposition, especially if using screw filters with different lens filter sizes which would require carrying a set for each diameter of lens carried. To counter this some manufacturers have created variable ND filters. These work by placing two polarizing filters together at least one of which can rotate. The rear polarizing filter cuts out light in one plane. As the front element is rotated, it cuts out an increasing amount of the remaining light the closer the front filters comes to being perpendicular to the rear filter. By using this technique the amount of light reaching the sensor can be varied with almost infinite control.
The advantages to this are that you get multiple ND filters in one package, saving money but the disadvantage is a loss of image quality caused by both using two elements together and by combining two polarizing filters. It’s up to you to decide which route you want to go. There is a review of ND filters below but we Like the Promaster Variable ND filter.
Extreme ND filters
To create ethereal looking landscapes and seascapes with extremely blurred water, or other motion has needed the use of multiple stacked ND filters. This had, as in the case of variable NDs, the effect of reducing image quality. To counter this, some manufacturers have produced high-quality, extreme ND filters. Typically these are rated at a 10-stop reduction, allowing for very slow shutter speeds even in relatively bright conditions.
Big 10 Stopper Extreme ND filter. We used this filter on our last trip. It is the kind you put on the outside of your lens. We used it for one trip, but every time the rain started our staff had to pack it up and walk to shelter, then pull it out again and reset it. It can be too much worry about. You can drop it and damage it during this in and out of the pouch time. It is an expensive item to drop, hence the worry.
Here is a shot. It is pretty impressive if you want to work and worry.
Here is our Favorite Filter Brand.
The ProMaster Digital HGX Variable Neutral Density Filter – variable neutral density filter providing the light reduction of about 1.3 to 8.6 stops. The ND3 to ND400 density creates a darkening of the entire image, allowing you to photograph with a wider aperture or slower shutter speed than normally required.
- Next Generation Digital Anti-Reflection Multi Coating – Specially formulated to minimize internal reflections created by CCD and CMOS sensors in a digital SLR.
- REPELLAMAX™ Element Resistant Coating – This EXCLUSIVE PROMASTER coating repels moisture, fingerprints, dust, dirt, and grime to ensure the sharpest images possible
- Hardened Optical Glass – Ultra hardened optical glass resists surface scratching and stands up to the most intensive use.
- Low Profile Anti-Reflective Frame – Ultra thin low profile frame helps prevent vignetting on super wide digital format lenses. The satin-like smooth finish helps to minimize reflected light.
- Black Rimmed Glass – The outer rim of the filter glass is treated with a special black ink
This is where you will click the link to purchase PROMASTER FILTERS as soon as we set it up for you. BE RIGHT BACK WITH THAT!
Video and comparison by Dave Dugdale – LearningVideo. We are now comparing the Promaster Variable ND Filter just as Dave compared the three. We like the Tiffen high end filters and we also love the Promaster Filters the Best!! Watch for our review shortly. We are out making it now. You can’t beat the Promaster Filter Quality. We will soon explain why you should buy Promaster.