Understanding Neutral Density Filter – ND Filters

What Is a Neutral Density Filter?
Filter Neutral Density (ND) filter is a major for long exposure photos. ND filters are no different from the physical shape and fitted with a polarizing filter in front threaded lens, look at the photo below. ND stands for Neutral Density, Neutral said more or less because it does not change the direction and character of the light. While the word Density because it reduces the intensity of the light. So more or less could be interpreted as a useful filter to reduce the intensity of the light, but does not change its character.

ND Filter Ideal Concept
A perfect ND filter should cut the light evenly. This means that they will not change color. If you are photographing an object, fitted or not fitted with filters ND should have exactly the same color. In fact, the optical quality of a ND filter will affect the tonal and color. See photo below, after the ND filter fitted, color images tend to yellow than before the filter fitted.
Uses and How it Works ND Filters
The primary use of a neutral density filter is to reduce the amount of light entering the lens. Application filters in general is to take pictures in a long exposure time.

Photo to the left (without filters) have the following exposure parameters: shutter speed of 1/8 sec and f/16 aperture, while the right photo (I put 10 stop ND filter): 58 seconds and f / 8. You can see the effects of what can be achieved when the ND filter is installed, look at the shape of the original water fall looks ordinary becomes soft like cotton.
If you ever wear sunglasses or being in cars with window film, a very bright initially be a bit dim not? Well, a neutral density filter has the same working principle: reduce the light. The difference is that less light is the light coming through the lens into the camera sensor DSLR or mirrorless you.
How Much Light The Minus ND Filter?

The darker ND filter more and more light is reduced.
ND filters have a specific notation to indicate how much they were able to cut out the light. For example, the brand ND filter B + W B + W with notation 106 means filter is able to reduce as much as 6 stop light. Hmmm, okay if you say stop making you confused, please read the article about stop here before heading further afield, if you are not moving on.
Reduced light can be translated as 6 stop in the field as follows: let’s say you find a waterfall  a very sunny day and wanted to make cotton water effect like this photo.

You do metering (what is metering?) And your DSLR camera in aperture priority mode (aperture priority?)
When the aperture is set at f/11 figures, obtained a camera shutter speed 1/250
Due to achieve the effect of cotton like the photo above water needs (example) a slow shutter speed of 1/4 seconds, so you spend 6 stop ND filter to darken the state
From the initial measurement 1/250 sec
Down 1 stop is 1/125 sec
Down 2 stop is 1/60 sec, etc. …
Until stop is down 6 1/4 sec.
Binggo waterfall effect soft cotton with ND filter.
Okay, so first. The article further on the ND filter you can wait in the near future.