This week one of my loyal customers asked me a brilliant question about Neutral Density filters. It was so good I just had to answer it via this article. You'll most likely appreciate this digital photography tip as much as he will.
"A question, I want to get a graduated filter, however, all the one's I see are graduated gray, are still still ND and will not affect the color? Very best regards, Pete."
What Pete's digital photography question is all about is the common confusion of photography equipment looking like something different to what we first expect.
When choosing a filter for our digital photography its best to first look at them as tools. Firstly in order to maintain clarity about ND filters, firstly think about what you need then work your way from there. Pete's a fantastic photographer and is ready to move to the next level with his digital photography equipment choices, which is where I come in.
The answer to Petes digital photography question is yes, they are still ND, but like all filters, the color will be affected. I'll explain.
ND filters are typically used to darken a bright sky so that both the sky and subject can be properly exposed. Graduated ND filters have varying degrees of "graduated gray." The Graduated ND filter comes in a few different types, but can really be broken down into two main categories. They are; hard edge and soft edge.
As the name suggested a Hard Edge is mainly applied when there is a sudden difference in the luminance of the digital photo, such as an overexposed sky over a landscape. The soft edge filter is primarily applied to a digital photo that has less distinct over and under exposed areas such as the same landscape but sometimes taken at approaching dusk when the light is not do hard. A soft filter just gently tones down hard areas of light. It's less dramatic and can often be used very well in black and white photography to give the digital photo a "boost" of the dramatic.
You can have a variety of ND filters that go from a poor graduated gray to quite a strong graduated gray. The "intensity" of graduated gray is described by numbers. So for example a weak graduated gray ND filter is known as "ND2X". And the strongest is "ND8X".
All filters affect digital photography color whether subtly or dramatically. You can have an ND filter that's quite soft but still darkens an area of the digital photography image. Even though it's subtle, anything you put onto that lens will be affected. But it depends what we mean by "affected."
If we mean the colors disappear and change completely … well a lot depends on that such as the intensity of gray, the color at the time of day, the seasons etc. If you are using a Full graduation from top to bottom then your colors will most definitely change. They will become darker. However if you are using a less intense ND filter, then you'll notice the change in color is not as apparent. You'll notice that the lighter ND filters will have more of a polarizing affect, the darker areas being at the top and not so much shading at the bottom.
Graduated ND filters are brilliant in times of excessive brightness coming from the top of the sky for example. You can use an ND filter to darken an overly bright sky and keep the main subject's luminance the same. It has a terrific influence over evening up unbalanced light. It can effectively tone down over exposed areas in your digital photography.