Good Evening,
Today the little ones and I went to Red Rock Canyon. I brought along some ND filters to show what they can do.
ND filters are basically like putting sunglasses on a camera. They darken the whole thing. There are a few reasons to want to do this. Wanting to use a large aperture to have a shallow depth of field, wanting a long or longer exposure time, making flowing water silky, removing people from a busy location. They come in different strengths. Just like CPL filters they can be costly and we can buy one set for our largest thread lens and then step rings for the rest of the lens. Ultimately we want a filter that darkens the frame evenly without adding a color cast.
I did not use an ND filter for either of these images. I was testing a new lens and seeing what I could get out of it. I was planning on taking some water images today but alas didn't get the chance as there hasn't been any recent rain. This does give an idea of what an ND filter can do to a scene though.
There are also graduated ND filters which are used to darken a bright sky over a landscape so both can be seen. They come in both screw on filters and in a square filter with a holder. Just like the regular ones also come in different strengths.
Here is what I shot today with the girls. Notice both are about even on the ground but with the grad ND the sky looks better and not as blown out. For a scene like this I should have had the grad tilted more toward the sun on the left. I tried it but wasn't paying attention and got my finger in the frame because I was talking to children.
As for removing people from scenes I have pictures of them removed but no before shots. If I go to a populated area where people are moving I will get it. Until then see where an ND might fit into your needs. Now go out and shoot.
~Scott