Every Photographer and Videographer Needs This | GFF Ep. 8

Every single person who owns a camera should be using an ND filter, particularly those who shoot outdoors! I know that is an incredibly bold statement, but allow me to explain in this week's Gear Focus Friday. First of all, what is an ND filter? ND stands for Neutral Density, which means it cuts down on all waveforms of visible light equally. In essence, this is a filter that reduces the amount of light entering your camera's sensor. Typically that sounds like a bad thing, but it's really not.

Why would I want to reduce the light hitting the sensor?

In order to achieve a shallow depth of field in our images, our apertures need to be wide open. This lets the most light possible into our sensor. However, if we shoot outside, or in an environment where the light is uncontrollable, we need to lower our exposure. Unfortunately, this usually means closing our iris to reduce our aperture. Consequently, this makes our depth of field deeper, reducing our cinematic look. You can see the increase of DOF in these sample images: So obviously without the ND filter, image #2 above is way overblown and not usable. And when you go down to f/3.2 to compensate, you lose a lot of that shallow DOF from the first photo. Compare the two side by side: It's easy to see how much shallower your subject can be with a lower fstop. Just look at the sledgehammer above! Another way to look at this is in the photo world, particularly in long exposures. Say you want to take a long exposure of a stream, so the water in the shot is blurry and smooth, but its in the middle of the day. Chances are, if you take a long exposure shot, you image is going to be way over-exposed. If you increase your shutter, you're going to loose the flow and smoothness in the water. Check out this sample below from a backyard stream: Now with a higher-rated ND filter (and faster moving water!) you can really ramp this effect up and make some very cool images. The solution to both of these problems is an ND Filter. The ND will allow us to reduce the amount of light coming into the sensor without changing our settings, thus giving us the image we want!

ND Filter Types

There are several different kinds of ND filters. The most common are the Single Stop ND, the Variable ND, and the Internal ND. A single stop (stop explanation in video) filter is a single piece of glass with a stop reduction value. This is also referred to as a Filter Factor number such as ND32 which is the equivalent to a 5 Stop filter. A variable ND is just that. It is two pieces of glass that rotate against each other and cross polarize, reducing the amount of light. The amount the light reduced is determined by the angle of the two pieces of glass in relation to one another. These can be changed on the fly to work around different changes in light. The first two types of filters go in front of the lens. An internal ND goes between the lens and the sensor. It functions the same way that the other two do, except now you don't have to remove your filter when you switch lenses. Each one of the types of filters have a different set of pros and cons, but if we went into each of those in this blog post, we would all be here forever! So I will leave that for the video which you can see above. And of course, if you have ND filters that you no longer need, head over to Gear Focus to list them now for free! Let me know in the comments down below what your favorite types and brands of ND filters are. I would love to hear from you and learn about the gear that you use. Have a great weekend and I'll see you all next week!