Neutral Density filters are darkened plates of glass that reduce the amount of light that reaches a camera’s sensor. They can create captivating effects and are a staple in many landscape, travel and architectural photographer’s bag. Undoubtedly there most popular use is to blur running water, most famously waterfalls, to create a soft, feathery look. But this versatile filter has a lot more to offer.
When shooting in sunny, cloudless skies, conditions are far too bright for cameras to shoot slower shutter speeds. Even after stopping down the aperture to f/22 and reducing the ISO to its lowest sensitivity, you’ll be hard pressed to have a shutter speed longer than one second. This isn’t long enough for the most interesting effects this filter can produce. To do that you’ll need to get that shutter speed down to 10 seconds or longer.
This is where a ND filter comes in. By reducing the amount of light reaching the camera’s sensor, the filter allows dramatically lower shutter speeds.
ND filters reduce light by as much as 10-stops. Every stop represents a halving of the amount of light, so a 10-stop ND filter reduces the light passing through to the sensor by a factor of 1000! They come in various stop reductions and you can stack them to get even more flexibility. There are even variable stop ND filters available. These allow you to dial up the desired reduction of light.
While there are many brands of ND Filters on the market, the cliché you get what you pay for is true. It makes little sense to put a piece of $20 glass on a $2,000 lens. If you are serious about the quality of your photographs, skimping on lens filters in not the place to save. A $20 filter is almost sure to degrade the quality of the image. Be prepared to spend around $80 or more for a quality ND Filter. My favorite filter brands are Hoya, B + W and Nikon.
How to Use ND Filters
There are a lot of creative uses for ND filters, but it starts with deciding on a shutter speed. The longer the shutter speed the more blurred the movement becomes.
Most DSLR cameras are limited to a minimum shutter speed of 30 seconds. Any longer than that and you’ll be shooting in Bulb mode, which will require a cable release for your camera. If you want to capture an even longer exposure you’ll need to shoot in Bulb mode and use a shutter release cable.
Follow these 5 easy steps to shoot your own artistic long exposures. Below is a step by step guide to shooting a waterfall to create a feathery look for the water.
Step 1
Use a Tripod! Unless you are attempting some artsy smear of light you absolutely must have your camera on a rock-solid mount. The slightest movement during long exposures will create problems. If there is a breeze, hang a weight on your tripod collar. (Some tripods have hooks for just this purpose).
Step 2
Set your camera to Manuel mode.
Adjust your ISO to 100 or lower.
Set the desire aperture setting to give the depth of field you want. If in doubt start at f/8.
Spot meter on the waterfall. Adjust your shutter speed to the ensure the proper exposure.
Step 3
Switch to live view. If your camera doesn’t have a live view capability, then auto focus on the subject.
Switch the camera and lens to manual focus mode.
Compose the scene, focus by enlarging the view and carefully focusing using the manual focus ring.
Take a test shot. If everything looks right, you’re ready for the next step.
Step 4
Screw the ND Filter on the front of your lens.
Slow down the shutter speed to 20 seconds.
Cover the viewfinder. Some cameras have a built in curtain that has a switch to lower it across the viewfinder. A piece of tape or even a piece of cloth draped over the viewfinder can work as well.
Take a photo using the self-timer or shutter release cable.
Check the image for proper exposure and effect. If the image is over or under exposed, change the shutter speed accordingly.
Want more info? Join Tony Avila and myself for a in depth podcast on the subject of filters over at Aperture Priority.
About the author: JS Engelbrecht began his photography career in a High School dark room for the school's Year Book. Later he entered the fashion industry and product photography before turning his attention to Nature. "I moved from shooting pictures of beautiful jewelry to shooting pictures of natural beauty."
Now JS Engelbrecht enjoys capturing beautiful scenes during his travels. He is also a gifted teacher and guide for local photographers. Click here to see his fine art gallery.