We’re continuing our investigation of camera filters this week, taking a look at Neutral Density filters and Graduated ND Filters. These give you a large degree of control over the exposure in an image, and are brilliant for water and landscape photography.

What Does a Neutral Density Filter Do?

A Neutral Density filter allows a photographer to control the exposure in an image very easily. The filter stops light reaching the camera sensor, therefore allowing us to leave the camera with a higher aperture for a longer amount of time.

Instead of changing the aperture to reduce the amount of light in the image, we simply add on a ND filter, then adjust the exposure to the amount we want. It is easy and very effective, plus we can still set the aperture to a low value for sharper images, or wide open for a shallow DOF.

ND filters do not effect the colour in the photo in any way. What you see is what you get. This is a big difference compared to the Polarizer filter.

Photographers commonly use a ND filter when shooting water as it blurs the moment, and you get a smooth silky look. Without the ND filter, most cameras are unable to find an aperture small enough to get the same effect.

Other helpful uses of ND filters include:

• Reducing the depth of field in bright sunlight
• Adding motion blur to moving objects
• When using a wider aperture

What Is a Graduated Neutral Density Filter?

It’s the same as a ND filter, but graduated! This simply means that the ND effect is not on the whole of the glass, it fades gradually as the name suggests.

This is useful because photographers often want to darken the sky, but leave the foreground as it is. To do this you simply move the filter up and down in the holder to match the landscape you are shooting.

Disadvantages of using a graduated filer include the fact that often the landscape is not flat like the straight edge on the filter.

You can buy different graduated ND filters depending on the effect you are after. You can get a soft edge which has a large fading distance or a hard-edge with a sharper quicker fade.

The image below shows a use of a graduated filter. The left photo has no filter attached but the image on the right has a 2 stop Grad ND filter. As you can see the sky shows up perfectly.

What Different Types Are There?

You can get different strength ND filters to block out more light than others. This is very useful, but also requires you to buy more expensive filters, as well as know this very large F stop chart pictured below (click for larger version)

The most common kinds are a 1 stop, 2 stop and 3 stop filter. You can also purchase a 10 stop filter if you really want to slow things down. If you don’t understand f stops, check out Phototuts+ Basix tutorial!

An example would be if you are shooting at f11 with a speed of 1/500, then decided to use a 10 stop filter with the same aperture then you’ll get an exposure of 2 seconds. This is quite a large jump and you will need to use a tripod no matter what.

If you are using a filter holder remember you can double the filters up. So you can put a 3 stop and 2 stop on top of each other. Useful, but beware of vignette around the final image.

Recommended Brands

LEE filters:

• LEE Filters 4×6" Graduated ND Resin Filter Set (0.3, 0.6, 0.9) – Currently $245 – Requires the LEE filter holder
• LEE Filters RF75 Standard Neutral Density (ND) 0.3 Filter – Currently $110 – Requires the LEE filter holder

Cokin:

• Cokin H250A P-Series ND Grad Kit – Currently $60 – Requires Cokin P holder
• Cokin CU960 Pro ND Graduated Filter Kit – Currently $165 – Pack includes filter holder

Hoya:

• Hoya HMC NDx8 – Filter – neutral density 8x – 77 mm – Currently $54 – Screws into lens.

Dolica:

• Dolica CF-NDK72 72mm 0.3, 0.6, 0.9ND Neutral Density Filter Kit – Currently $50 – Screws into lens.

The LEE filter is aimed at professionals and has the price tag to match but if you are looking to try out playing with ND filters why not pick up a cheaper set made by Dolica? Good quality for the money and they work a treat.

Further Reading

If you have found the subject interesting then you might want to take a look at these articles:

• Achieve Beautiful Landscape Photos with a Neutral Density Filter
• Darken Skies by Replicated ND Grad Filter Effects in Photoshop
• How to Use a 10 Stop Neutral Density Filter

Thanks for Reading

If you own a ND filter please post up your photos – we always take the time to view them all. Also, if you would like information on any other filters, please feel free to leave a comment with your question!