Soft And Hard ND Grad Filters: The Differences And When To Use Them

Without an ND grad                                                                  With a Cokin 121M ND grad filter               

Neutral Density Graduated filters (or ND Grads for short) are extremely useful filters that can vastly improve landscape images where both the land and sky are present in the shot. There are two main different types of ND Grad filters, and here we'll run down the main features of each type and why they're useful in your photography.

Just like non-graduated ND filters, which you can find out more about in our ND filters guide, graduated ND filters whether hard of soft come in different strengths, affecting the amount of light that can get through and changing the effect the filter has on the image. The stronger the filter, the more stops difference there is between the part of the image affected by the gradient and the part not. Basically the stronger the ND filter, the longer the shutter speed used can be before the image is overexposed. 

With graduated ND filters, the ND effect of the filter is only used on roughly one-half of the filter. This allows you to balance out a bright sky with the land, for example. If an ND graduated filter isn't used when photographing landscapes with a lot of contrast, the sky will be overexposed to compensate for the land or the land will be underexposed and silhouette-like to compensate for the sky. ND grads allow for a more balanced exposure. 

Hard ND grads

The term 'hard' is used to define the line between the ND half of the filter and the clear half. The change between the two in the middle of the filter with hard ND grads is sharp and stark. This makes them ideal for use when you have a clean, straight horizon line with nothing in the foreground or background of the image interrupting the horizon line. For example, seascapes or low-lying fields or rocks with no trees. 

Soft ND grads 

With soft ND grads, the change from ND to clear on the filter is more gradual. The effect gently fades out, and there is no definite 'line' in the middle where the ND part of the filter ends. Soft grads are ideal when you have objects encroaching on your horizon line such as trees or buildings as the softness of the grad will allow you to keep the sky at a similar exposure to the ground with no harsh line to be shown on the encroaching object.

Filter Systems

Both hard and soft ND grads are available as round screw in filters such as those from Hoya and Kenko in various diameters and strengths. On most modern lenses these days the filter thread doesn't rotate, so there's no need to worry about the effect appearing wonky or the wrong way up in your images. 

Square format filters, such as Cokin, also have ND grads available. The added benefit with square format filters is that you can move the filter up or down to get the filter graduation just right on your image without having to tilt the lens to make the picture fit the filter. 

Have a look at the ND filters section on Filterzone to see how ND grads can help to improve your landscape images.