ImageEffects namespace not appearing in UnityStandardAssets

I need to use the depreciated depth of field image effect, and to access it via code, however when I try to include it with

Code (CSharp):

1. using UnityStandardAssets.ImageEffects;

Visual studio warns me that using ImageEffects does not exist within the UnityStandardAssets namespace, and I am unable to access depth of field elsewhere in my code.

Checking DepthOfField.cs though, I see the following:

Code (CSharp):

1. namespace UnityStandardAssets.ImageEffects

The image effect does work however, and throws no errors or warnings.