When you can’t use a physical filter, such as an ND grad, then trying to emulate them in Lightroom is the only solution. Here I’m going to show you how easy it can be when using an Adjustment Brush but point out the pitfalls that can occur if you choose to use the Auto Mask function, writes Andrew James. That’s not to say that you shouldn’t use it because actually it can be rather good. It’s just important to be aware of where it can potentially degrade image quality and leave unsightly and obvious marks.