Camera skills How to work with a square filter system

Using one of these two-part holders will make it easy to add and remove filters as you shoot

Mounting ring

You’ll first need to screw a mounting ring onto the filter thread of the lens; you may need more than one of these if you have lenses in different sizes. Dedicated rings for wide-angle lenses are also available.

Filter holder

This clips onto the mounting ring and typically has two or three slots for holding square or rectangular filters. You may need to buy an additional attachment if you want to add a circular polarising filter to your setup.

Square filters

You can use glass or resin filters. They don’t have to be from the same brand as the holder: they just have to be the correct size. The holder can be unclipped with filters in place, making it easy to compose and focus between shots.

Filter slots

Strong ND filters, such as the Lee Filters Big Stopper shown here, have a foam gasket that presses against the filter holder and prevents stray light seeping in. Always use the slot nearest the lens for this type of filter.