Why Use a Square Filter System For Your Camera?

A square filters system is the go-to option for many photographers and videographers that use an expansive collection of gear. Square filters work across multiple lenses, are compatible with larger thread sizes, and offer greater flexibility and control when working with graduated ND filters.

Here is an in-depth look at the reasons to consider a square filter system, as well as some limitations to consider before purchasing one.

The most convincing reason to buy a square filter is the flexibility they provide. Unlike circular filters, which screw onto the front of your lens and therefore need to match your lens’ thread size, square filters slide into a square filter holder that can be attached to the front of almost any lens.

Say you have three lenses, with a 39mm thread size, a 77mm thread size and a 95mm thread size respectively. And say you wanted to buy an ND4 for shooting in low light, an ND32 for shooting in mid light and an ND128 for shooting in bright light. To use any of those NDs with any of your lenses, you would need to purchase each ND at each thread size, totalling nine circular filters. But with a square filter system where each filter measures 100mm x 100mm wide and slides over the front of any lens, you would only need to purchase one of each ND, to be used on all three lenses. Although you’ll also need to purchase a square filter holder with three adapters, this is still a better option than buying nine filters made of premium optical glass.

For professional photographers who have multiple lenses with different thread sizes, square filters are a cost-effective way of meeting your filter needs with fewer products. If you already have a large collection of lenses, or you’re planning on growing your collection in the near future, opting for a square filter rather than individual circular filters for each lens could save you a lot of money down the track.

Another reason to consider investing in square filters is because they’re compatible with larger lenses. Some makers of circular filters will only create filters up to a certain thread size, such as 82mm. But if you planned to purchase a lens with a 95mm thread size, you may find it more difficult to track down a premium circular lens filter. Because square filters are commonly produced at 100mm x 100mm wide, there are very few lenses that are too large for a square filter system.

Even if you only carry lenses with small thread sizes now, it’s worth considering the larger and more versatile square filters now so you can peruse new lenses knowing your existing filter collection will accommodate them.

Square filters are also invaluable for photographers who use graduated ND filters, because they allow for an adjustable position of the filter. To understand why this is so important, we’ll run through a quick explanation of what a graduated ND filter does.

A graduated ND filter is similar to a standard ND filter, except that instead of having a consistent dark coating across the entire lens, it fades from a full ND coating to no coating. So when you’re shooting a landscape of a mountain range where the foreground is quite dark but the sky-filled background is bright, you can line up the graduated neutral density filter to only apply the light reduction to the bright half of the image, which will give you a more balanced image.

The problem with circular graduated ND filters, is that they fade from coating to no coating in the middle of the filter, and this position can’t be adjusted up or down. Using the example of the landscape photo with a dark foreground and bright background, you would need to line up the top of the mountain range in the middle of the frame. But with a square graduated ND filter in a square filter holder, the filter can easily slide up or down depending on where you want to apply the ND effect, giving you much greater control over the final image.

Where versatility is concerned, square filters beat circular filters any day of the week. So if you’re a professional photographer/videographer needing multiple filter strengths in multiple thread sizes, square filters will be the most cost-effective way to go. With that in mind, square filter holders are intricate pieces of equipment, and therefore come with a significant price tag. So if you only have two lenses and you want to play around with an ND32 on both of them, you’d be better off opting for circular filters.

Another drawback of square filters is that they can be heavier than circular filters on the front of your camera, given their larger size. This isn’t great if you’re a travel photographer and rely on a light setup to capture quick, candid shots and get from one place to the next. Square filters are better suited to landscape photographers or studio photographers who will have their camera set up on a tripod. They’re also suitable for videographers who carry heavy camera bodies and won’t notice a bit of extra weight. Our advice is to think about the situations you’ll be needing your filters for, and decide on a square or circular filter accordingly.