Camera Filter Choices: Square Or Circular?

When choosing camera filters, deciding between a square filter system and those that screw onto a lens can be tricky as both types have pro points the other doesn't. So, which should you invest in? Let's take a look at how each type works so you can make a more informative decision. 

Screw-in Filters

These round filters are really easy to use as they simply screw onto the end of a lens but you do need to make sure you purchase the right filter thread size for the lens you are using. Of course, this does mean you may need several filters in different sizes if you own a variety of lenses or you can purchase one filter in a particular thread size and use step up rings to fit the filter to the other lenses in your collection.

This type of design is useful for filters you'll fit and not remove, such as UV filters which you may use to protect your lens from scratches etc. This design's also suited to polarising filters as you rotate these filters in a supplied mount to increase / decrease the effect. Normal ND filters also work well in this format but if you need to work with a ND Grad, you'll be better off reaching for a square filter format as this system allows you to adjust the filter's vertical position, something you'll find yourself often doing when working with ND Grads. 

• Easy to use and set-up
• Convenient to store and transport
• Step-up rings mean the same filter can be used on different sized lenses 
• Good for UV, polarising and other effects which cover the entire filter, i.e. warming filters 

Square Filter System 

With a square filter system, there are various systems and sizes to choose from. The Cokin Creative Filter System is an example of a square filter system and it consists of three main components: filter holder, adapter ring and a filter, of which there are 4 different sizes to choose from. Square filter systems allow the user to quickly change what filter they're using on their lens and as mentioned, ND Grads are particularly well suited for this type of filter system. 

Another advantage of this type of filter system is that multiple filters can be used together without vignetting. However, when not using multiple filters, ensure you place the one filter you are using, particularly when it's an ND Grad, in the slot closest to the lens. 

• Need an adapter but once in place filters can easily be added / removed
• Can use multiple filters without worrying about vignetting
• Good for combining filters to create effects and where the user needs to adjust the position of the filter such as when using ND Grads.