Specialized Lens Filters for Unique Lenses

For most people, camera lens filters are a round piece of glass that screw onto the front of the lens. But what if your lens is too long or wide, or you need to move the filter while shooting? There are several different options for these cases—ranging from relatively standard filters to highly specialized ones designed for specific lenses.

There are three main challenges with conventional screw-in filters: 

• Using them with fast, powerful telephoto lenses
• Using them with ultra wide-angle lenses with extremely large angles of view 
• Cases where screw-in filters fit but lack flexibility, requiring rectangular filters.

Solutions to these challenges may overlap, but let’s take it step by step. 

Filters for telephoto lenses 

The first challenge comes with powerful telephoto lenses, particularly those with fast apertures. The major issue is the large diameter of the front optical component. A conventional filter would need to be a huge, heavy, fragile, and expensive piece of glass. Additionally, using a polarizing filter would be impractical because it would be positioned far from the photographer on a long lens, making it difficult to rotate. 

This is why professional telephoto lenses have a slot near the bayonet for specialized drop-in filters.

This setup addresses size and usability concerns but requires specialized filters that aren’t interchangeable with other lenses.  

Interestingly, some adapters for different mounts also include a slot for rear filters. One well-known example is the Canon EF to RF adapter, which comes in three versions. One of them allows you to insert filters. Similarly, Breakthrough Photography makes an adapter for the PL mount to Canon RF, with an integrated filter slot. While these adapters limit lens selection to a different mount, they allow all filters to be used with any compatible lens. 

For drop-in filters, an external wheel is often included, allowing the photographer to rotate a polarizing filter hidden inside the lens.  

Issues with ultra wide-angle lenses

While telephoto lenses have a single solution, ultra wide-angle lenses require multiple approaches.  

The problem arises when the angle of view becomes so wide—typically 16mm or less (full-frame equivalent)—that a screw-in filter creates black edges in the image. 

That’s a minor issue compared to lenses with a convex front element, which makes screw-in filters impossible to attach.   

Rectangular filters

To address this, manufacturers like Cokin, Lee, or NiSi have developed systems for mounting rectangular filters in front of the lens. These glass filters are larger than the front element and are held in place by a filter holder that either screws into the filter thread or clips onto the lens externally. 

The holder expands outward to avoid obstructing the image, with slots positioned further from the optical center. For example, a lens with a 10cm front diameter can use 150mm-wide filters. These systems typically allow stacking multiple filters—for example, a polarizer, ND filter, and color filter. These types of filters are commonly known as slot-in filters. 

These systems aren’t just for problematic lenses—they offer greater versatility, allowing the use of rectangular filters, including graduated neutral-density filters. These filters darken the sky or other bright parts of the image. With the holder, the filter can be moved up or down as needed, something screw-in filters can’t do.

Rear filter holders

We move from relatively standard solutions to systems tailored to specific lenses. Some ultra-wide “glass” includes a rear filter holder near the bayonet, allowing you to insert gel or solid filters.  

These filters lack edges, meaning they can’t be adjusted once inserted. This rules out polarizing and variable ND filters, which require rotation. 

The most commonly used filters in this setup are plain ND filters, which darken the entire image for longer exposures.   

A drawback is that changing filters requires removing the lens from the camera body, and handling small filter sheets can be tricky, especially in dusty or windy conditions.  

However, gel filters provide a budget-friendly option, as photographers can cut them from inexpensive filter sheets/gels to change the colors of the lights.  

Some lenses come with a rear filter holder included. For example, the Sony 12-24/2.8 comes with a template to cut your own filters. For others, third-party manufacturers like Haida offer custom holders that replace the original rear component.  

Rear screw-in filters 

Another specialized option is rear screw-in filters, which attach in front of the bayonet, using a rear filter thread similar to those found on the front of the lens.  

This system is used on lenses like the Laowa 10-18/4.5-5.6 and Brightin Star 9/5.6, which use smaller (37mm or 34mm) filters that are significantly cheaper than the typical 77mm or 82mm professional diameters.

This system is an intermediate step between standard and specialized mounting. But even though unscrewing the filter sounds easier, it’s clear from online reviews that turning the filter tight around the bayonet is fiddly and cumbersome.

Filter or no filter? 

The systems I’ve described are useful for extreme focal lengths. However, some lenses simply aren’t designed for filters. In such cases it’s a trade-off—you may lose certain effects, but you gain a unique perspective that can be just as valuable. At the end of the day, photography is about making the most of the tools available at the moment.