The pros and cons of drop-in filters for mirrorless

In order to use EF lenses (for more options take a look at our Best Canon EF lenses to purchase guide) with the Canon R-series bodies, it’s required to utilize an EF-EOS R adapter. While there are third-party choices readily available such as the Viltrox EF-EOS R Auto Focus Mount Adapter, Canon uses 3


EF-EOS R adapters and among them includes a drop-in filter. There were just three suitable filters on deal from Canon (clear, polariser and variable neutral density), so it wasn’t until a few other companies began using a range of compatible drop-in filters that it actually got my attention.
Dunstanburgh Castle, Northumberland sunset
Dunstanburgh Castle, Northumberland. Canon EOS R5, Canon EF 11-24mm f/4L, 2 secs at f/16, ISO 100, tripod, Kolari 3-stop ND drop-filter used to accomplish 2-second exposure time

I don’t use graduated filters, so currently they are all 82mm Heliopan glass screw-in filters (with a stepping ring to fit lenses with 77mm threads). It’s easy to cross the threads or worse, drop the filter!

Stacking filters can likewise lead to vignetting when utilizing wide-angle lenses. It seemed to me that a drop-in filter system could eliminate the majority of these issues while also supplying a number of other advantages.

The main advantage

Possibly the most significant advantage and the main reason for me buying the Canon EOS R5 is that the drop-in filter adapter lastly allows me to very easily utilize neutral-density filters with ultra-wideangle lenses like Canon’s EF 11-24mm f/4L USM and EF 8-15mm f/4L fisheye USM. Formerly, making use of filters with these lenses had only been possible with either really fiddly or cumbersome solutions. Canon UK, Breakthrough Photography and Kolari kindly sent me a number of samples of their drop-in filters to evaluate with my Canon EOS R5.

A filter of some sort has to remain in the adapter as it forms part of the optical path and is required for the focusing to work properly. Currently I’m using Canon’s own clear filter and also its polariser.
using drop-in filters

Inserting Breakthrough Filters’ 10-stop ND into Canon EF-EOS R adapter on EOS R5 with Canon EF 11-24mm f4L attached

Drop-in VND
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I’ve never been a fan of variable neutral-density filters (VNDs). In theory they sound terrific, however in reality, due to the way they work, I have never ever been able to guarantee an even result across the frame. However, the drop-in VND from Breakthrough Filters is by far the very best I have actually utilized to date. I believe potentially due to its smaller size and its position at the back of the lens, any uneven impact is reduced.

Care has to be taken when to utilize it and with which lenses, but excellent results correspond enough for me to confidently use it on a regular basis.

Among the excellent things about the 1.5-11 stop VND filter is that you can use it to shoot a bracketed set of direct exposures without altering the electronic camera settings– very useful if shooting long exposures with moving water, as each exposure will show a very comparable water effect, making it much easier to blend exposures seamlessly in software.

This is a strategy I have used frequently in the past, but it’s hard when you have to screw standard filters on and off the front of the lens without moving anything!


I store my drop-in filters in a little pouch on my belt, so they’re always quickly accessible. They can be ‘slotted-in’ even more quickly than screwing a traditional filter onto the front of the lens.

I can now use 2 filters without vignetting when using lenses as broad as 16mm (one drop-in and one screw-on). An advantage over alternative body-mounted clip-in filter systems is that filters can be included without eliminating the lens, minimising the chances of moisture and dust triggering problems.

Drop-in filters have actually significantly sped up my workflow in the field and have actually already enabled me to achieve images with severe wideangle lenses that were previously difficult.


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