Although many filters are no longer required with digital photography, thanks to the power of applications like Lightroom, Capture One and Luminar, there are some that can still be very useful. Particularly neutral density filters. But filters that go onto the end of your lens can be a pain, especially when it comes to keeping them clean. California-based Aurora, though, has developed a drop-in filter solution for mirrorless camera lens adapters that not only keeps the filter clean and protected but also means you don’t have to swap it out when changing lenses. They kicked off recently on Kickstarter, and have already more than doubled their goal.

The Aurora Aperture Adapter Mount Format Filters Kickstarter page begins with the line “One set of filters for every lens”, which is a great idea. The fewer filters we need to own, the less space it’ll take up in our bags and the less money it costs us to acquire them. You can, of course, do that now, using step-up rings with round filters or by using some kind of square format filter system like Lee or Cokin. But if you’re regularly swapping out lenses, regularly unscrewing the filters off one lens to put them onto another is a hassle, and increases the chances of getting sticky fingerprints on your filter, leading to more wasted time cleaning them. If you shoot mirrorless cameras using adapted lenses, however, Aurora’s new system sits inside the adapter, meaning it’s available to all lenses of the same mount, without having to swap it out to each new lens, and it’s protected from dust and fingerprints out in the field. At the moment, the filters listed are for four different mount adapters…

Canon EF-RF Mount AdapterNikon FTZ Mount AdapterSigma MC-11 EF-E Canon to Sony E Mount AdapterSigma MC-21 EF-L Canon to L Mount Adapter

And there are also four different filter types…

PowerUV sensor protector filterPowerND neutral density filter (2, 4, 6, 8, 12, 16 stops)PowerGND graduated neutral density filter (1.5, 2.5, 3.5 stops)PowerDusk light pollution reduction filter

Now, normally I’m not a huge fan of UV filters for “protection”, but I think here it makes a lot more sense than having a filter on the end of your lens. Many of Sigma’s Foveon sensor cameras contain a similar type of removable filter within the camera body itself, which helps to keep dust off the sensor. The Blackmagic Pocket 4K, too, has a glass cover over the sensor. Sure, they’ll still build up dust, but it’s a lot easier and less risky to clean those than it is to clean the sensor itself. I’m not sure how useful the PowerGND filters will be vs typical square format ND grads, given that you can’t move the filter to adjust it to your horizon. I would expect, however, that the PowerND filters would prove to be the most useful. 2, 4, 6 stops are ideal for video, and 8, 12, 16 stops should work great for long exposure photography. The PowerDusk sounds interesting, but I’d like to see it in person before making any type of judgement.

Not that it should be needed, for the most part, but Aurora states that these drop-in filters feature the same PFPE nano-coatings to repel water, oil, dust and dirt. But it does mean that should you need to swap out filters in the field, it will help to prevent anything getting onto the filter during the short time it’s exposed. Of course, whenever you want to swap out the filter itself, you’ll still be exposing the sensor, however swapping out a filter for a different one appears to be quite quick and easy according to the campaign videos. And you’d be exposing the sensor anyway when swapping lenses if not using such a filter. To back the project and claim your own, pledges start at only $44 for a single filter. Delivery is estimated for October 2019.