I use the 77mm filter on my Canon EOS 6D with a standard 24..105mm lens. He fits there perfectly.

In the test photos, there was no visible difference on the camera screen from photos without a filter. The effect only became apparent in the details on the big screen. Otherwise very bright areas are reduced in intensity by the filter and sharp edges are also softened a little, but without the kitschy effect of a soft focus. If you take a closer look, the entire image is somewhat darkened, as if by a very fine gray haze. The differences are almost imperceptible in normal ambient light, but are visible on the screen in dim light.

I like that the filter gives you more atmospheric pictures, especially in dark surroundings with light sources in the picture (e.g. candle, lamp, moonlight on water, etc.), without having to post-process them heavily on the PC afterwards. The halo around the light sources is visibly emphasized without appearing artificial.

This diffusion filter is certainly not intended for everyday photos, but rather for special moods. Of course you can still edit the pictures on the PC, but the filter does some of the work when you take the picture and - as I said - doesn't look so artificial. Therefore, amateur photographers who like to work with atmospheric light should at least take a look at the K&F diffusion filter.