It can soften the entire image, reduce the contrast of the highlights, and produce a halo, making the image soft. 

I use one on a Pentax 24-70mm filter size 82mm. Just make sure you buy the right size for your lens. I have the nd1000, and I am very happy with result. They also sell adaptor step down for your other lens. 

Black soft filters can be used to reduce blemishes and wrinkles in people or objects by reducing the resolution of the image. They can also be used to increase contrast and create a halo or glow effect for specular light sources in a scene. 1. soften the light effect of the actress's facial details, 2. It can effectively reduce some wrinkles and spots on the face of the actor, but at the same time maintain the details and clarity of the character's hair and eyes. 3. It also plays an important role in film shooting. Excellent black mist filter does not affect the color temperature, the use of dim scenes with a hazy age will create the atmosphere of the scene well. 

Hi, the K&F black soft filter 1/4 has the same effect as Tiffen black pro-mist filter 1/4, just difference in name , thanks. 

Yes , this filter support to add other filter on it , such as Tiffen black pro-mist filter , or KF black soft filter , thanks.