Look at this image:

I want that only the background (the wall at the back) will be blured.
but when I am rendering, the celinder is being blured too:

how can I do that only the back wall will be blured???
- this is for animation! so I cant use photoshop.

I want that only the background (the wall at the back) will be blured.
but when I am rendering, the celinder is being blured too:

how can I do that only the back wall will be blured???
- this is for animation! so I cant use photoshop.