Some applications and rendering systems have lens shaders which will allow you to recreate all kinds of lens effects when rendering. Others offer a post-rendering effect that can simulate lens effects and some distortions.

A quick way to literally distort the room around you

What if you wanted to simulate a Fisheye lens in C4D, without the camera lens?

Here, Konstantin Magnus comes up with a clever solution that isn’t really an effect of the camera at all. Konstantin uses the spherical deformer on the object itself. Linking the deformer to the camera can have the effect that the deformation is actually a part of the camera lens.

Konstantin notes that you can have more artistic control by using the falloff settings on the deformer. You can also activate the physical renderer and set your camera -> physical -> lens distortion to about 10% to do it properly.