With in inside scene, you have a lots of indirect lighting. In this case I would recommend either Studio with Luxrender via Luxus or the use of Carrara, that can handle indirect lighting very well.

If you once set up your lighting inside your scene, there is no need to adjust it when you move the camera.

The opaque beam you mentioned is a light effect, like god rays or fog. This is kind of light source is refracting the light from the genuine light source, and also it deceases the ammount of light that reaches the aim.

I strongly recommend the book "Lighting & Rendering" by Jeremy Birn. You get very much of fundamental and special information there.

I hope, I was able to help a bit.

Eddy

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