Thanks for all the info. I appreciate it. At the moment Im rendering (on my desktop system, Im writing this on my old powerbook) a night-time scene. I added two other landing plateforms and a couple of lamp posts on the ground between the plateforms. On this attempt the only lights used are the ones actually in the scene, all the little lights on the plateforms etc. But afterwards i will play around with some lights using your suggestions. Cheers, H&B