The same in final 3200x2400 rendered to disc (1h rendering time), then reduced (bilinear) to 800x600, then saved .jpg with 5% compression. It seems nearly the same, but you can see that the shadows are somewhat grainy below the metal sphere. Should mention that it was done in Vue2.1. Conclusion : you can save time, using this tip, but you can loose quality if some options are used (soft lights for example). What's your opinion ?