For offset litho/printng press type of work 300dpi at actual size is essential. For large format inkjets used in trade show backwalls or posters, typically 150dpi at actual size is satisfactory. For hi resolution desktop printers (ex. Epson Photo 2200) 200dpi at actual size. If you are working with other sizing software like Genuine Fractals or us Photoshop to up-size the image after rendering you can get away with half of the dpi's I mention above. However, there will be a little fuzziness and loss of clairity in the process. Also, Photoshop works best when the increase in size follows even increases like 200% or 400%. Increasing size to 400% would really be pushing your luck though. Size increases like 160% creates noticible pixilation. For Hi dpi renderings, make sure that you don't have Carrara doing any unnescessary calculations. Turn light rays down do 4 unless you have transperency that has more than for sides to penetrate and eliminate options like Refraction if you don't need it. Mark