Go into Photoshop. Find out what the image size you are after is in pixels at 300 dpi. Then go inside Carrara/render/output and enter the pixels you got from Photoshop. Keep the resolution inside Carrara at 72 dpi and then select keep proportions. Pixel aspect ratio remains at 1. Then render. The output image will be a very large 72 dpi image. Open it in Photoshop and set the inches to what you are after and then set it to 300 dpi. This method produces wonderful sharp images ready for print after you convert to CMYK of course. It works without fail everytime. No need for any extra confusion or effort. Good Luck, steama