My photo printer prints at 300 dpi, as do most domestic models. No matter what density of image that I throw at it, it still prints at 300 dpi. I understand that for top quality the image density should match the print density. My original dslr is a Nikon D70; a 6 mp sensor; 3008 x 2000 pixels. At 300dpi thats 254.7 mm x 169.3 mm. Printed on an A4 sheet gives borders of 21.2 mm and 20.3 mm. My D90 produces similar proportions on A3. I am not going to upgrade.