jeljohns wrote in post #15307801
Because I don't know. I don't enter any information, I just export at the size the file was when I imported from the camera, with the exception that it is now a jpeg and I leave it at 100% quality. This is where I'm confused because I didn't know you had to enter pixel dimensions in lightroom to export
You don't have to. Read again what I wrote:
If the answers to the above questions are negative - you are not cropping in LR and the Resize box is not ticked, then you are sending a 3744 x 5616 pixels image, more than enough for a 12x18 inch print at 300 ppi.
OK, so you are sending them a 3744x5616 pixels image (you really ought to read enough of the manual to know what size images your camera produces) and ordering an 8x10 print. This is a real resolution of 468 ppi, not the 240 ppi that the lab said they received; so, as Moppie suggested, the problem seems to be that your file is carrying a 240 ppi tag which is confusing the ROES. In the LR Export dialog page, do not check the Resize box, but do change the Resolution number to 300 ppi (the same advice Jay gave three days ago) and this will give your file a number that will make the lab happy.