When trying to print to a jpg file, in order to send it to a printing service, why are you obliged to set up a page size trough printer paper size? You should be allowed to freely set up the page size, without beingforced to chose a printer.
In my case, as i wanted to print a large size (50 x 70 cm), I was obliged to use a pdf printer, that allowed to set up the page size. In this case, it resulted that the aspect ratio of the photo to be printed differs from the original file (actually longer). I think that this may be due to the printer driver.
Yes the print size depends on the printer's driver.
If printer support the page size you will be able to choose it.
Gracias, it was a silly mistake.