Originally posted by RussellW ie: 8 x 12 is fine however 8 x 10 is a cropped verison.
how about the other sizes?
It is all about aspect ratio
Aspect ratio (image) - Wikipedia, the free encyclopedia
A Pentax DSLR (like most other SLR) take images with an aspect ratio of 3:2, like 3000 x 2000 pixels (for a 6 MPixel camera), or 4500 x 3000 (for a 14.5 MPixel camera).
If the printing paper has the same aspect ratio, then no cropping will take place.
8 x 12 inch has an 3:2 aspect ratio as well (12/8 = 3/2). So, no cropping.
For other sizes, you now know the answer as well.