Hi all. I've been dipping my little toe into the waters of digital. I borrowed an EOS 40D and put my trusty 85/1.8 on it, and have been trying things out handheld and on my tripod. I now have some jpegs and some .CR2's loaded on my laptop and a trial copy of Bibble with which to open and view them.
One of the many things that I am very confused about is when people at various digital photography blogs and review sites put up a 100% crop as an illustration of some comparison or technical point, and then say "if printed at this size the print would be five feet across." So, I tried figuring out the math for my own camera and laptop screen and come up with the following: sensor 3888 X 2592 pixels; display res 1680 X 1050 pixels, diagonal size 15.4", 129 ppi. Dividing each of 3888 and 2592 sensor pixels by 129 display ppi would give me a printed image of only 30" by 20", a far cry from "five feet across."
Am I missing something with an imperfect understanding of the terminology or the math, or are the bloggers/reviewers using displays with much less resolution than my laptop screen has?