Quote Originally Posted by Oren Grad View Post
Commonly accepted definitions base large format photography on 4"x5" and larger sheet film (or the 9x12 cm metric equivalent), regardless of the style of camera being used. This is the definition we will use. We would also consider a digital back with a nominal sensor size of 4"x5" or larger to be LF, as well, regardless of technology.

This is our current definition. As far as Forum policy is concerned, it supersedes anything that was posted previously in this thread.
That is exactly how Wikipedia sees it. Most interesting from the OP: there not a specific reference to a camera or a film format. From there it wandered from apples to pears.