Comment Re:39 megapixels is very common w/pro gear (Score 1) 103
And to get everything in focus at that level of detail you need a _very_ flat subject, or to have everything you want at the infinity focus level.
The depth of field (area that is in acceptable focus) decreases as required detail goes up, not to mention that if you up the required detail enough you wind up being forced to use a larger aperture otherwise diffraction effects will be the limiting factor.. using a larger aperture decreases the depth of field even more.
There are real practical limits for getting serious detail, unless your subject is completely flat and/or it's all at infinity focus.
It's the same problem large format photographers have had for ages, a surplus of detail at the sensor (film) level, but never enough depth of field to use it all.