Depth of Field and Megapixels
See also Depth of Field.
Sometimes it’s worth reminding ourselves how little megapixels matter with some subjects—limited depth of field can eliminate nearly all of the potential resolution of an image. This example was shot with the Canon EOS 5D-IR (infrared conversion) using the EF 100-400/f4.5-5.6L IS USM at f11. Color as opposed to infrared would make little difference.
Even at this greatly-reduced size, the foreground and background blur can be seen—and this is at f11! Results are worse at f16 due to diffraction (I tried both apertures).
Below is an actual-pixels crop. Only a very narrow band of the entire frame is actually in acceptably sharp focus, no more than 300 pixels (out of 2912), probably no more than a 100 pixel band is at peak sharpness.
A 6-megapixel camera (instead of 12) wouldn’t produce an appreciably different result outside a narrow zone, something to keep in mind when considering megapixels.