Originally posted by littledrawe I'm going to need to see some kind of drawing or something to make this make sense, I suppose I am more of a visual learner. Off to the internets to see what I discover.
Imagine comparing the 12MP K-r and the 12MP Q camera. They both have the same size images that they output, the same number of pixels. But the Q has a much smaller sensor. Each pixel is a little node on the sensor that detects light, which means that on the Q they must be smaller and packet closer together. Otherwise you can't get the 12MP onto a smaller area. The second part is that lenses have a certain resolution of their output. If he camera sensor has the same resolution, it will be optimally sharp. But if the sensor has a higher resolution than the lens, the lens will appear to be not sharp, because the sensor is detecting more fine detail than the lens can deliver. So a lens that looks sharp on the K-r, might look less sharp on the Q. But it might look perfect on a 6MP APS-C camera.
Same principle for medium format lenses. Btw, the D800e, with its high MP count, is facing this problem because a lot of lenses that were perfectly decent on older models now no longer look as good on this camera. So if you make a sensor with much higher resolution, you also need to make lenses that match it.