why does the 1d have less megapixels than 5d

[josephruggieri]

Can anyone tell my why Canon's flagship camera always has less megapixels than the next tier lower?  I.E - the current 1DX has 18.1 MPS, and the 5DIII has 22.3?

[cicopo]

Megapixels aren't the only consideration even though we allways seem to want more. In previous 1Ds series bodies (which were full frame) the frame rate (FPS) was considerably lower than the 1Dx which can shoot 12 FPS. That's going to produce an awful lot of data to hold in the buffer while simultanously transferring some to the cards. That improvement is very valuable to a lot of users, especially since it also has a superb AF system. If you had to shoot fast paced action as a pro you'd appreciate the compromise re more pixels for the better frame rate from a FF body that can nail the shot. I'd also guess that having  fewer photosites (on the sensor) allows them to be bigger which gives a better signal to noise ratio for cleaner high ISO shots.

[rddelliott]

  The lower megapixel count on the 1Dx wa probably a compromise between frames per second and resolution as explained by cicopo.  18 mp in the right hands is enough to produce stunning 24X36 prints.

[ScottyP]

Agreeing with what Cioppo said.

Note that Nikon's big flagship camera, the D4, only has 16.1 mp.

Jamming too many photosites onto at sensor creates noise problems, but unfortunately the public sees MP as a quick reference number to judge one camera vs. another.  Like "horsepower" on a car, or something.

I think Canon's marketing needs to come up with a simple-sounding metric for signal to noise ratio or maximum high-quality ISO and start plastering it all over its advertizing and its camera boxes.  Just keep it simple, so John O. Public will sieze on it like they currently do with megapixels.