Shadowblade wrote in post #17610858
You save a lot of thickness throughout the body by not having a mirror assembly. And an EVF takes up much less space than a pentaprism, since it's essentially just a small OLED panel. Not to mention the weight savings (glass prisms and mirror assemblies are heavy, whereas EVFs are not). Which leaves a lot of space for extra battery power.
EVF, I agree it take less space than penta-prism. But mirror box, well yes for older mirrorless, but for A7R2 it's arguable. Maybe less thick, but I doubt by much, unless you would argue that Sony IBIS take zero space. I would love it too if a company can make image stabilizer out of thin air.
Can Sony make their camera bigger, yes. And I'm sure Canon can make their camera smaller too. I don't think Canon 5D series is pack light w/ circuitry. But yes, mirrorbox is a dead space that can't be occupied by anything else. But I believe Canon decided to make their xD(read 1D, 5D, 6D, 7D) series a certain size for ergonomic reason and not technical reason. Comparing 5D3 vs 7D2 which is FF vs 1.6x crop, you can see that they are about the same size and there is no reason why a crop body would take about the same space as FF body.