Even very basic DSLRs will happily offer 600 shots per charge of the battery, but many stretch into four figures. The very best DSLRs can rattle off almost 4000 frames per charge, although this is admittedly with considerably larger batteries.
Mirrorless cameras, however, fare far less impressively here, with around 350-400 frames per charge being the norm. Even professional models don't exceed this by any significant margin. But why is this?
First, mirrorless cameras are inherently more dependent on battery than DSLRs. Their LCD screens are typically on at all times, and when they’re not it’s the electronic viewfinders that are, and both of these need plenty of power. By contrast, optical viewfinders only need a modest amount for the various LED displays and overlays.
Furthermore, the fact that most manufacturers try to make mirrorless models as small as possible means that their batteries are also small, which also presents a limit on their capacity. Many mirrorless cameras also have image stabilisation built into their bodies, which further degrades battery life (although you’ll also notice battery life to be less impressive when using lens-based image stabilisation on either DSLR or mirrorless cameras).
Of course, you can buy spare batteries for cameras in both camps, so whether this is as great an issue or not is debatable. One advantage of mirrorless cameras, however, is that many now offer charging through their USB ports, which is very convenient when travelling.