Briefly For years now, Sony's been iterating its mirrorless line of cameras one tiny tweak at a time. That continues today with the A5100, a minor variation on the company's existing line.
The A5100 replaces the NEX-5T, Sony's current midrange mirrorless shooter. It's the last of the Sony NEX cameras, which will all simply be part of the Alpha line from now on. It's also a very minor upgrade over the existing A5000. It inherits that camera's body design, but adds the more advanced image sensor from the A6000. The A5000 is a teeny tiny little guy — the smallest APS-C interchangeable-lens camera out there — but before this upgrade it didn't have the snappy hybrid autofocus system that's being used by many cameras these days. That changes now because the A5100 gets the 24.3-megapixel APS-C sensor with combined phase and contrast autofocus detection.
If it feels like all of these Sony mirrorless cameras are starting to blend together a bit, you're right. Sony's A6000 was a great camera for the money, and you can expect similar performance in a smaller body now. Sony's mirrorless cameras have always been solid. There's nothing new about that.
It's especially good when you think that the interchangeable lens camera will only cost you $899 when it hits Australian store shelves in September.