Last year, Sony introduced a 4K camera for under $1,000. In 2016, the price point is staying put, but the sensor and lens sees big improvements for the manufacturers 4K prosumer model.
The Sony AX53 uses a 1/2.5" backlit sensor. That's slightly larger than the older AX33's 1/2.3", but that's not where the biggest change is. The AX33 used a 4:3 aspect ratio that didn't use the entire sensor. Sony says the new AX53 uses the entire sensor with a 16:9 aspect ratio. Because the size of the sensor increases while the megapixels don't increase, the AX53 should perform a bit better in low light.
Taking just one glance at the tech specs shows Sony also updated the lens--the optical zoom is doubled to 20x on the AX53. Sony also adjusted the design to make the lens more compact and improved the autofocus speed as well. Sound should see a bit of an improvement with a new five-direction mic as well.
The AX53 also includes Sony's Balanced Optical Steady Shot, which is a nice five-axis stabilization system. As a prosumer option, it also features both automated and manual modes.
Despite the advanced features, the Sony AX53 comes in a familiar consumer camcorder body style. The entire camera weighs 22.4 oz., about two ounces lighter than the older AX33.
The Sony AX53 looks like a good option, though the category is becoming increasingly competitive, so be sure to check out other 4K camcorders before you buy.