>>3083300It takes the total amount of light from a 35mm FF lens, and compresses it down to the size of an apsc sensor, which lets the sensor see what a FF sensor is supposed to see
Since you compress the light to a smaller area, it also allows it to act like a faster lens, and you don't lose any detailed compared to the crop factor if you use a decent enough sensor/adapter
Good for vintage lenses on the a6000, like the Pentax 50mm 1.4
It essentially turns it into a 50mm 1.0 that gives the full focal length on the smaller sensor
