There a lot of info on the nex5n so I won't go into it. It's a great little camera. Totally capable of making fantastic looking video.
The a57 has less info out there. Here are 3 negatives that would make me choose the nex5n even with overheating issues.
You can not use auto focus and still have control of aperture and shutter speed. Many cameras share that trait but it's something to consider.
Tracking focus doesn't really work all that well. I found it to be useless while others claim the opposite. I thought focus popped in and out way to much to make it useful.
Live view on an external monitor is small. The way Sony adds the info at the bottom of the picture makes the screen really tiny. A 7 inch monitor turns into a 5 inch. If you have a 5 inch monitor you might as well use the LCD on the camera. ( Guessing at sizes. Didn't actually measure but it's sizeable.)
I also didn't like the LCD on the camera. It looks good but doesn't really flip out in a useful way.
A real filmmaker won't be bothered by the first two issues because they will pull focus. I thought these could be a deal breaker to some. Hope it helps.
The a57 has less info out there. Here are 3 negatives that would make me choose the nex5n even with overheating issues.
You can not use auto focus and still have control of aperture and shutter speed. Many cameras share that trait but it's something to consider.
Tracking focus doesn't really work all that well. I found it to be useless while others claim the opposite. I thought focus popped in and out way to much to make it useful.
Live view on an external monitor is small. The way Sony adds the info at the bottom of the picture makes the screen really tiny. A 7 inch monitor turns into a 5 inch. If you have a 5 inch monitor you might as well use the LCD on the camera. ( Guessing at sizes. Didn't actually measure but it's sizeable.)
I also didn't like the LCD on the camera. It looks good but doesn't really flip out in a useful way.
A real filmmaker won't be bothered by the first two issues because they will pull focus. I thought these could be a deal breaker to some. Hope it helps.