I've been shooting with an NEX 7 for about a year now and have come up against the overheating issue several times. The latest was just the other day where it overheated in just 30 minutes of short clip shooting.

Has anyone experienced any overheating issues with any of the A7 line? If so, can you compare it with the NEX 7 or other NEX cameras? Is it better or worse? Thanks! Joe

Seems to be a problem with the A7 in video mode..
Re: Sony A7 overheating in video mode: Sony Alpha/NEX E-mount Talk Forum: Digital Photography Review (http://www.dpreview.com/forums/post/53263922)

No problem with A7s.

I was fortunate enough to own a NEX 5N that had no overheating issues. I repeated 30 min continuous shooting 5 times in a row and although the over heating symbol showed up on screen it never actually switched off. Never used it for that long on a job though as I have professional camcorders.

I think it's hit and miss ?? some one should really release a firmware hack for the older NEX versions by passing the auto shutdown with a "use at your own risk" attached.

My A7S arrived over the weekend and I was able to test it out. I took 6 consecutive 29:49 clips at ~93° and I didn't get the overheating icon. It went through two fully charged batteries and half the charge of a third. I also used an infrared thermometer to check the temperature and the hottest was behind the screen and the bottom of the body both at 105°.

I was shooting XAVC 1080p60 to a PNY 128GB SDXC card in fairly low light, 1/60 shutter and accompanying high ISO if that matters.

I've filmed extensively with my A7S and have yet to have any issues with overheating.

Whilst this isn't about an A7, I own a Sony A6000 which I use as a B-camera and have found that overheating is very dependent on the ambient temperature. I can comfortably shoot 29 minutes of footage at room temperature of 18-20 degrees C, but in the summer I was shooting in a small room on a hot day with three redhead lights and overheating certainly became an issue.

Each take became shorter and shorter before the temperature warning symbol appeared and I had to swap to my Nikon D800.

How long will the A7s go when recording externally before shutting off or overheating?
What kind of battery pack do you recommend?

I often use my GH4 for 1-3 hours unattended with just the camera battery and internal card, but I am interested in shooting wider, in lower light, and at 120fps.

It won't shut down from overheating, or stop outputting when running to an external device. I've done it in excess of an hour (which is about the limit for a single battery in these conditions.) That said, I've never tried 10 hours of external output. YMMV.