GX85 4K Video Recording Length Test

ronald weissman wrote:

There's been a fair amount of confusion about the Panasonic GX85's (North American version) maximum video recording length. Some have said that unlike the GX8 and GH4, the GX85's US version also enforces the EU's 29 minute limit. Others have indicated, from documentation, that this is not the case.

I tested this today with a freshly charged battery, a 128GB card and am happy to report that my 4K/24p session continued recording until the battery was exhausted. The battery lasted 1 hour 33 minutes (could probably have eked out another minute had I not used the battery for some setup and card reformatting prior to starting the video. File length was approximately 61GB. One caution in interpreting these results: rather than shoot variety of scenes and material, the camera was left on a tripod without varying scene content. It is possible that results may vary based on how different scenes are compressed and the impact (or not) that this might have on processor power draw or on storage size. But I'm fairly confident that you can count on 1.5 hours of continuous shooting before changing batteries.

This is the 1st confirmation I've seen the recording does not stop at 29min mark, as the other consumer cams in this class do. Good to know.

There exists an external power supply (see this thread: http://www.dpreview.com/forums/thread/4004484) which should provide even longer recording times. With a 128GB card, this ought to give you 3 hours. I haven't tested or heard reports about overheating beyond 1.5 hours, so, again, until this is tested, caution is advised.

Unfortunately the USB adapter only charges, does not supply power to the camera directly, nor does charging while the camera is being used,  thanks to Carey Rose who answered my questions and did the test:

http://www.dpreview.com/videos/1782536804/look-sharp-panasonic-lumix-dmc-gx85-gx80-video-preview?comment=1123944341

For comparison: The similarly sized Sony 6300 overheats with 4K easily and often well before the 29 minute limit has been reached. (I used the recently introduced Sony Play Memories App hack to extend all of my Sony cams to unlimited recording times, but the widely reported (and personally observed) 4K video overheating problem with the 6300 is an even more constraining issue than the EU's arbitrary 29 minute recording limit.) Luckily, Panasonic engineers, using similar frame rates on a similarly sized cam, have somehow managed to avoid the overheating problem. Kudos to them.

BostonC wrote:

Unfortunately the USB adapter only charges, does not supply power to the camera directly, nor does charging while the camera is being used, thanks to Carey Rose who answered my questions and did the test:

You are correct about the USB port - but external power is not via the USB port...

See page 308 of the GX80/85 manual - which mentions the "AC adaptor (optional)/DC coupler (optional)"... but unfortunately doesn't give the part numbers :-/

It is an AC to DC converter that feeds a "dummy battery". The two are connected by a wire that feeds through the "extra" little door in the battery compartment's "main" door.

The camera runs from the mains-powered dummy battery, the same way it runs from a regular battery. Panasonic frequently uses this method.

I've heard the Panasonic parts are DMW-AC8PP (power) and DMW-DCC11 (dummy battery), the same parts that are used by LX100, GX7 etc. There are 3rd-party alternatives that might be cheaper.

I can't personally verify that those parts are correct for the GX80/85 though - I dont have them myself and have never tried them.

I have put the following card

https://www.samsung.com/us/computing/memory-storage/memory-cards/microsdxc-evo-plus-memory-card-w--adapter-128gb--2017-model--mb-mc128ga-am/

According to the manual there should be no recording limit for this type of card but when I try to record I get the 29 minute. The camera is British GX-80