Various 4K video comparison test shots from the Panasonic DMC-FZ1000 4K QFHD/HD and the Lumix GH4. The Panasonic LUMIX DMC-GH4 films at 4K (Cinema 4K: 4096×2160 / 24 fps and QFHD 4K: 3840×2160 / up to 30 fps) video recording in MOV/MP4, or ultra high bitrate video recording at 200 Mbps (ALL-Intra) or 100 Mbps (IPB) without a recording time limit.
The Lumix DMC-FZ1000 combines 4K video recording capability (QFHD 4K: 3840 x 2160, 30 fps in MP4) with the ability to switch easily between video and still capture for the ultimate in image creativity. The FZ1000 also enables in-camera playback screen grabs of (3840 x 2160) 8-megapixel equivalent hybrid photography photos from 4K video footage to capture the spur-of-the-moment shots often missed with ordinary still photos.
Both Panasonic cameras recommend using UHS Speed Class 3 (U3) SD cards with a minimum write speed of 30MB/s, such as the Transcend 64 GB High Speed 10 UHS-3 here, to accommodate the resource-demanding needs of 4K video.
You can find the Lumix FZ1000 at a good price here.
The Panasonic Lumix GH4 can be bought for a low price here.