Here is a short video with both cameras mounted side by side on tripods.
Both cameras shot at their best settings for the exact same scenes, although the Sony has a wider angle than the Panasonic. The "best" settings for each:
A500 - 4K, 30p, wide, digital stabilization off. Bitrate is 72Mbps.
AS15 - 108060p, 170 degrees, digital stabilization off. The bitrate is 28Mbps, just like camcorders like the good Panasonic TM900 for 108060p
The combined video was rendered to 108030p (XAVC S). So, you are seeing both at 1080.
*For each scene, the Sony is first.*
Conclusion: The Sony at 1080 has lower resolution, more CA and more noise than the Panasonic 4K video rendered to 1080
. The Sony coloring is also too blue. Audio seems comparable. The Sony video is actually pretty awful, worse than most HD camcorders. The Zeiss lens is a disgrace (CA is terrible). Maybe in the new model (AS100) there is great improvement.*
Interestingly, both cameras have the same size sensor (1/2.3"), and the same aperture lens (f2.8). The Sony has more (unnecessary) pixels, so perhaps that is why the video is much noisier.
The video: https://vimeo.com/100859195
Sony video frame grab:
Panasonic frame grab:
*Note: the new AS100 has similar internal hardware specs as the AS15: the same Zeiss Tessar f2.8 lens, the same 1/2.3" sensor but with even more pixels!. The codec is different, however, and the max bitrate is higher.