At ISO 12800 the Panasonic GH4 Image is completely useless however at the same ISO Panasonic GX8 is able to restore bit more details. ISO 25600 test images doesn’t deserve any comment from my side however the image sample capture by GH4 camera is more worst than the GX8. So if you are serious about the image quality you must buy the
Panasonic GX8 camera.
Buy Panasonic GX8 camera from Amazon.