By site editor Dan Chung:
Jeromy Young from Atomos has posted a helpful video to aid in the setup of the GH4 for external recording using a Ninja recorder. He details the settings that work for both NTSC and PAL regions and shows how Panasonic have enabled 10-bit recording over HDMI – a major plus compared to just about every other DSLR or compact system camera. The extra colour information can be very useful if you are going to do a lot of work on the image in post.
Even better, if you are looking for the best HD image out of the GH4 then set it to NTSC 4K QHD and output 1080/24P 10 bit via the HDMI. I have found the quality of the 1080/24P HD recorded to the Ninja when the camera is set in 4K to be better than the GH4 set to record native HD. The internally downsampled 4K to HD via HDMI has less aliasing and the image appears sharper. This has to do with how the camera downsamples the image to get to HD vs. how it derives its 4K image and then downsamples it to HD for output via HDMI. (It should be noted that the GH4 4K image is more cropped than it’s native HD image)
There is a catch though – the camera can’t record internally to SD card at the same time as sending the 10-bit signal to the Ninja. More useful would be the ability to record 4K internally to SD card and also 10-bit HD externally – but this is impossible. The best that can be done in NTSC is to record 24P 4K (QHD 3840 x 2160) internally and 8-bit HD externally using the Ninja simultaneously. This isn’t a bad option if you need a fast way to create HD files, whilst at the same time recording a future proof 4K version to work on later. The only way to get a better HD image is to edit in 4K and then output HD, but this needs more computing power and many news organisations are not set up to handle this.
Things get even worse for PAL users though. It turns out that in order to output 1080 HD PAL signals via HDMI to the Ninja you need to set the GH4 into AVCHD mode. That means it must be in HD – no simultaneous 4K and HD recordings, and no increased quality 10-bit HD recordings from 4K mode either. This is a real shame and seems to be a problem with the way Panasonic have implemented PAL shooting in the GH4, not some fault on the part of Atomos. However I haven’t tested the GH4 with other recorders so can’t confirm this 100%.
Worse still, if you do decide to plump for recording 25P PAL HD to the Ninja it turns out that the signal is interlaced. Even though the image from the sensor is progressive, it is output as interlaced. This is not uncommon in video cameras and is usually fixed easily by applying the correct pulldown setting on the Ninja. Sadly the camera’s processing does something weird and it seems the Ninja cannot remove the pulldown easily – resulting in interlacing artefacts that need to removed in post. Far from ideal.
Hopefully Panasonic will act to fix this issue for PAL users (along with the buzz on the mic input when using non-panasonic microphones) with future firmware, but for now the only solution for external recording seems to be to record the interlaced signal and fix it in post. Watch this space.