GH4 Help with GH4 Slow motion 60 fps

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benne13

Member
Hello,

I've had my GH4 for several months now and love it. But when I try shooting in slow motion specifically 60fps the video is recorded extremely slow but on the viewfinder the motion is what I expect from 60fps.. Smooth fluid but during playback it's 1/3 the speed its supposed to be and unusable footage. any suggestions? I'm using 125 shutter speed with 60fps and the rec frame rate is 24fps. I must be doing something wrong within my settings.
 
Let me get this right. Do you want to shoot in slow motion, or in 60 fps? If you just want 60fps, that plays back at 60fps, you change your frequency setting to 59.94, which necessitates turning the camera on and off. If you want slow motion, you switch to 1080p VFR mode, and dial it to 60fps, or what ever speed you want. Only issue is autofocus is not usable in VFR mode. This is why a lot of people prefer shooting at 60fps in 59.94 frequency mode, where autofocus works, and changing the frame rate after the fact in post to get slow motion.
 
benne13 said:
Thanks for the response. I asked the guy who shoot this video and he mentioned doing it on his GH4 at 60fps in 1080p but when I change my settings to 60fps in VFR mode my picture quality isn't as smooth and it 4 times slower than his..

https://www.youtube.com/watch?v=POzp_g-9s-A
Click to expand...

This is a 60p video, so he's probably changing the speed in his NLE to something else in the slow part. On the GH4 when you pick VFR, it takes 60fps and plays it back at whatever the system frequency is set at. If it's set at 24, then the 60 plays at 24 which is 2 and a half times slower. 29.97 it's 2 times slower.
 
Thanks. So if I change the system frequency setting to 29.95 at 60fps I could get the same results? BTW I have the international GH4 version so I don't have 29.95 in system frequency but rather 59.95. Is it basically the same thing?
 
benne13 said:
Thanks. So if I change the system frequency setting to 29.95 at 60fps I could get the same results? BTW I have the international GH4 version so I don't have 29.95 in system frequency but rather 59.95. Is it basically the same thing?
Click to expand...

Yeah, sorry, there is only a 59.94 setting on the US one too. VFR mode is available in the REC Quality menu at 1080p 29.97 when you switch to 59.94 system frequency. You could also just shoot 1080 60p and then adjust in post, which is what the youtube video did.
 
Maybe to clarify a little more:

If you use VFR in 24p mode and set VFR to 60fps,
-You won't get any sound recorded with your clip.
-You'll be recording 60fps, but the camera will be putting it into a 24p file, so it will be automatically going 40% speed when you watch the clip in the camera or on your computer.
-You can always speed it back up to 250% in your Editor and get the original look, but no sound still.
-You can also go all the way up to 96fps in a 24p file, which will give you even slower motion, but the image does get a little softer (not a bad image. Looks like a 5DMII... zing!)

If you set the camera frequency to 59.97 and just shoot at 60p:
-Your file is shot at 60p and plays back at 60p in camera and on the computer, so looks normal.
-Your video also has audio.
-You have to slow it down when editing the video later.
-Without turning on VFR again, you cannot shoot 96fps. Only up to 60p.

Hope that helps clarify things.
 
For me the easiest thing is to always shoot 60fps (50 in other parts of the world). Place the footage into a 29.97 project and in my NLE software change the clip properties to 29.97 for 50% slow motion.
 
I have a US GH4 and it has 25 and 50p option. You have to switch the system frequency to 50hz to see the 25 and 50p options. It is available on all GH4's regardless of where you purchase the cam, if I'm not mistaken.

I would strongly suggest you shoot in 1080-50p 200mbps mode and slow down your video in post if you want to the highest quality. If you shoot in VFR mode at 50 fps, where it automatically plays back in 25p mode, you loose quite a bit of quality, audio and any sort of autofocus. If you want slower motion than 50%, you're stuck with the lower image sharpness and bit rate with no audio.

Get into the menu and sort out your system frequency so you can shoot in 25 and 50p, then do a bunch of testing with the different modes so you can be comfortable with which way you want to shoot your next piece.

Cheers,
Pete
 
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