GH4 Flicker occurs when panning or fast-moving images?

S

Sweden

Member
I've bought GH4 and started to test shoot a little and there's only one thing that bothers me and unfortunately it seems like all movies suffer from this problem so far (more or less and not just mine), namely flicker.


There seems to be a problem when panning or fast-moving images, as if the camera can not keep up?
Maybe it's the low biterate that does this. Hopefully the Atomos Shogun remedy this because otherwise it becomes difficult to trust the camera as it is now.

Here are some examples:

https://vimeo.com/99523009 (Philip Bloom beautiful film from Thailand) between 42-49 seconds flicker.

https://vimeo.com/groups/gh4/videos/99150436 between 11-27 seconds flicker.
 
I see the problem in my GH4 4K footage too, but when I watch frame by frame the displacement in every image is regular and clean.
For this reason I think (and hope) the cause might be a lack of motion blur or some issue with the playback of the large 4K video in a much smaller monitor.
 
Upon further inspection I must say that I actually see some duplicated frames in the Normandy footage (downloaded from Vimeo), but not in the Pilip Bloom's or in my own.
Then in that case it just might be bad post or compression.
 
Stutter has always been a part of panning, even on film. And using a fast shutter speed does not help matters since the non image making part between each frame's exposure is increased: a motorcycle passes across frame: while 1/50th exposure might provide the feeling of continuous flow, it will have more motion blur, and less "sharp", than 1/1000 sec exposure. But, with 1/1000 the motorcycle will have covered much more ground between one exposure and the next, so stuttering is more noticeable.
It boils down to knowing how to pan - max pan speed for a given focal length - and your preference of motion blur Vs higher shutter speed with slower pan…..
 
Sweden said:
I've bought GH4 and started to test shoot a little and there's only one thing that bothers me and unfortunately it seems like all movies suffer from this problem so far (more or less and not just mine), namely flicker.
Click to expand...

This is mostly about frame rate. Slow frame rates, like 24fps, will show more flicker when panning / tilting /moving the camera than will higher frame rates. This is why cinematographers always try to keep panning speeds to a minimum. Worst I've seen was from a helicopter flying down a canyon just about the river. Both sides of the image (the canyon walls) flickered like a beast. And this was with 24fps film, not video.

This is part of the argument for higher frame rates, like 48 fps, and 60 fps. These rates make motion considerably smoother, but "less cinematic". It's difficult to have it both ways.
 
It's very strange because I also have the Panasonic HPX301 and it does not show this type of behavior at all?
However, I use the 1/48 shutter speed tought in 1080p in 25p (PAL land) for my HPX301 could it be the reason i think not?


I find it hard to believe that there is something with the shutter speed, but I suspect it has to do with GH4, but why?
 
Hi Sweden.
I'm experiencing exactly the same issue's on my 5 days old GH4, even with a Steadicam!
In all modes! (4k,4CK, 1080p all in 24p or 25p) Tried different shutter speed multiple times, but it stays the same. (thought maybe 1/48th was essential for a good looking picture when shooting in C4k 24p/Hz, so i tried that also with synchro scan)
Please take a look of my sample video, shot in C4k straight from my card. (https://www.wetransfer.com/downloads/354c8b167d87a4396186753fddf6b01220140629120309/163ce5)
Even though with Steadicam and pretty discrete movements (IMHO) it looks horrible annoying.

I also saw this here on the board:
''http://panasonic.net/avc/lumix/

Improves recording video capabilities….''

http://www.dvxuser.com/V6/showthread.php?325536-Important-new-GH4-firmware-update-released-7-1-14

Gonna try that now!
 
I agree with what Stuart U said. Capturing in 720p or 1080i will eliminate it for the most part. These formats don't "double" frames. Otherwise pan much slower with a slower shutter speed.
 
I think it happens a lot on web delivered video because it is often captured in 30fps but delivered online at 24fps. So the original may look fine when edited but the lower framerate of the web version exposes the issue.
 
There is no way around it, at 24p, pan & tilt speed must be "extremely" slow to avoid strobing. As example: panning at 24p and 40mm requires approx. 14 seconds for an object to cross your field of view and avoid strobing. This has been an issue since film and charts can be found online to help you.

To test this for yourselves, try a pan at 24p, then 60p and see the difference.

Good shooting.
 
Every GH-series release (except perhaps the GH3) has produced a slew of posts along these lines. When I'm not posting from my phone I'll dig up some example links. Each time it has boiled down to a mixture of a sharp image with too-fast pans and/or online video compression artifacts and/or computer monitor refresh rate quirkiness.

The latter caught me out at first - I was fretting about my GH2 stuttering when I was viewing on a computer LCD monitor ... when I started viewing on my HDTV the image was fine.

Edit: here's an old thread that mentions the monitor issue: http://www.dvxuser.com/V6/archive/index.php/t-238636.html
 
I agree a monitor or tv will accentuate it or hide it depending on how fast it's own "shutter" is (or frame interval).
 
But why it is'nt on my 650D, shot with Steadicam and exact the same settings? (24p, NTSC, 1080p)
Can someone please explain?
 
You see it a lot on american tv (NTSC 30fps) delivered on PAL (25fps). I first noticed it on Babylon 5, every external ship scene with movement strobes bad. Looks fine on the NTSC copy on a tv/monitor that can deliver the native framerate.
 
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