Geoff Ross emailed me the following problem when shooting PAL video. If you have a suggestion or solution, please share it in the comments.
Also, if you are experiencing this problem, add your voice so camera manufacturers will find a way to fix this issue.
Thanks!
Larry
Geoff writes:
I have been plagued by a VERY annoying issue that began many years ago. I discovered that video panning did not go smoothly. It always had jittering regardless of the speed I performed a pan. Everyone I spoke to said I must be panning too quickly, but although I fully agree that fast speed can be a major cause, there had to be some other reason as well.
One day I changed the settings on my cameras to 60Hz, which as you know is the North American standard. Immediately the panning issue was resolved. Everything was smooth, like one would expect it should be.
This jerkiness during panning, is present with every camera I have tried, regardless of make or resolution. The key information is using PAL refresh settings compared to NTSC settings. In fact you can easily test it out yourself, by changing your own camera’s settings from NTSC 60Hz to PAL 50Hz or 25Hz, then pan horizontally. I can see it happen in the camera’s viewfinder. This is something that is certainly not subtle. It is REALLY obvious. However, if you have only ever shot using NTSC settings, or never panned using PAL settings, then you probably won’t be aware of this issue. If you don’t see it in camera, then move the file to your computer and it should be very obvious then.
I have seen so many people complain about this jerkiness during panning, but no-one else seems to have tried comparisons between 50Hz and 60Hz settings. The explanation is always blamed upon panning too quickly. Yes, speedy panning will also cause it, but there is another cause, and it has to be to do with the 50Hz setting. The difference is really amazing, and it sounds like you haven’t encountered it, but that is understandable.
The best way to see the problem, is to use 60Hz refresh first, then place your camera on a tripod, and pan whilst filming a book case, or something with lots of verticals. Then repeat the process after switching to 50Hz. I’ll be surprised if the difference isn’t really obvious for you.
As for when is it visible for me, as I mentioned above, I can see it happening in camera whilst I am panning during filming, when using the 50Hz setting. Viewing after, on the computer monitor, in any suitable software just makes it more evident. Switching back to 60Hz eliminates it, each and every time. Just to be clear, I adjust all relevant and associated cameras and computer settings to suit the change in refresh rates, and you’ll need to do the same, otherwise you’ll experience a jerkiness of a different kind, as when viewing any files captured in 50hz and displayed on a computer monitor in 60Hz, or vice-versa.
I suppose by now you will have the impression I’m fixated on panning, but I’m really not. I only pan sparingly, but it would be nice to be able to so without having concerns about the quality, and to make all my work compatible for others to view without any jerkiness being evident. However, I suspect I will likely have to contend with the problem, with a work-around, as I can’t see any manufacturer addressing it any time soon.
Larry, thanks again for taking the time to communicate.
18 Responses to Jerky Pan Problems When Shooting PAL Video
Do you see this problem on 50hz content shot by others? (Major TV shows, etc.)
That’s the interesting thing. Some panned footage by professional outlets have the same issue, and some don’t. Unfortunately, I don’t have access to the people involved, to inquire about their equipment and/or settings. What is notable, is that professionals generally do very little panning.
remember that many cameras have video stabilization. on by default, which is designed to reduce viewed movement ! 😉
It’s not easy to answer this question, as there is so much missing info, such as specific cameras being used, recording codec, example footage, etc. And, some of the terminology used is “inaccurate”.
That said, here are some very general comments:
– NTSC and PAL are legacy analog formats and usually refer to standard definition frame sizes. Modern standards, such as ITU-R BT.709 and ITU-R BT.2020/2100 are the current standards. Frame rates used in PAL and NTSC are still applicable.
– Recording footage using interlacing can contribute to, or exacerbate, the image distortion when panning.
– Panning too fast can also cause distortion.
– In the early 2000s, most consumer and mid-tier cameras switched from using CCD sensors to CMOS sensors. CMOS sensors are known to have a “rolling shutter” effect, which manifests in most panning camera movements. Higher-end cameras have a “global shutter” and don’t suffer from image distortion like CMOS sensors when panning.
– The described image distortion may be more obvious when using slower frame rates and shutter speeds. You usually want to use a shutter speed (not refresh rate) of (the inverse of) at least double the frame rate (i.e., 1/50 sec. shutter speed for 25 fps footage). Going to 1/100 sec. for shutter speed may help for 25 fps recording, though going too high can lead to strobing, etc.
– Recording at higher frame rates and shutter speeds, such as going from 25 to 30 fps, may help. In some situations, even higher frame rates might be beneficial.
– Some NLEs may have built-in tools that can compensate for the rolling shutter effect, or 3rd party plugins may exist.
There are some other considerations but I’ll leave things, as is…
Cheers.
My cameras have shutter angle facility, so the 2:1 ratio for shutter speed versus frame rate, is automatically taken care of.
The key point is the jerkiness in panning in the 50Hz setting, is evident in camera, even without recording.
One point you raised, regarding global shutter, might very well explain why some professional footage is smooth, whilst other professional output, which might not be using global shutter, has the jerkiness. Unfortunately, I don’t have access to a camera that has a global shutter. It would be an interesting test.
The fact remains, every camera I have tested for panning, can achieve smooth panning using 60Hz (59.94Hz), whereas doing exactly the same testing in 50Hz mode, the panning is jerky. If you have a solution, please let me know.
In my sentence in the above post, where I stated “don’t suffer from image distortion like CMOS sensors…” it should be “don’t suffer from the same image kind of image distortion…” to yield:
Higher-end cameras have a “global shutter” and don’t suffer from the same kind of image distortion when panning.
Whether the cameras I have used have stabilization on or off, really makes no difference. What is obvious, is the obvious difference in smooth panning between 50Hz and 60Hz settings. It is something that anyone with a camera can prove for themselves. As I mentioned, you can see the difference in smoothness in camera, even without actually recording, by just viewing when panning, using the two different refresh rates. This difference is really indisputable.
Surely the camera manufacturers can do something about it?
The slower the frame rate, the greater the chance of judder, which is the jerkiness or skipping you see when either camera movement or subject movement is too fast. It’s a form of strobing. Film is shot at 24fps (and a lot of video today at 23.98) and cinematographers learn not to pan too quickly. 50Hz is 25 fps interlaced. 60Hz is 30 fps interlaced. The slower frame rate will always show more judder. There is nothing for manufacturers to “fix” in this situation.
Steve:
Based on my knowledge, a few corrections: You can shoot 25 fps progressive, even with a 50 Hz refresh rate. Same with 30 fps, with a 60 Hz refresh rate.
This does not diminish your comments on slowing pans to reduce judder.
Larry
yes – but you’re talking about the refresh rate of the monitor, right? Traditional PAL and NTSC are both interlace, nominally 25 and 30 fps with two fields per frame, doubling the scan rate. Shooting 60Hz NTSC has less judder than 30p. And to Lorenzo’s point, PAL displayed on a 60Hz computer monitor requires an uneven cadence (pulldown) which can add unsmoothness. Alister Chapman who lives in a formerly PAL country (England) suggests you might want to avoid 25 for that reason.
In theory, Rec 2100 is supposed to handle all these frame rates natively, so whenever monitors are compliant at least that part will be simpler.
Steve:
You are correct. All NTSC and PAL video is interlaced. I think the original question was based, not on shooting PAL (meaning standard definition interlaced) but 25 FPS progressive, for, say, 1080p programs. I was thinking HD in my response, not SD.
Larry
Many mac/pc monitors don’thave a 50 hz refresh option (or you may not have set it): so jerkyness may be in the display and not in the footage.
Lorenzo:
THAT is a very intriguing concept.
Larry
Please understand, this is an issue that shows in camera, well before and display on any monitor. There is a distinct difference in panning smoothness between 60Hz mode and 50Hz mode. You don’t even need to record it to see it, you can just hold the camera up to your eye whilst panning the camera.
Yes, panning speed is crucial, as everyone acknowledges, but when everything is done correctly in terms of speed, and shutter speed etc., the underlying difference between 50Hz and 60Hz effects on panning remains. Please, please everyone, just try it for yourselves. This is beyond doubt.
Geoff:
Thanks for your patience in explaining this. Many of us don’t have 25 fps cameras we can test with this. I appreciate your stressing that you can see this directly on the camera. I lost sight of that.
What have the camera support folks told you?
Thanks,
Larry
Larry,
Nearly everyone I have spoken to about this issue, all bring up the usual frame rate to shutter speed, panning speed, and monitor refresh rate settings. They are all very relevant and correct, but they DO NOT explain this issue. I can shoot in 50p and even 100p when in 50Hz mode, but the problem is still there, albeit reduced slightly according to the frame rate. For photographers living in countries with 60Hz as standard, I can understand why you might not appreciate the difference, but I assure you, it is a real issue in terms of smooth panning when shooting in PAL mode.
Geoff:
I totally appreciate that this is an issue. What I don’t know is why it exists or how to fix it. I am also surprised that, since this is easily visible on the camera monitor itself, camera manufacturers don’t have a solution!
Larry
Larry,
I totally agree. Why does it exist in 50Hz mode, when it isn’t an issue in 60Hz? Also, why do camera manufacturers not address the problem? I would love to have access to a camera manufacturer technician to ask him/her a few questions regarding this issue.
Geoff