View Full Version : XDCAM EX 1 motion questions
Hi Folks,
I'm prepping a documentary that we're shooting the XDCAM EX1.
The documentary focuses on a couple of VERY fast moving dancers and the shooting style involves a great deal of camera movement.
I would like to shoot in HQ 1080 24p, however my tests have the following issues.
-When the camera is moved, two issues occur: a judder and a smear. Both settle and focus in when the camera stops moving.
-The smear (I'm using the term to refer to a blurring that happens along with the judder) seems to retreat a bit at a faster shutter speed. However the judder is still there (and some remaining smear) and with the low light environments we'll likely be in, a faster shutter speed is not always an option.
HQ 1080 30p will still have both issues, though to a much lesser extent. There's a visible smear when the shutter is open. The smear retreats when the shutter is closed, but a judder becomes prominant.
Over all I think 30p is less attractive aesthetically. But the issues 30p has capturing movement are less distracting then 24p. I really do like 24p's look when it's still and would love to find away to make it work for all scenarios.
Lastly, I have shot 24p before on the HVX200. We were shooting the same subjects and in 24pn mode. We didn't have these issues, so I don't think it's simply "the nature of 24p".
Does any one have experience with the XDCAM EX1? Do you have any advice on how to get 24p to smooth out in movement?
Thanks so much,
-Hoku
Hoku Uchiyama
writer - director
510.384.4059
www.hokuuchiyama.com
hoku@hokuuchiyama.com
PerroneFord
01-08-2009, 03:24 PM
What shutter speeds are you using to capture this? Shutter OFF is going to look terrible no matter what camera you use.
No the shutter isn't off. I did test that though.
In 24p I've been testing in 1/32 and 1/48 and up to 1/120. Anything higher is unrealistic for our low light situations.
In 30p I've tested in 1/40, 1/60 and up to 1/120.
Both have more or less blur and judder depending on the shutter speed, but 30p is less distracting... but so much more video in look. Again, the HVX200 worked with 24pn, so I know it's not just the "nature or 24p". I suspect it has something to do with the different ways the HVX and the XDCAM EX compress information.
I would LOVE a work around to smooth out 24p if anyone has one.
Thanks so much.
Best,
-Hoku
PerroneFord
01-08-2009, 03:48 PM
Could be the recording codec, could be CMOS, could be a combo of both. But shooting high motion in low light, with a slow fps and slow shutter isn't going to be the answer.
Do you have any examples of the captures from the HVX and the EX1?
Hi there,
Sorry, I don't think I'll be able to post examples at the computer I'm working on.
While high motion is absolutely a huge concern with this doc, the issues I'm seeing can be seen when making subtle pans, outside in the day. If you raise the shutter speed, you're still going to get judder (with the blur minimized a bit). When you stop the pan, the judder is gone and the focus is back.
Thank you for your thoughts. Any more from you or others is greatly appreciated and welcome.
-Hoku
Candiness
01-08-2009, 09:48 PM
You raise my chief concern with this camera. I, too, am looking to do a film sequence with dancers, and from what I have seen, the EX1 is beautiful when the amount of panning is modest and movement is fairly subdued. Others may have a different experience, but this has been mine.
Rick Lutec
01-08-2009, 11:38 PM
I too have some concerns regarding these issues. I have an EX1 that I picked up for a pretty good price and plan to tape contemporary dance pieces with it but, many examples of footage I've seen show judder during pans. The clip examples often posted all look great when the shot or cam is static but some clips that involve movement do show judder. I know certain frames require slow or minimum pans but what about recording in 60i? Would the problem still be evident? A Sony product manager did suggest 60i for best fluid movement but I still don't know why the cam has such judder issues. What works best to avoid the problem besides a different cam?
Thanks
There is no judder filming in 1080 50/60i or 720 50/60p. Film in 24/25 and even 30p and like any other camera, you can introduce judder. This is not specific to the camera but your filming technique.
As I am not experienced in shooting for 25p, I rarely use it. Only shot a music video in 25p where I knew the camera wouldn't be panning much etc You got to know your own limitations as well as your equipments.
In the minimal tests I've done with 60i, I haven't seen much of a problem. The camera tends to blur and judder a bit when panning or moving at all. But the more frames per second, the more minimal it is (from what I can tell.)
Guy, thank you for your response, but what you've stated has not been my experience. I've shot the same subjects, with the same style (lots of handheld movement) with the HVX200 in 24pn mode and have not had the same issues. I don't know if there's some trick to getting the XDCAM EX1 NOT to have these issues, but I don't feel that they come hand in hand with 24p.
All the best,
-Hoku
www.hokuuchiyamma.com
Its always a case of getting to know your equipment as well as your techniques. The same shutter speed with the same frameing with the same frame rate with the same camera motion on the same playback device in the same viewing environment will result in the same level of 'shudder', its an artefact of human visual perception, not aquisition.
That is unless like the JVC there are electronic tricks being used to try to mask it such as their frame blending, but by doing that you are really changing the initial parameters...
Iudex
01-11-2009, 09:11 AM
The judder is becuase of the fame rate or the camera?
I mean, 16mm and 35mm when filming at 24 offer the same problems?
I believe so, which is why cinematographers learn to operate with great care to avoid this judder. I don't know them but there are meant to be rules to follow with pan speeds to avoid these problems.
Iudex
01-11-2009, 04:58 PM
Oh, that is very interesting. In the first place I thought "Probably it's just the camera...", but watching closely some films I slowly changed my mind... so I begun to study how to avoid the problem... first thing I learned (very obvious and basic) is based on the nature of the problem: movement of the objects... but movement of the objects inside the screen. So if you follow someone running, but keem him always in the same place of the frame, it helps.
Another thing I guess cinematographers do is shoot at a higher framerate when they have difficult movements... could this be? Of course, they would afterwards playback at 24p blending frames or something.
On the other hand, this camera's ROLLING SHUTTER probably makes the problem worse, because even at low pan speeds it surely contributes to image deformation.
MitchLewis
01-11-2009, 06:25 PM
Yesterday I hooked our new EX3 to our new JVC 24-inch pro editing monitor. I connected directly from the camera's HD-SDI out to the HD-SDI in on the monitor. I shot the same scene at 1080 30P, 1080 60i, and 720 60P. None of them were free of the "smear" of judder, but 60i was the besst. This was all shot at a 1/60 shutter speed. I tried to figure out how to turn the shutter off for shooting 1080 60i, but I couldn't figure out how to do it.
The point is, from the very befinning, people (Berry Green) have pointed out how these cameras look fantasitic when static, but the minute you add movement they loose resolution (for lack of a better description). I'm not sure if this is an issue with the 35mbs codec or what. Maybe I should have tried recording the HD-SDI signal at ProRes 422 HQ. It would have been interesting to know if that would have made a difference. Unfortunatly I'm on a steep learning curve with this camera (and 35mm adapter) so I haven't had time to test everything as much as I would have liked.
Anyone else?
...The point is, from the very befinning, people (Berry Green) have pointed out how these cameras look fantasitic when static, but the minute you add movement they loose resolution (for lack of a better description). ...
If you pan a $50K Medium Format digital camera and take a photo with a 1/60 or 1/120 sec shutter, would you expect the image to be sharp and maintain 'the resolution' of the sensor?
Now try the same pan with a 1/2000 sec shutter, it will look better.
Every camera will loose apparent resolution of definition in the image when you pan as the frame will blur from the motion of the pan.
Once again, its got nothing to do with the camera. The image is not loosing reslution, it is capturing that motion blur in full resolution.
MitchLewis
01-11-2009, 08:29 PM
I'm no expert but I disagree Guy. If the image was "motion blurred" I would agree, but it doesn't look blurred to me. It's more of a weird resolution issue if you ask me.
Don't get me wrong, I LOVE the look of our new camera and I'm very happy with it. But if we could find a way to make it even better, I'd be interested. I'll try upping the shutter speed and see if that helps.
If upping the shutter speed helps then to me that would confirm it is simply motion blur, a fast shutter speed has the effect of sharpening the appearance of moving objects in each frame captured (which is why photographers use fast shutter speeds too).
MitchLewis
01-11-2009, 10:22 PM
This is possibly not relevant, but I've shot DV for 7 years now at 1/60th and never had this issue. But maybe it's because it's DV and not high enough reolution to notice. (I sure wish I had tried turning up the shutter speed yesterday when I was testing......give me some more time.....really busy this week at work......first actual shoots scheduled with this camera)
I hope you're right Guy.
Yes Mitch but did you try shooting DV with 24p ? I think it will render the same result as what's being talked here.
What does the shutter OFF setting actually do ? It sets the shutter at 1/24 or whatever framerate you are shooting on ?
PerroneFord
01-13-2009, 06:51 PM
I just did a little test at 30p I think you guys will find interesting. First time I've shot in 30p so hopefully you'll indulge me. The shutter was at 180 degrees.
http://vimeo.com/2821010
Download the actual video, don't try to watch it off Vimeo.
I don't see any noticable loss in resolution I could put down to anything but motion blur but I did notice a regular stutter. I have a feeling it was more related to either my LCD screen updating or my quicktime player etc, i was too regular (like every second) for what felt like 1 frame. Could it be some type of frame rate conversion has happened somewhere?
PerroneFord
01-14-2009, 06:24 PM
BINGO! Vimeo doesn't support 30p so it did a 24p decimate at their end. I forgot this. I will redo the shoot at 24p with both the ex1 and the DVX100 later in the week. However, downloading the original file should eliminate this. If you're seeing it after downloading, it's not the video.
But it was interesting to see that there was no appreciable loss of resolution whatsoever. The fine text was clear the entire time other than like you said, motion blur. Also looking at the vertical edges and lines, there was no appreciable skewing either.
I don't know how fast people are panning, but when shot with "Hollywood" speed, everything look A.OK. as far as I can tell.
MitchLewis
01-14-2009, 09:51 PM
I've been shooting non-stop for the last three days, when I get a chance to catch a breath I'll post some footage as well. Perrono's pans look better than mine.....I think. I'll know more tomorrow.
Iudex
01-15-2009, 12:30 PM
Perrone I've downloaded it and seen the stutter that Guy was seeing (it sounds like it's the same one).
Hey... can you set shutter at 1/24??? Someone said that a few posts behind.
Does anyone now which shutter speed/angle is the usual one when shooting 35mm at 24 frames? I was also wondering... shouldn't the EX1 enable you to change the speed and the angle at the same time? As far as I know these are two different things in photography, but the EX1 seems to fix speed when adjusting by angle and fix angle when adjusting by speed, am I wrong?
Cheers..
The "industry standard" settings when using adapters and 24p is 1/48 or 180 degree shutter angle.
I was asking not saying about setting the shutter speed at 1/24 a couple of posts ago. I think if you set the shutter to OFF should accomplish this but i'm not sure.
Shutter speed and shutter angle mean the same thing. Refering to the shutter speed in degrees is practiced in the motion picture industry because film cameras don't have a curtain type shutter mechanism like the ones found in still photography cameras. It's a disc with a part of it cutout. When the cutout part of the shutter passes in front of the film it exposes it to light. The timeframe in which this happens is the shutter speed and it's controlled by how large or small the angle of the cutout is.
So a 180 degree angle is equivalent to a 1/48 shutter speed.
Here's a formula to convert shutter angles to shutter speeds http://provideocoalition.com/index.php/freshdv/story/shutter_speed_vs_shutter_angle/
Hope this explains it.
PerroneFord
01-15-2009, 02:17 PM
So here's a question.. and I'll verify this tonight.
Lets say I set my frame rate to 24p and my shutter to a speed of 1/48. If I then change my frame rate to 60i or 30p does my shutter follow suit and maintain a 180 degree shutter or does it stay where it was set?
If we make the shutter speed adjusted by ANGLE instead of an explicit speed, does it have the expected behavior in the previous example and change from 1/48 to 1/60?
I'll get on that this evening, and shoot a couple more tests.
Why should your shutter speed or angle change when you change from 24p to 60i ? I don't understand.
The EX1 has an electronic shutter and it has nothing to do with the disc type shutter in film cameras. The reason it lets you set the shutter speed in degrees is to make it easy for film folks or people that are used to the shutter in angles to work with it.
PerroneFord
01-15-2009, 05:32 PM
Why should your shutter speed or angle change when you change from 24p to 60i ? I don't understand.
The EX1 has an electronic shutter and it has nothing to do with the disc type shutter in film cameras. The reason it lets you set the shutter speed in degrees is to make it easy for film folks or people that are used to the shutter in angles to work with it.
It should because I'd LOVE it to keep that relationship. Even if it went to the default 180 degrees when changing modes, that would be awesome. But we'll see what happens.
NOt sure between interlaced and progressive but from what I have read, it you set it at 180deg and change from 24p to 60p the shutter speed will change from 1/48 to 1/120 automatically (well it has to, to maintain the 180 setting).
PerroneFord
01-15-2009, 10:44 PM
Well some answers,
I verified that if you leave the shutter angle alone, and change frame rates, the angle changes along with you. VERY convenient if you are trying to work by F-Stop (or T-Stop).
Also, some new videos are up on Vimeo.
The 24p pan test with the EX1. Download it to see the HD verison as I only get one HD video per week...
http://www.vimeo.com/2846111
And the 24p comparison test with my DVX100
http://www.vimeo.com/2846143
You be the judge...
Iudex
01-16-2009, 05:10 AM
It now looks ok Perrone!
I still have many doubts about the EX1's 24p mode being 'just like' working with filmic. I think filmic is much more permissive, maybe it is more like EX1's 30p mode regarding stutter. For example now I think about Rodriguez' El Mariachi, which was shot in 16mm very gorilla style and I don't remember seeing any stutter anywere. Maybe there is some frame blending we should be doing to soften this stutter?
Mind if I ask a side question? Why Vimeo/Exposure Room and not YouTube's HD option? I've tested it with the EX1 and it looks just very good. Thanks!
PerroneFord
01-16-2009, 05:39 AM
I've done HD on Youtube and it's fine, but users can't download the original file there which I thought was important for this little project.
Guy please understand if shutter angle and shutter speed are the same thing just expressed in different ways. If you change from 24p to 60p nothing changes it's still 180 degrees or 1/50 but (actually it maybe changing to 1/60 i'm not sure) the frame darkens a bit because there is less light hitting the sensor at 60 fps.
In film cameras the same happens. You have to compensate by opening up the iris when doing slowmotion work and closing it down when doing less than 24 fps.
Iudex, film is film and digital is digital. The stutter you mention may be bcause of bad compression or some other technical issues but the effect is almost the same though it looks different on digital and on film because they are different mediums.
PerroneFord
01-16-2009, 10:33 AM
A bit more on the shutter angle/shutter speed issue.
Let's say I am on a shoot and I am going to shoot part of the shoot in 720/60p and the rest in say 1080/24p. I'd like a shutter angle of 180 degrees for both. Essentially, I want a common shutter of half the frame rate.
If I shut a shutter speed of 1/120 for the 720/60p shoot, then go into the menu and change the camera 10 1080/24p, the shutter stays at 1/120 which is NOT what I want. I want that shutter to change to 1/48. So I have to do it manually.
If I choose to do things by shutter angle, then the half-framerate shutter speed is preserved no matter what framerate I select on the camera.
Make sense?
Yep I understand what you are saying but I don't think it works this way. Maybe someone with omre experience will tell us.
PerroneFord
01-16-2009, 12:43 PM
Yep I understand what you are saying but I don't think it works this way. Maybe someone with omre experience will tell us.
It works JUST like that. I tested it last night.
...
If I choose to do things by shutter angle, then the half-framerate shutter speed is preserved no matter what framerate I select on the camera.
Make sense?
Totally, this is exactly what I was saying as well, although I would have said the shutter speed is double frame rate, not half. I thought when shooting at 24p with a 180 shutter angle you get 1/48 sec shutter (wouldn't half be 1/12sec?), if you turn the shutter off (switch at the font of the camera) you get 1/24sec
Barry_Green
01-16-2009, 05:18 PM
Well, half means half the exposure time. 24fps means one frame every 24th of a second, and so a "half" shutter would expose for half that 24hz time, or 1/48th.
The name of the number is double, but because it's a fractional denominator the doubled size means the actual duration is half.
cool
tomatoe, tomatoe. Oh, that doesn't work so well when you don't actually say it ;-)
emotepix
01-17-2009, 08:52 AM
ummm.... toe-may-toe, toe-mah-toe? :-)