25P trouble, is it just me?

Y

Yoak

Well-known member
We have shot some footage over the last few weeks that all look good on a computer monitor, but when we saw it on a reference monitor in the editing suite it suffers from "strobing/lagging".
It´s very noticable in pans and it looks like the shutter is too high or/and that the footage has no motion blur between the frames. It´s very jerky.

The shutter was off, F1 and F6 was used in filmcam 25P.

I do know about the limitations on pans and movments when shooting 25p (I went to a filmschool shooting film only).
I´ve shot 25P on different Sony cameras and never experienced anything like this. The other camera man has shot a lot with the HVX200 using 25P ( I have used the HVX in 25P too) and never experienced problems like these.

I wish it was some settings we had wrong, but we tried different things with no luck.
The only way we can continue using the 101 on this shoot is to change to interlaced 2 weeks into the shoot. Not ideal, but we can´t make 25P work, and I find it very strange.

Looking at some test on my 42" Plasma today, the 25P looks very jerky, but I don´t notice this looking at the footage on my laptop.

Looks a bit like the opening scene of Saving Private Ryan, 90 degree shutter, but unintentionly
 
Just bumping this thread, but I take no one have had these problems with progressive shooting?
As we have just started the project we have decided to go interlaced from here on.
But if this is what progressive looks like broadcast with this camera it's very disappointing indeed
 
I think you can expect some "strobing" when shooting 24p or in your case 25p. Barry's book has as good treatment of this subject. It's a function of shooting 24p and is evident in any progressive format including 35mm film. If you pan too fast, or neglect to anchor on a moving subject such as your character, it becomes apparent. It depends on the focal length of your lens, how fast you can pan. Barry sites examples the American Cinematographer's Manual: "If you use a lens with a focal length of 35mm, and you want to pan 90 degrees with no juddering or stutter, and you're shooting 24p (25p for you) you have to take 18 seconds to execute the pan"

It is a pretty long time if you try it. So if you're shooting 25p whether digital or film, you will have this effect. I hope that helps.
 
hscully, the OP did state he was fairly experienced with film and other cameras shooting 25p, along with his colleague, and had not experienced this before.

Yoak, I don't have any definitive answers for you, but I don't think it is "just you".

see these threads
http://www.dvxuser.com/V6/showthread.php?238119-Strobing-aliasing
http://www.dvxuser.com/V6/showthread.php?237586-2-Problems-with-AF101
http://forums.dvdoctor.net/showthread.php?t=52733

As an aside, there are a few examples of strange "judder" throughout otherwise smooth motion on this clip, particularly at 3.08. Although I'm not sure whether it was intentional or not, or a function of the post process. Is this what you're seeing?
http://www.dvxuser.com/V6/showthread.php?239563-Movements-of-wings&p=2256787&viewfull=1#post2256787
 
Thanks for posting. I will look at these links.
Yes I am familiar with the "laws" of panning and it´s not just that. (I do have the ACM at home). Even when following a person, the person seems to skip. It´s hard to explain in words, but it really looks like there is no motion blur between the frames.
I never seen this (to this extent) on any other 25p camera I have shot with
 
it is interesting that only 25p people seem to chime up about this. I shoot 24p on my AF100 and am happy with it.

You know, the best thing to do would be to shoot another camera AND this camera connected together on a pan at the same settings and compare the images. Only then can you really determine what is different to you. You should be able to look at the motion blur and see what looks different about it.
 
This is interesting:
http://broadcastengineering.com/hdtv/solutions-judder-problem/index1.html

"Negative detail correction, as offered by Sony HDCAM and CineAlta camcorders, reduces the perception of judder.

Until low-cost HD camcorders incorporate the ability to dial-in negative detail and yet not reduce the amount of fine detail, a camera operator can try to eliminate excessive judder by setting sharpness midway between minimum and normal."
 
Hi Rick. I'm happy that you have no problems. Can I ask where you have monitored your footage?
I never saw the problem on my computer screen. It was shown to me at the editing suite on a reference monitor. Then I watched the footage on a plasma tv and I could clearly see it.
It is so bad that we can't use 25p for broadcast, we have used both Sony ex and hvx200 in 25p before without problems. If I was the only cameraman on this production experienc this I would have thought it was me or my camera, but I'm not.
I hope I can find sone settings that will eliminate this, but no luck so far
 
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Yoak, we may have seen a similar issue during our testing.
We're getting a camera in for more detailed testing shortly so we will definitely be looking out for this issue.
I'm quite worried if you're saying the 25p isn't usable for broadcast.

Have you tried recording to an external recorder, rather than the internal AVCCAM recorder?

Dave
 
Hi Yoak - just a thought (prompted by another thread) - what lens/lenses are you using? It could be, over here in PAL-land, that there could be something related to the lens/camera connection.

Basically, you've used EX1 etc - if it's without an adapter, it's the stock lens... and with a lens adapter, it's still the stock lens... so results are the same in terms of info hitting the CCD's (ie the image path from lens to sensor to digital recording). A lot simpler to test and make sure that a camera delivers what's expected when it's a fixed lens.

Now, AF101 has native M4/3 (but not a fixed lens) and then PL plus so many other flavours (or flavors in non Pal land ;) - so, and I am only thinking out loud here (as this issue keeps cropping up in regards to 25P shooting on the AF series and even on the GH2 in 24P), could it be related to the lenses used?

I presume most OP's are getting the Lumix zoom (plus a range of others) - but even the HD one was designed for the M4/3 stills range of cameras... there was a big thread with a user (one of the list from JMartin) that displayed odd stuff on a car going over snow (lack of motion blur and a very staccato effect)...

So, just 'thinking out loud' that it may be the electronic side of these lumix lenses that might not work or be compatible with 25P. I see no technical reason for this :) - just a hunch and looking at footage that seems to be a problem (on 24P GH2 and in 25P AF101 stuff).

Of course, the theory can be blown away if you're not using the Lumix stock lenses (or any type of lenses with auto focus functions & OIS etc)!

Just a possible avenue of experimentation for PAL land! At this stage too, without the AF101 being passed for broadcast (ie BBC UK 100% HD acquisition etc), we won't get any definative answers (if it is passed, there'll be required shoot settings etc).
 
I do work on the same project as Yoak and can confirm his experience due to 25p, its a remarkable difference from the dvx/hvx to AF101 in 25P. I am so dissapointed, since I love the hvx200 25P look. The ghosting, jitter and sqew we see in the pans are horrible. I am have experience with div. filmcams and never seen anything like this before. My samsung galaxy cellphone jitter less than the AF;-(
Glasses tested, so far:
Lumix 14-140mm with and without o.i.s
Lumix 7-14mm
Nikkor 24-70mm 2.8 w/ mtf adapter (w/aperture ring) and voightlander adapter (without aperture ring)
Same low quality shows when panning or following moving people with handheld cam.
What are we doing wrong here? It simply cannot be this bad.

Meidell
 
Meidell - do you have any native M4/3 without electronics - anything fully manual (like the Voigtlander .25? or old legacy still lenses or even some PL lenses etc?). This is what I was thinking in the previous post - that there may be some electronic issue... that shows up in 25P? Or makes a problem visible that was hidden previously.

Basically, by going to a fully manual lens, we could rule in (or out) any electronic or 'digital route' type errors.

If any type of motion (pan/HH etc) shows off the issue, it's maybe similar to the problems some people are having with GH2's in 24P (and maybe that circles back to the lenses used?).

Try & show footage if possible - lots of users here, so maybe Barry can chime in at some point...
 
MadMonkFish said:
Meidell - do you have any native M4/3 without electronics - anything fully manual (like the Voigtlander .25? or old legacy still lenses or even some PL lenses etc?). This is what I was thinking in the previous post - that there may be some electronic issue... that shows up in 25P? Or makes a problem visible that was hidden previously.

Basically, by going to a fully manual lens, we could rule in (or out) any electronic or 'digital route' type errors.

If any type of motion (pan/HH etc) shows off the issue, it's maybe similar to the problems some people are having with GH2's in 24P (and maybe that circles back to the lenses used?).
Try & show footage if possible - lots of users here, so maybe Barry can chime in at some point...
Click to expand...
Thx man. I will test my vintage simple nikkor 50mm 1.4 (fully manual) right away.....I'll try to post some footage later too.
Meidell
 
I've looked at my 24P footage on an LCD consumer panel. The only reason I mention 24p as opposed to 25p is that I've read other threads mentioning 25p and issues like this, but not many if any 24p threads (cannot recall any specifically). I say this because I wonder if there is something strange going on.

If you have the chance, this is what I would do just to help identify the problems.

1) Shoot in 25p a shot with a slow pan. Follow the golden pan rule, it should take any object in the scene 7 seconds to go from one side of the screen to the other to avoid strobbing at 180d shutter. 25p is faster, and this rule is for 24p, but it puts you within cinema standard for 24p capture.

2) Shoot the same test at 24p. Remember you have to use a different card to record on. You cannot mix footage from both camera modes. Again, 7 seconds.

3) For test (1) above, if you can, mount an HVX or another camera you are happy with the motion blur above the AF100 and record the same scene with the same pan speed (again, following 7 seconds) and also with 180d (or 1/50) so the actual motion blur can be compared.

What doesn't make sense to me is that typically, things look MORE stroby on my computer monitors in footage that I have shot to be stroby (1/250 shutter speeds for me) than on actual consumer equipment. That is why this is so strange.

Second, the read/reset time of the AF100 is around 12ms. This is VERY fast compared to other rolling shutter LCDs. It is about the same speed as a full raster from the Red One. It is almost twice as fast at the 7D. There will be skew, no question, depending on your pan speeds. This is expected, and frankly, not that bad to me. What I like about 12ms is that it isn't jellowy like 20ms gives you (and higher).

I also use all manual lenses at the moment.
 
FYI I´ve shot mostly with the Oly Zuiko 14-25mm, Lumix 7-14mm (not so much though), Lumix 20mm f1,7 and older Canon FD glass, 50 & 100mm.
The Canon glass has been used for landscape and stock shots, so not much panning in those. I will try them out just to make sure, but I doubt it will be any better.
I would love to find a solution to this, but so far it´s interlaced, and that´s not the solution we are looking for.

PS I´m out on location so I don´t have time to test with multiple cameras yet
 
Yoak, Im trying to think of where this might be coming from. FWIW at this stage Ive shot a bunch of stuff in 25P and in my edit suite Im viewing on a Pana pro plasma Im not seeing anything of concern - as in watching my footage Im not seeing stutter in my shots.

Also it could be purely down to how I shoot - I dont tend to pan shots unless I follow action so it is possible Im not noticing it. The only lens I have that is the same as you is the 14-140. SO youre seeing it at all focal lengths on this lens? I will do some panning in the next few days and check it for you.
 
Thanks Noel.
What settings are you using if I may ask?
We even notice the problem following a person walking through a building, it´s just very jerky/studdery
 
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