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Sony NXCAM NEX-FS100 CineAlta
An interchangeable lens AVCHD camcorder using E-Mount lenses.


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Old June 20th, 2011, 05:04 AM   #1
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25P juddering motion.

I have had my FS100 PAL version for some days now. When I use it in 25P most of the motions in the frame sometimes judder. It is not consistent, the same all the time. It is worst in high contrast areas. My setting is 25P shutter 50 or 180 degrees. I have tried various shutter settings and it only makes it worse!
The strange thing is. It is not always the same. Just if the processing in the camera sometimes canīt cope, or if it makes a mistake.
I have hooked the camera up to my 46 inch Panasonic plasma to see if it is the codec. It is not.
It is the same if I record something and play it back from the camera or if I monitor it live out of HDMI!
I have made a test comparing my old and trusty F330 and the FS100. The F330 behaves as predicted. I can see the 25P motion as a blurring shift from frame to frame, when panning past an open door. The FS100 is more like an old cartoon where there is some missing action between the frames.
In 50i and 50P there is no problem.
If you look at Alisters test film the part with the birds and the boat going past behind the trees, it is doing what I am talking about! In the sequence with boat passing, there is a side by side picture with the F3 and the FS100. The F3 is smooth and the FS100 is juddering!! When I first saw it, I thought it were because of the camera being a NTSC pre. production model.
As it is for now I can not use the camera in 25P before there is a solution, or I can predict when the juddering will stick itīs ugly head out.
Besides that I love the picture the camera produces. I donīt like the form factor and the screen on top, but I donīt see the poor built quality others are talking about. In my opinion the camera is the best you can get for this kind of money. I put picture quality above all. The form factor can bee treated with, but the picture is as it is!
So if the juddering in 25P can bee sorted out I am a wary happy guy.
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Old June 20th, 2011, 08:10 PM   #2
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Re: 25P juddering motion.

Oh Oh...
This guy has the same issues.
Fs100 25p shutter speed test - Sony NEX-FS100 Super 35mm User Group on Vimeo

Oh boy, there seems to be a major issue here!

You should contact Sony and send it in for repair. Otherwise they may not become aware of the problem.
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Old June 21st, 2011, 06:54 AM   #3
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Re: 25P juddering motion.

Not likely an "issue" in terms of the camera. My book on the VG10 and my new eBook published by Broadcast Engineering explain exactly why one WILL SEE "excessive" judder with the VG10 and FS100, but not with the F3. Nor see judder with the other expensive Cine Alta cameras.

ANYTHING that increases the hardness of moving edges is going to result in very visible motion judder. In fact, Larry Thorpe mentioned repeatedly when we talked about this issue, that monitor brightness must be controlled lest judder to look even worse. So shutter-speed (to add just enough motion blur),scene brightness and contrast, the sharpness setting, the lack of a high lens MTF. (A major factor!)

Judder will come and go depending on the magnitude of the motion vectors of the moving objects in the scene. It will sometimes be foreground judder and sometimes background judder.

The F3 I believe has the Negative Detail control Sony developed to reduce judder on Cine Alta cameras. It's part of what you pay for in the electronics of the F3.

You can use Cinema techniques to try to control motion judder.

One other possibility: your monitor is not detecting 1080i50/25PsF. (It's very likely that what's sent via HDMI.) Turns-out Panasonic plasma's often had poor deinterlacing circuits. Especially the older ones or the cheaper small monitors.

PS: what lens it being used? The kit lens by chance?
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Last edited by Steve Mullen; June 21st, 2011 at 07:30 AM.
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Old June 21st, 2011, 07:55 AM   #4
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Re: 25P juddering motion.

Thatīs not psf footage. The camera records usual 25p. Are you refering to the VG10?

So dialing down detail on the FS100 would help?
Is this maybe related to the AVCHD codec so it would improve when recording to en external device?
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Old June 21st, 2011, 09:09 AM   #5
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Re: 25P juddering motion.

Thanks for your replies.

Steve the lens used on the FS100 is the new Zeiss ZF2 35mm f1.4 set at f4

I am aware of the Panasonic problem with interlaced, but the problem is often so severe that I am able to see it on the FS100 monitor!
To put it in a other way. It looked the same on the Panasonic as it did on the FS100.
My test were performed with both cameras hooked op to the screen at the same time.
The F330 trough component and the FS100 trough HDMI. Both cameras were placed so that they had the same FOV.
The exposure were set equal and I just switched between the two to see the difference.
I must admit that I stressed the 25P to the limit to reveal the difference! I am aware of technique of shooting progressive footage.

If you are right on the subject, you are confirming me in my own conclusion, that the internal processing in the camera is not up to the task. If it is so the whole idea whit this camera falls to the ground!
I donīt hope this is the case and there is another explanation to the problem, or it is something Sony will fix trough a firmware update.
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Old June 21st, 2011, 01:43 PM   #6
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Re: 25P juddering motion.

I have been reading Steves article about motion judder.
It explains why the judder occurs... Read it!!

I have been investigating into the detail settings in the FS100. There is some ability to adjust the balance of detail.
Before it has any effect the manual setting has to be turned ON in the detail setting menu.

After some trial and error I have found out changing the settings has an impact on motion judder in high contrast areas..

I have to investigate more to fully understand the different settings and thereby achieve the optimum result.
The goal seems to be to reduce edge sharpness and to preserve fine detail.
This is a balance and I wish Sony, in the manual, had been more informative in this area. Why do we have to invent the wheel if is already done????

BAD BAD BAD Sony... You know this camera is for film-making and thereby is is going to be used in progressive mode..
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Old June 22nd, 2011, 01:24 AM   #7
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Re: 25P juddering motion.

Reducing detail is a good option on cameras without a negative detail control. If you can, shoot in low contrast lighting. Allows follow a moving object. And use a shallow DOF to keep background objects with motion from being recorded with sharp edges. Never let objects speed through your frame or Pam rapidly.

The better the lens the less judder.

PS: When 25p is sent via HDMI it is likely sent as 1080i50/25PsF. Don't know about component.
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Old June 23rd, 2011, 11:30 AM   #8
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Re: 25P juddering motion.

Thanks Steve for your advice.

There are some settings in the detail menu I have to explorer further.

With a little care in the detail settings and shooting stile I think it is possible to obtain a decent result, and therby render the camera usable for the kind of work I have purchashed it for.

On the other hand. If my filmwork develops as expected the FS100 is going out and an F3 is comming in.
I am not saying the FS100 is a bad camera. In fact I think it is a extraordinary super camera for the money.
On the long run, it is just not my kind of camera with the awkward formfacktor combined with the other shortcomings it has.
A former DSLR shooter will be at home, but me come from a full size shoulder camerae, it is something of an upheaval .
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Old June 30th, 2011, 04:21 AM   #9
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Re: 25P juddering motion.

I've just bought the FS100 before reading all the above...

And all footage shot in anything else than 50P 1080 looks terrible! Extreme juddering!

Thats why I'll only shoot in 50P 1080, but the problem is that Final Cut Pro 7 does not support it and I haven't been able to find a Sony driver that does. Do some of you have a solution?

I've contacted Peter Sykes from Sony UK, and he will put me in contact with a Japanese engineer tomorrow, but if anyone has an answer today, it would be just great.
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Old June 30th, 2011, 05:12 AM   #10
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Re: 25P juddering motion.

This issue is concerning me a bit as I am in Pal land.

I'm waiting until they are available here in Oz to buy one (July apparently) but if footage is going have the juddering stuff like what I've seen on the Vimeo clip and there isnt a solution via detail settings then it would be pointless buying one at this point.

Ive sold my 7D in anticipation as well!!

Cheers

Jamie
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Old July 4th, 2011, 05:10 AM   #11
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Re: 25P juddering motion.

As Steve has already said, one of the of the key issues here and I believe a very strong clue to what is going on is that most complain that the issue is most pronounced in areas of high contrast.

Our visual system uses contrast to detect motion, in areas of high contrast any non-smoothness of the images motion will be more noticeable. The higher the resolution/contrast or more precisely the higher the MTF of the camera system the more we will notice judder and stutter. Just take fast motion in an Imax film as an example, it stutters like crazy, in part because it's very high resolution/contrast from a 70mm tall frame.

The FS100 and similar high contrast/resolution cameras will appear to stutter at low frame rates more than a low contrast/low resolution camera. Add to that the FS100's near complete lack of noise, which through it's random nature will help mask judder and stutter and you have a worst case scenario.

A major contributing factor is the use of detail correction that adds a very definite, hard, non-motion blurred black or white edge around any areas of medium to high contrast. In the case of a pan that hard edge is going to step uniformly from one position to the next, it won't have any motion blur and it will increase edge contrast compounding the images judder. The PMW-F3 although it uses the same sensor is less prone to this effect as it has a more sophisticated DSP and uses less detail correction and more aperture correction for image sharpening. Aperture correction blurs with motion as it is a type of high frequency boost.

You also need to consider the results of watching 25fps video on a computer monitor typically running at 60hz. You will get judder as 25 does not go into 60 evenly, this helps explain why this "issue" is getting more airtime in Europe than in the US where 24P with pull up to 30P is common and of course 30P will display on a 60Hz monitor with no additional problems.

So, and I have not tried this, I would suggest turning off the detail correction circuits if you are shooting high contrast images. It would also be interesting to compare similar pans at different speeds with some gain added to see if that helps.

It's not a camera fault, more likely a result of a very clean, detail corrected image. Even an EX1 or EX3 will do similar things if your detail settings are too high.
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Old July 4th, 2011, 07:34 AM   #12
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Re: 25P juddering motion.

Hi Alister,

Problem is, the manual detail adjustments on the FS100 are not well explained in the manual.
Do you have any idea, how to reduce stutter effectively without getting negative results like losing resolution?

When I use 1/25 shutter speed on my GH2, I get the usual smearing image when panning, but the FS100 looks not really different when you compare 1/25 and 1/50. It just (as you said) "stays" too sharp while panning.
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Old July 4th, 2011, 10:00 AM   #13
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Re: 25P juddering motion.

Has anyone noticed this in 24p? Is the AF100 going to be better than the FS1000 hand-held because of this?
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Old July 4th, 2011, 12:43 PM   #14
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Re: 25P juddering motion.

It is possible to shoot 25P with the FS100, without the picture getting ruined by juddering.

Steve and Alister explains weary well what is going on. All my findings have proven that there is nothing wrong with the camera, we are just going to learn to use it.
On the other hand Sony can help us on our way in a future firmware update, by giving us more control over detail and maybe doing something about the problem in the firmware itself!!

The detail settings give some opportunities to control detail. It is not as comprehensive as in a full pro camera, but some adjustments can be done. You have to turn on manual settings before they have any effect! If you leaves it in auto some unknown detail correcting is going on and you can only control one parameter from -7 to +7 (page42 in the user-manual).
The user-manual describes what can be adjusted but it is going to take some testing to get the best settings for 25P.

Shooting techniques is a major factor. You canīt bash the camera around as in i mode.
There are many articles on the web. Read some of them.
One here DVuser: The Art of Shooting Progressive
Nigel donīt like the FS100 but that does not mean his thoughts about shooting 25P is wrong!!
Go and see some movies and watch how they are shot!!!

The suggestion by Alister to use gain and thereby reducing the problem, seems to be working!
I went out the other night and shot some tests. I were using +9db and made waking shots, pans and tilts. No juddering at all. Some of the shots were of an well lit Church making the picture fairly contrasty. No whites though. I have found white to be the worst color to make judder..

Why the FS100 is more juddering than other cameras is class, as Alister explains, because it gives a much sharper picture. Many who says “ my other camera donīt have this issue” are referring to a camera with a waaayy softer picture. A lot of the comparisons is done with Panasonic models with a native resolution of just 960x540 pixels!!

By the way turning the detail way up on my f330 gives also a juddering picture in 25P.
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Old July 4th, 2011, 12:55 PM   #15
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Re: 25P juddering motion.

Quote:
Originally Posted by Brian Bang Jensen View Post

Why the FS100 is more juddering than other cameras is class, as Alister explains, because it gives a much sharper picture. Many who says “ my other camera donīt have this issue” are referring to a camera with a waaayy softer picture. A lot of the comparisons is done with Panasonic models with a native resolution of just 960x540 pixels!!
Nope, the GH2 resolves over 820 Lines. Thatīs a lot more than the FS100.

But as you and Alister said, it must be solved with the detail adjustments.
Iīm getting the camera next week and first thing I do will be messing around with the detail options.
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