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-   -   My camera is suffering from a serious skin condition. (https://www.dvinfo.net/forum/sony-nxcam-nex-fs700-cinealta/511843-my-camera-suffering-serious-skin-condition.html)

Colin Elves November 2nd, 2012 04:35 PM

My camera is suffering from a serious skin condition.
 
Hello all,

Sorry about the slightly odd title - I hope it might draw some interest.

Basically I'm trying to work out if my FS700 has a problem or not. Specifically with what appears to be noise in middle-shadow/middle-black tones.

I say appears to be noise because I am fairly certain it is not simply noise, as it is not present in the near black dark areas - but only in tones slightly lighter than these. You can actually see the noise spike as you stop down, then disappear as an area moves towards black. The problem gets worse if you go into super-slo mo, worse still in speeds above 240fps.

The general effect is to make surfaces appear like 'they're fizzing'. It's a bit of a problem as I've had two clients complain about it (producers, not cameramen/editors: so it has to be pretty bad for them to notice!) - one of which has basically described the footage as unusable.

I've noticed that it is worse in profiles that raise the black level (e.g. Noah Yuan-Vogel's / the AB_Nex Log) and improves somewhat (but doesn't disappear) if you reduce the black level and in Profiles that reduce the black level (e.g. Alister Chapman's fla / AB_Range). In fact, the only true solution I have found is to reduce the black level and over expose: as mid-greys are noise free, you can then bring them back down to blacks cleanly. But in this instance you are losing a lot of DR. Without pulling down the blacks I still seem to get a little noise in middle-greys.

I'm wondering if it is a codec thing. More importantly I'm wondering if it is just my camera (and so needs to be sent back to Sony) or if it is a 'feature' of the FS700. So I'm wondering if anyone else has noticed this problem?

Thanks,

Colin Elves
DP/Steadicam Op, London
Colin Elves - Director of Photography and Steadicam Operator

Phillip Palacios November 2nd, 2012 05:40 PM

Re: My camera is suffering from a serious skin condition.
 
Haven't noticed this on mine. I prefer how Alister's Flat profile handles blacks and greens. Can you post an example? Does the noise stay the same after color grading?

Colin Elves November 3rd, 2012 04:11 AM

Re: My camera is suffering from a serious skin condition.
 
For reference - here's the test a client shot (the guy who says it is unusable) that exhibits the problem:*
- from 45sec onwards, in the guy's dark jeans.*

This is after grading, grading doesn't remove the noise, (unless you crush the blacks much it drops off the bottom) it just changes the tone of it.

Phillip Palacios November 3rd, 2012 01:10 PM

Re: My camera is suffering from a serious skin condition.
 
Can't tell much from the vimeo compression. Which leads me to believe the one who said it is overstating the problem. Like someone said at the "other" site where you posted this, the exposure wasn't quite right either, which can compound noise issues. If delivery is the web, its basically indiscernable with web compression. Broadcast folks can chime in for their opinions.
p

Matt Sharp November 3rd, 2012 01:50 PM

Re: My camera is suffering from a serious skin condition.
 
That looked pretty great to me.

Finn Yarbrough January 5th, 2013 08:04 PM

Re: My camera is suffering from a serious skin condition.
 
I have heard from many other people that super-slow-motion on the fs700 produces aliasing. Perhaps noise is part of that?

I agree with the others, though: it's hard to see what's wrong with the video, other than internet compression and the fact that your color grade is pretty flat. It should come as no surprise that raising the black pedestal will create more noise and "milkiness." "Unusable" is not the right word, though. It sounds to me like somebody is trying to intimidate you.

What did you use to grade? When I get too aggressive with my grades in FinalCut, I get a kind of flickering noise in certain areas, particularly if I try to grade "selectively," you know, trying to pinpoint a certain color and saturation.

Just crush your blacks a little, and lower your midtones by a hair. I would be very surprised if that doesn't fix it, and if that makes the whole picture too dark, then it was probably a little underexposed to begin with.

Good luck!

Will Salley January 5th, 2013 10:32 PM

Re: My camera is suffering from a serious skin condition.
 
I doesn't occur with my camera either. The only unacceptable levels of noise I have noticed are when ISO is above 6500, or chroma levels (particularly red) are boosted well above default levels.

I shoot to both the internal codec and out to ProRes. A comparison of the footage reveals just how good the NXCAM codec can be, although it is less forgiving, as expected, with high exposure, fast movement, and subtle gradiations in the dark areas. Not so much with noise, but banding.

Matt Davis January 7th, 2013 10:37 AM

Re: My camera is suffering from a serious skin condition.
 
With apologies - I'm going out on a limb here...

1) I have seen this before but on my Canon DSLR footage when I pumped up the blacks too much then had to drag them down in post - shooting flat where one shouldn't.

2) Alternatively, I may be barking up the wrong tree but it also looks a teeny bit like 'denoising' thing in-camera that's kicking in too early. Maybe the gain's been set a smidge too high for the shot, but again this 'boil' could be the 'pulled pork' effect from rescuing a shot in post.

3) The aliasing on FS700 slomo (100-240fps) tends to exhibit 'twinkles' on areas of detail rather than this sort of pattern.

Alister Chapman January 7th, 2013 09:24 PM

Re: My camera is suffering from a serious skin condition.
 
It could be many things. It might be too much gain in the camera, it might also be your workflow and how much your pulling and pushing footage in post. Another factor may actually the quality of you post production decoder and the filters you are using. Some applications do a much better job of decoding and then processing AVCHD than others. I always try to work with a project that uses a 10 bit codec during post production and grading. You want your timeline set to 10 bit so that any renders and filters are applied in 10 bit. Grading 8bit to 8 bit is really not a good thing to do Why rendering form 8 bit to 8 bit can be a bad thing to do. |


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