EPIC Noise/Grain

[D Fuller]

Hi Lee,

I have just looked at the R3D and agree with John's analysis.

In my view it can be saved... I have reset all the original metadata and (roughly) tweaked it - once downsampled to HD it should be usable.

I have zipped a snapshot and an RMD with my tweaks.

I don't think the OP's question was "Can it be saved?" (He's already running it through Neat Video noise reduction.) Though I agree with John's analysis too.

But I thought he was asking why it happened in the first place. I really do suspect something like the scenario I described above, where the xmas bulbs at the left of the frame gave him clipping in the histogram and fooled him into underexposing. Not a camera issue, but an operator error. It's easy to see how that could happen. They're not even in the room, and there's the white shirt and flags to protect from clipping. Who'd notice the xmas bulbs outside the window?

[Tom Gleeson]

I have seen some tests Jim Hare shot and it was clear that compression was adding noise. Same shot was recorded at varying compression rates and there was no doubt the cleanest blacks were at 3:1. The differences on a normally exposed shot were hard to see unti you zoomed in. But if you window the sensor, underexpose or push the sensor hard high compression will only aggravate the noise.

[John Marchant]

3k, very warm colour temp, underexposure, all of these are bad for the picture inherently, but Tom's right also that the same shot at a better compression rate than 10:1 would look better.

I feel that the EPIC's redcode can sometimes have a hard time compressing the inherently random noise down in the shadows. If you go pixel peeping you'd be surprised how often it occurs, but critically it usually occurs NOT to the detriment of the visual. Sometimes a combination of other bad factors like this will put the spotlight on the compression in a way that isn't flattering.

Always more to learn to get the best from even the most forgiving of systems :)

[Lee Dashiell]

Thanks for the help John. I agree with everything you've pointed out. I wasn't in a situation to bring in additional lighting here and the lens was wide open so I should have lowered the compression. I shot at 3K which is very unusual for me but I thought it would be better to go ahead and push in to what would be my widest shot on the sensor. I was on a 200mm lens at 2.8. I was able to correct the image well enough to make it work but I still don't recall my RED One MX pushing this much noise into the image. I think that the 2200 kelvin may have been what hurt me the most, it's hard to say.

Thanks again for the help.

[Gunleik Groven]

It means he's shooting it as if his ISO 200. I thought about doing that, too. But then I realized I just paid $40 grand for a camera that claimed to shoot at ISO 800. I stood in denial. :-)

well, everything is calibrated/zeroed at 320ISO. That is not to say te cam is 320, but that you still can trust your meters down to 320.

You lose all highlight headroom that way, though

[David Battistella]

You lose all highlight headroom that way, though

Highlight headroom can always be preserved with the iris ring on the lens...:)


David

[David Battistella]

@Lee

Lee,

If you would like me to send you a copy of the snapshot with the RDM I created, I would be happy to help you out by e-mailing it to you.

Pushing the ISO to 1000 is always going to increase noise in the black areas, but with a few easy post strategies you can get a really good result from this footage, probably without using NEat video.

David

[Gunleik Groven]

Highlight headroom can always be preserved with the iris ring on the lens...:)


David

THAT depends highly on shooting conditions. That's basically why it is good to keep some headroom.
The other reason (on R1 M/MX and just about any other camera I have tested BUT the epic) is that sensors seems to start to behave quite flimsy and un-nice in the last stop or two before clip.
Even though their mathematical/theoretical precission should be at the best at those last stops.

G

[David Battistella]

THAT depends highly on shooting conditions. That's basically why it is good to keep some headroom.
The other reason (on R1 M/MX and just about any other camera I have tested BUT the epic) is that sensors seems to start to behave quite flimsy and un-nice in the last stop or two before clip.
Even though their mathematical/theoretical precission should be at the best at those last stops.

G

Agree. But it's parlour tricks. ISO, HEadroom, whatever. Knowing how and where the sensor reacts is important, but at the end of the day, it's how much (or little) light you let hit the sensor and that is always controlled by aperture, nothing else.

David

[Gunleik Groven]

Ouch David... :)

I regularilly controll it with filters, because I want to keep the aperture at a given stop to controll DOF, be it deep or shallow.
If I shoot for stills, I use the shutter quite a bit to keep the aperture.

Only when desperate, I use the aperture to controll exposure (by either shutting down more or opening up more than I would like to for compositional reasons).

Aperture is part of image carracteristics. Filters and shutter are parts of light/exposure controll.

Just my take on that. I think both our approaches are relevant, but aparture controlls a lot more than exposure...

SOrry to derail the OT... :)