Ex-1: reputedly-proverbial noise issue

[Marius Sørli finnstun]

I appreciate it! 🙂

[Alister Chapman]

It’s important to understand how noise works. The amount of noise and grain in an image remains constant whether the image is fully exposed or not. Say, for arguments sake, the noise in the EX is 14mV, that would represent just 2% of the total video signal (700mV is peak white). Now if your image is very dark and is only reaching a peak of 100mV and you add to that the 14mV of noise it is modulating or varying your picture by 14% which is going to be quite noticeable. However if your image is brighter at say 600mV then adding 14mV of noise to that means the signal is only being modulated by 2.3% which is hardly noticeable. This is why a well exposed image will appear to have less noise than a dark one. So if you can lift the overall brightness of an image you will have less visible noise.

On the EX cameras the Standard Gammas have a little more noisy than the CineGammas. Standard Gamma 1 is much noisier than the others.

Alister Chapman
http://www.xdcam-user.com

[Rafael Amador]

The post of Alister explain as well why is important don’t to crush the Blacks in camera.
Just lowering the Blacks in post would be enough to get rid of the most part of the noise in the dark areas.
rafael

http://www.nagavideo.com

[David Burch]

“I have found on the EX it is noisier at F1.9 at -3 db gain than at F4 with 6 db of gain.”

Really? That surprises me. I normally try to keep my iris as open as possible because, in my opinion, the stock lens on the EX-1 and EX-3 looks much better the more open it is. I have found that anything more closed than F8 tends to start looking soft. Also, I typically shoot for as shallow a depth of field as possible.

I have actually been very pleased with how these cameras handle low light, and have not found them to be excessively noisy at all, except for in certain conditions. One thing I have found to be helpful in minimizing noise is to try to shoot in light that has a higher color temperature. Typically, in sub 3000K lighting the camera has to compensate by boosting the blues, which is where a lot of your noise can come from. There are some good PP settings floating around on the web that help minimize this, but if you have control of it try to keep the color temp up if possible.

Gamma settings can play a huge role in noise as well, as they can essentially be applying gain to the image even when the camera is set to 0dB.

If it’s true that the camera is noisier at F1.9 in -3 than at F4 in +6, then something strange is going on. The lens aperture should have nothing to do with noise, and if an image is correctly exposed at F1.9, the sensor should have enough light to minimize noise. What matters is how much light is hitting the sensor, not how big the aperture is.

That said, I never use auto iris, and a lot of the scenes that I shoot would probably cause the auto iris to overexpose. (I rarely have any control over lighting, as most of what my company shoots is live events.) Typically. my rule of thumb is to try to keep the iris as open as possible, which usually means my gain is set to either 0 or -3, and so far I have been very happy with the results 🙂

[Robert Clegg]

Hi All,

Sorry to hijack this thread and hopefully it actually compliments this – can anyone take a look at the footage we captured yesterday. Shot by pro lighting cameraman on EX1.

https://www.mediabank.co.uk/Sample_H264.mov

There is so much noise in it – and I am befuddled what is causing it. Obviously this is compressed H264 but it looks very similar to the RAW footage when viewed through the viewfinder of our EX3 and through XDCAM Browser. Its in his jacked you can see it most.

Anyone got any idea what has caused this. We shoot on EX3’s all the time and have never seen noise like this before. I believe the EX1 is same camera fundamentally so not sure what I am seeing…

Thanks for any help you can offer as I am little concerned about what we have got here

Thanks

Rob