Noise

[Agenda Productions]

Hi,

I have some trouble when shooting with video when i try to go for a high contrast ratio. I recently did a shoot where is had a 1k Fresnel immatating a desk lamp diffused slightly and the other side of his face very dark. The look was there, but, slightly noisy no matter what i tried.

I believe video can handle 4:1 ratio, is this correct?

But i am after any tips to get that darkness on video without getting noise. What is the best method, do you try and close the apperture right down or flood heaps of light in and turn it up?

Thanks.

James.

 

[David Mullen ASC]

The noise shouldn't change if the f-stop used is correct for the light level. In other words, if you light a scene to f/11 and shoot at that stop, or light a scene to f/2.8 and shoot at that stop, the amount of lighting hitting the CCD is the same. It's just that you may get more contrast at higher light levels because you are overpowering any natural ambience filling in the shadows.

The gain level affects noise. Some consumer cameras, once you get to wide-open on the lens iris, will automatically start boosting the gain so make sure your gain is set manually at 0 db and stays there. Some cameras even allow minus gain, like -3 db, to reduce noise even more.

Gamma processing, especially "black stretch" or black gamma, affect the noise of the shadows if set to create a low-contrast image. You would be better using more fill light then instead to lower contrast.

Sometimes you can improve the appearance of noise by not exposing too darkly for dark scenes, but exposing a little more normally and bringing down the image slightly in post.

Some cameras are just inherently noisy.

 

[laurent.a]

Hi,

As David sys, the settings are very important. But if you duidn't make any chage, one should think the "factory" setting should be fine, unless it is a cheap amateur camera.

Can you tell us what camera it was, if you have an idea of the settings you used etc.

Also, did you notice that noise on a monitor on the shoot, or on the tape afterwards, or even after editing (a bad tape or desk or even editing can provide noise...) ?

 

[Agenda Productions]

Reply to Noise on DV

Reply to Noise on DV

The Camera was an XL1s- shutter 1/50th, .5 Wide angle lens. (not sure of the stop value, stupid. i know!)

the setup,

1k Redhead diffused 1/2 spun to the right of the frame immitating a desk lamp. The lamp globe was replaced with a 25watt so not to blow out. I exposed for the face of the subject. It looked exactly how i wanted it, 1/2 stop overexposed on one side of his face and heavy contrast ratio on the other side, and therfore very dark. It looked like the practical was creating the light and gave nice detail. Adding to the problem it was a test shoot and we did not have a sufficient monitor. There was slight noise on the blacker/blackest parts of the frame.

I understand i probably did not have it to the right stop value, but, after last year a few of the shools short films i watched did have noise throughout the frame. Is the reason for this usually what David said, wrong stop value to, which brings me again,

M. David Mullen: "The noise shouldn't change if the f-stop used is correct for the light level. In other words, if you light a scene to f/11 and shoot at that stop, or light a scene to f/2.8 and shoot at that stop,"

how do you know, besides judging by eye, what to put the stop value at on the camera. Do people have certain scenarios that they light too, like, if there is a 2k diffused fill and a 1k rim light i will set the stop to 5.6? or mainly by eye or with zebras?

The main problem was that i was confident in the look and lighting, and also was handheld scene, so, i was not looking at the monitor. Overal it was a test scene and nothing was lost but i was wondering can you almost get the kind of darkness in a scene on video as you can on film?

James.

 

[laurent.a]

Of course blacks are not as beautiful with video as with film, but one consider that video has more problems with highlights (saturated) than with blacks, in general.

It sounds like you should improve the way you set your iris as well as configure correctly your monitor and examine your light correctly on the set, by eye, and with the monitor.

 

[David Mullen ASC]

It would be easy enough to shoot a test. Light a scene to f/5.6 the way you want it to in terms of being dark & moody, shoot it, and then add a ND.60 to the lens and shoot it at f/2.8 and see if anything changes other than depth of field. Just make sure EVERYTHING is on manual-only (gain, shutter, iris, WB, etc.)

 

[Agenda Productions]

Thanks David,

Ill try it and post some stills.

Regards James.