How to expose to minimize noise when shooting against black backdrop?

[Joel Arvidsson]

When youre shooting outside or in a bright studio setup there no problem with visible noise. But Im not sure what is the best way to shoot a person against a black backdrop. First do you like to go down a little in iso as you tend to open up the iris more and lower the noise that way. Should you overlit everything to kill noise. Or perhaps you just try to crush the blacks in post. I not a big fan of the crushed black look as it tends to give everything a harsh look.

I have only done a quick test on this where I did not care so much how I lit the subject (se picture). The picture is only noisy in the "unlit" black area. Perhaps the problem with this image is that I had the backdrop only 1.5 meters behind the subject. So It got a little light on. I used a backdrop I use to block light with since it was already mounted. Next test I will put a backdrop further away wich would make lighting much easier.

If zoom to your black backdrop to cover the camera. Are you suppose to have the "noise meter" go full or?

Thanks for your help.

 

[Sean Talbott]

I assume that shooting ISO's in multiples of 160 will do some of the trick. Try sticking to

160
320
640
800

I'm not sure, but I'd bet going past 800 you'll start to see the noise become more and more pronounced. Hope this helps a bit.

 

[Mike P.]

I assume that shooting ISO's in multiples of 160 will do some of the trick.

Sean, I think this only works with Canon HDSLRs since they use push and pull methods to hit the interim ISOs values. I don't think digital cinema cameras do that...

Joel, how do you feel about the results at an ISO of 320 or lower? The reason RED recommend 800 is because that is the highest ISO with an easily workable signal to noise ratio, meaning when you expose for 800iso, you're automatically protecting as much high-light detail as cleanly possible. That said, I think the sensor is actually rated for 320/5600K for cleanest possible results. If you were using tungsten lighting you're going to be stressing the sensor more than daylight balanced lighting, so you'd notice more noise as well (especially in the blue channel of the blacks.)

May I ask what you dislike about crushing the shadows and getting them to 0IRE? I was under the impression that it's essentially par for the course, unless you're doing something specific for a "look".

 

[Sean Talbott]

Yeah Mike you're probably right, it makes complete sense that a professional tool like the Scarlet not be limited like HDSLR's.

 

[Trevor Meeks]

ISO is JUST METADATA... remember that! Multiples of 60 rule is for HDSLRs, not RED. 800 is the sensor's native ISO, correct? Expose as best you can at 800, at least that's what I've read/been told.

 

[Kim Frank]

I not a big fan of the crushed black look as it tends to give everything a harsh look.

I'm not sure, why you would want to shoot against a black background without grading it black. I'd say, if you want a lighter colour for your BG use another BG.
As it was said, ISO is just Metadata and RED Sensors are rated at 800. With digital Cameras you want to stay above the noisefloor, for shadows with detail. Everything without detail like a black BG, in my Opinion, feel free to hit the noise floor, because you'll want to grade it black.

 

[Gunleik Groven]

I'm not sure, why you would want to shoot against a black background without grading it black. I'd say, if you want a lighter colour for your BG use another BG. (...)

These are wise words...

If you want black, shoot black

 

[Jack Shanahan]

I think the native ISO of the Scarlet is 320. If you go into ISO 320 and switch between RAW and normal (not RAW) view the histogram does not change. However if you are @ 800 and you switch between RAW and normal the histogram totally changes.

Just my 2c...

Jack

 

[Gunleik Groven]

What is "native" is measurable.

What is "reference/callibrationpoint" is 320 for sure.

 

[Kim Frank]

I think the native ISO of the Scarlet is 320. If you go into ISO 320 and switch between RAW and normal (not RAW) view the histogram does not change. However if you are @ 800 and you switch between RAW and normal the histogram totally changes.

Just my 2c...

Jack

I have to admit I haven't worked with the Scarlet or Epic. I was assuming it was the same Sensor as the RED MX and Greame clearly stated that it's native ISO is 800.
On a side note, I'm really missing a comperison Test betwenn Scarlet and Epic or Red MX -- or did I actually miss it? Somehow I get the feeling, because of the Scarlet footage I've seen so far, that they don't quite match - maybe I should say yet, because of possible firmware upgrades.

 

[Gunleik Groven]

@ Kim

There can be quite noticeable differences on Epics too, when they are of different batches.

 

[Jack Shanahan]

What is "native" is measurable.

What is "reference/callibrationpoint" is 320 for sure.

Gunleik - what does that mean exactly?

Thanks!
Jack

 

[Jake Wilganowski]

320 is native to reiterate. 800 protects, the histogram proves this, don't know why it's debated...

 

[Jack Shanahan]

320 is native to reiterate. 800 protects, the histogram proves this, don't know why it's debated...

I'm personally not debating - just inquiring myself as Im really still new to RED.

Can you please explain how moving up on ISO protects the highlights? Im still trying to wrap my head around that one.

FWIW ive been reading these forums 2-3 hrs a day since nov 3 and I have yet to find an explanation I totally get.

Thanks in advance...

 

[Jake Wilganowski]

ISO is not like any other traditional video camera. It only affects the monitoring path, not the recorded data. So if you set it for 800 it looks brighter on the monitor which may cause you to stop down therefore automatically protecting highlights more since by stopping down you are affecting the recorded data. Listen to this next part, it's very important: if you leave your iso at 320 always and use your histogram, what you are recording and monitoring will match.

 

[Jack Shanahan]

ISO is not like any other traditional video camera. It only affects the monitoring path, not the recorded data. So if you set it for 800 it looks brighter on the monitor which may cause you to stop down therefore automatically protecting highlights more since by stopping down you are affecting the recorded data. Listen to this next part, it's very important: if you leave your iso at 320 always and use your histogram, what you are recording and monitoring will match.

Shooting @ 320 and monitoring the histogram and goal posts sounds like sound advice - I feel like shooting at 800 to protect the highlights one could conversely end up getting noise in the shadows...

 

[Jake Wilganowski]

If you know the cam well, you can do whatever you want of course to use the full potential of raw and monitoring different iso. But for those new to the cam, it seems easiest if they can start with the true iso, which is 320. It confuses people who aren't familiar with raw I think to say 800 is native, it's not, it's officially recommended, but not native.

 

[Peter Majtan]

I'm not sure, why you would want to shoot against a black background without grading it black. I'd say, if you want a lighter colour for your BG use another BG.

I think Kim You are misunderstanding Joel. He did not say he does not want (or like) "black" - he said "crushed blacks". Basically he wants black BCKG, but he is wandering how to best light it. If You ETTR and leave some headroom in the blacks to avoid noise - you will have to crash the blacks - which will in return crash the subject too (unless you go to painful secondaries). If You expose the BCKG as black - it WILL be noisy. We have just completed high-end shoot on the Epic in this exact scenario. Our situation was even more complicated as there was a deliberate light falloff on the black floor. Joel actually answered himself - the best solution is to separate the black levels of the subject from the black levels of the BCKG by selective lighting. If there is at least one stop difference between the black levels (use a black chart in the place of the subject if you can), you can then ETTR and leave headroom in the black channel. You will be able to easily isolate the BCKG black levels from those of the the subject and therefore be able to crush them down without noise and without crushing the blacks of the subject...

Just my two yen..

Peter

 

[Peter Majtan]

Shooting @ 320 and monitoring the histogram and goal posts sounds like sound advice - I feel like shooting at 800 to protect the highlights one could conversely end up getting noise in the shadows...

Bingo. I always monitor 800 when in bright situations and 250 when in dark situations. Stick to 320 when is studio controlled lighting...

 

[Mike Lary]

Greame clearly stated that it's native ISO is 800.

Actually, he stated that 800 is the sweet spot and the recommended starting point, but also that "native ISO" has no meaning in relation to sensors.

The ISO setting provides an interpretation of raw data, not a direct correlation. The histogram is not validating an ISO rating, and neither 320 or 800 is "wrong". It comes down to personal preference in choosing. For the OP, I would recommend rating some tests at both ISOs to see if 320 produces cleaner images since highlight protection won't be a concern when the subject is lit properly.