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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Exposing correctly

Jamie Havill

Jamie Havill

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Hey guys,

I recorded my first ever Red footage recently (in prep for my short in February), and have got around to looking at it just now. We only recorded a few minutes and we were limited to 2K @ 2:1 as we only had a Sony 306x CF card with us.

We were given the Red Pro 18-85mm and the room was quite dark. After all my time spent on the forums and such I exposed as best I could given the light conditions. I left the camera at 320 ISO with the lens wide open at T2.9.

This is a frame grab from one of the clips. It's taken in Premiere Pro CS4 from the R3D and is accompnied by the histogram/RGB parade/vectorscope etc.

It was my understanding (from reading and watching a video with Tod explaining exposure) that when exposing for Red, it's best to keep the majority of the detail around the lower mid section of the histogram (darker than you would expose for video) to preserve highlights. This would give you more latitude in post and give a nice organic image when grading.

From what you can see, does this look correct? The image is straight off the mag, loaded into Premiere and a screenshot taken with no grading, no adjustments of any kind.

Your thoughts are appreciated.

Jamie.

qqof8i.png
 
We didn't have a meter unfortunately. This was a get in, get it done, and then get the hell out kind of deal. I had absolutely no control over anything except trying my best to expose with what I was given.
 
Hey Jamie,

it looks correct, but you missunderstood the exposure advice a bit.

What you should do is expose as much as possible to the light side of the sensor (histogramm), because then you can pull down and get rich blacks and a low noise floor.

You should stop down though to avoid clipping highlights (check traffic lights/false colors). The advice is rather have a bit of a darker image than overexposed (GONE) highlights.

There's a very informative thread going on in Recon at the moment about exposure. Follow it!
 
The thing to remember about protecting highlights is that it's OK to let small areas clip if they are unimportant -- for example, you would not bias an exposure to hold detail in the filament of a flashlight in a night scene where someone was going through a dark room with a flashlight.

So in your example, you have two types of highlights -- there are the highlights of the objects in the room including the face, and there's that really hot window in the background. What's out that small window is not important enough to cause you to underexpose everything else to achieve some sort of balance, so in this case, I'd ignore that hot spot and expose for everything else in the frame.

But all of this assumes you have enough light or a fast enough lens to make a choice in exposing the shot. It seems in this case, you were just setting the lens wide-open and hoping you had enough light.

On the other hand, it may be correctible without too much noise being introduced.

My suggestion is to light a test subject and a chart (something with black, white, and 18% grey) to the middle of the lens, like f/5.6, and then shoot some over and underexposure versions in one-stop increments and look at the waveforms and histograms to see how it plots out.
 
Jamie Havill said:
We didn't have a meter unfortunately. This was a get in, get it done, and then get the hell out kind of deal. I had absolutely no control over anything except trying my best to expose with what I was given.
Click to expand...

Edit after David's post... agree.

Try some quick grading to see what you have. You might be surprised with this one. Open in REDAlert! (or REDCINE-X). Set Color Space to CameraRGB, Gamma to REDlog and you will see pretty quickly what's there as the shadows will be opened up quite a bit and all noise exposed. You can either pull down the blacks with a curve here or try a quick grade in REDspace or REC 709.

Exposure is a learning experience with RED. What you can do with what you have in post confirms (or not) your exposure/lighting decision. Lots of practice here will only be a good thing. Shoot... grade. Just make sure you do your footage justice by getting to know one of the apps well... or hand it over to someone that does.

Jim
 
Thanks guys.

@ Joel - I'm checking out that thread now.

@ David - I genuinly thought I was exposing that shot OK. There was a Zeiss T1.3 I could of switched to pretty quickly, but I thought the exposure with the Red Pro looked OK. Would you say that shot is definitely underexposed? If so, severely?

The thing thats confusing me, is that I watched a video with Tod from Red who advised really going to town on protecting the highlights, and said correct exposure for Red is a lot darker than what you might be used to. I've also read quite a few discussions advising keeping the majority of detail around the 0.4 mark on the histogram. I know I'm probably holding too much weight on these statements. I'm just curious as to say, how many stops over what I did you would go, and exactly how under exposed that specific shot is for a successful clean grade?

Jamie.
 
Jannard said:
Edit after David's post... agree.

Try some quick grading to see what you have. You might be surprised with this one. Open in REDAlert! (or REDCINE-X). Set Color Space to CameraRGB, Gamma to REDlog and you will see pretty quickly what's there as the shadows will be opened up quite a bit and all noise exposed. You can either pull down the blacks with a curve here or try a quick grade in REDspace or REC 709.
Click to expand...

Cheers Jim, I'll do that right now.

Edit: Do I set both the colour space and gamma space to REC709 for the grade?
 
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Jamie Havill said:
@ David - I genuinly thought I was exposing that shot OK. There was a Zeiss T1.3 I could of switched to pretty quickly, but I thought the exposure with the Red Pro looked OK. Would you say that shot is definitely underexposed? If so, severely?
Click to expand...

No, just mildly. I can't really say it's a "wrong" exposure either, just that you had more leeway to give your image more exposure if you ignored that window in the background and just let it clip.

Yes, RAW images can sometimes seem a bit on the dim side because of highlight protection, but in this case, ignoring the hot window again, your other highlights were exposed well below any chance of clipping, even that white piece of paper behind the person is hardly close to being clipped. I'm not sure if I'm reading your charts right, but it looks like that white sheet of paper on frame left is only hitting 40 IRE?

But as Jim suggested, it probably will color-correct fine as long as you don't lift the shadows too much, which would reveal noise.
 
Jamie Havill said:
Cheers Jim, I'll do that right now.

Edit: Do I set both the colour space and gamma space to REC709 for the grade?
Click to expand...

I'd keep the color space set to CameraRGB for now. It will feel a bit under-saturated.

Get to know one of the RED apps as best you can. Experiment with settings, curves, matrices... the more you know, the better decisions you will make going forward. And if you can make the footage look good... a trained professional won't have any problems.

This is simple stuff... if you protect every highlight in every shot, you will run the risk of noise in high contrast. If you always make sure you have no noise whatsoever, you run the risk of clipping some highlights (again depending on contrast). These are the goal posts. Understanding how to stay in between through lighting and exposure is the puzzle to solve. Most of the time it is pretty easy. High contrast scenes are where you have to put on your thinking cap.

Jim
 
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Jannard said:
I'd keep the color space set to CameraRGB for now. It will feel a bit under-saturated.

Get to know one of the RED apps as best you can. Experiment with settings, curves, matrices... the more you know, the better decisions you will make going forward. And if you can make the footage look good... a trained professional won't have any problems.

This is simple stuff... if you protect every highlight in every shot, you will run the risk of noise. If you always make sure you have no noise whatsoever, you run the risk of clipping some highlights (depending on contrast). These are the goal posts. Understanding how to stay in between through lighting and metering is the puzzle to solve.

Jim
Click to expand...

Thanks Jim, I really, really appreciate that.

I understand the difficulties, I'll start learning to navigate them properly.

I'll spend a lot of time with Redcine-X. I've just purchased a HP dreamcolor, grading this was the final straw for my TN panel based samsung.

I'll spend some time doing a grade, don't expect much, but I'd appreciate peoples thoughts later on what I do.
 
Jamie Havill said:
Would you say that shot is definitely underexposed? If so, severely?
Click to expand...

Odds are that's a usable image with some grading.

As Jim said, get REDCINE and start playing around. I bet you have something decent there. But, having said that I still think it's underexposed for the person in the foreground. That just means a little more noise in the shadow and the likelihood some colors have shifted or won't be as vibrant as they would have been with more exposure.

As David says, exposure is a choice. It's difficult to claim a "right exposure" for any given scene. This is a scene that I probably would set so highlights in the window would blow out in trade for more information in the room.

It's not as simple as hold all the highlights or your histogram should like this etc. Out in the wild it's just not that easy. RED is pretty forgiving to underexposure, but I don't believe it's a best practice to underexpose. It doesn't really show off what the camera is truly capable of.
 
BTW... it is great to have David around here. Having a trained professional share his knowledge is a luxury that shouldn't be taken for granted. All of us at RED appreciate the unselfish effort...

Thanks David.

Jim
 
I shot one of the first F900 features in Los Angeles back in 2000, and the post house had never handled a 24P HDCAM project yet, so they were helping us out as a learning experience for themselves too.

Well, the movie was about karaoke bars and I got a note from the post house that my first day's work had clipping going on -- I looked at the shots they were talking about and the were of a karaoke singer with stage lights (actually some Dedolights) behind his head, flaring the lens intentionally. The post house was concerned because the bulbs inside the stage lights were clipping!

My point is that often something gets clipped in a shot unless it is completely devoid of bright areas and specular highlights. If a car drives by in the shot and the sun momentarily glances off of the windshield, well, that sun flare will be clipped. A flashlight pointed into the lens will be clipped. Even in this underexposed test that Jamie posted, parts of the window are clipping.

Clipping just means that the object is so overexposed that it becomes white and featureless, without detail. In small amounts, that's OK, especially if the viewer is not expecting to see detail in that area anyway. It's only distracting when the clipped area looks unnaturally devoid of texture and detail. A clipped white shirt collar on someone wearing a dark suit, no problem generally, but someone wearing a white shirt with no jacket in a medium shot, well, it can get ugly if the whole shirt is clipped and you lose texture in the fabric and even some of the folds and wrinkles disappear in the overexposure.
 
I tinkered for a while and got this. I used CameraRGB for the colourspace and RedLOG for the gamma space. I crushed the blacks. Things are a bit dark, but I don't want to bring the image up anymore because of noise.

Any input is appreciated as usual.

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Jamie, I remember that thread. I think mine was the first reply, I said the video was junk and should be ignored. I remember you saying how much you had learned and thought this would be the outcome. That is both the benefit and the problem with internet forums.

Anyhow, you've had some great advice in this thread from people far better qualified than me to offer help, but here's a tutorial that should get you in the right direction:

http://www.luminous-landscape.com/tutorials/understanding-series/understanding-histograms.shtml

Also, look at the tutorial on curves.

Your shot is by no means beyond saving - that's the beauty of RED. To improve it, you need to adjust the mid-tones. The node in the middle of the gamma curve should be higher than the linear line, this will have the effect of "pushing" the exposure in the right direction. Have a good play with all the settings, I'm sure you'll get something out of it.
 
When I was first getting used to exposing the RED and working with DPs who hadn't shot with it much, there would tend to be some panic about highlights clipping. But then you realize, that a lot of times those areas clipping are not necessarily important to the shot, perhaps because they are specular or just not very important information when the better option is to just let them go and get a better overall exposure. Of course, with a much more controlled set, and tools that allow you to control every last pixel of the frame, you can start to alleviate these hot spots a lot of the time. This is the art, knowing when to let something go for the better of the shot. Sometimes meters alone can't tell you the whole story. You need your eyes too, and you need to make decisions based on what's important to you. If that window was an important part of your shot, then it would be necessary to light your subject appropriately to balance the scene.

I know it's been said a million times on here before, but as of right now it's the most important piece of advice. Test as much as you can to learn how this camera reacts to various kinds of light and what the color/gamma spaces do to affect your images. Once you get a feel for it, you'll be much more confident in your lighting decisions and exposure will become second nature. I've had the opportunity to see some great imagery shot with the RED. That's had a lot to do with the talent behind the camera, people that know how to light. Once they adapt to the RED's way of reading that light, they can take full advantage of everything the camera has to offer.

Kudos for shooting this test and beginning the process of trying to understand the sensor. Keep shooting. I'm learning new things every time I use the camera.
 
There is certainly more to be found in this image... a little noise is not the end of the world. Everything is a balance. Take you foot of the brake a bit. If you grade to the look you want and find that you have a bit of noise because of your exposure... use some NR. There are a lot of tools in the bag. Don't be afraid to use them. Using NR is not a sin. If this is the look you want... then ignore everything else. Your call...

Jim
 
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