Overexpose = Better Image Quality? | Blackmagic Raw Exposure Test
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- เผยแพร่เมื่อ 10 ก.ย. 2024
- I've reading a lot about film and digital cinema cameras and how overexposing an image can actually improve the overall image quality. So I set out to find out if that was the case with my Bmpcc 6K. I got this guy in October and haven't used it too much so this was an excuse to bust it out and get to shooting. I found out in short, yes. Overexpose especially if you are going for that high key look.
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Hi very interesting test what would you recommend for shooting a documentary in Black Magic Raw such as compression ? Thank you.
I think the biggest bottle neck with that decision is actually the amount of footage you plan on shooting and the amount of storage you have available for the project. Length of project? How many interviews and how long? How much storage do you have available?
Not every project needs to be shot in raw. Especially if you are not going heavy in effects or color grading. 8/1 or 12/1 are sufficient and have a lot of detail still. Do you have the bmpcc? Need to be raw in order to shoot 6K?
There's a reason why cinematographers today hardly ever use this approach. If you know the Log curve of this camera you'll know that as you approach the highlights, the camera compresses the highlight data to reduce the amount of data needed capture the scene. Think about RED raw or Sony x-OCN, they capture images linearly thus using much more data had they not been compressed formats. Pure 4K RAW captured linearly is a monster, that's why sigma fp eats harddrives for lunch. But this is also so you don't have to worry about highlights compressing in the raw data.
But since bmpcc 6k captures light logarithmically, you'll know that as you overexpose and force the majority of the light data into the upper echelons of the waveform, what you're doing is you're reducing the tonal range of your image, this applies to both prores and blackmagic raw since both are encoding the scene logarithmically.
A better strategy is to figure out the scene and your camera's dynamic range. I usually pick the midgray from the scene since i'm used to differentiating 3 gray tones from any scene I shoot. Midgray, upper gray and lower gray. Now match the midgray of the camera to the scene midgray.
This is the reason why the control image has much better tonal range, skintone and overall better contrast. You distributed the scene light data more evenly over the camera's dynamic range.
Edit: Noise is completely normal and necessary in RAW and prores if the camera doesn't do heavy noise suppression. You shouldn't always sacrifice tonal range for much cleaner images. Most pro industry work has noise in the raw data and they clean it in post. If you want to figure out how to keep noise out without overexposing, expose more as you did in in the control in various light conditions and learn how much light your sensor needs at a minimum before noise overtakes the signal. Once you intuitively know your sensors performance, the need to ETTR goes completely away.
Sorry for getting nerdy here but this information seriously helped me out in the past so i'm here to share it to fellow creators
Thank you for this insight Shueibdahir, 🙏
how do you work with the practicals in the bg? On False Colour for me, they are always red, whatever the brightness is set, any advice for the practical lights and exposing for them?
Great question. Depending on your situation practicals can be difficult to work with especially if you can’t control it.
The first thing you have to decide is if it is okay for the practical to “blow out” and be overexposed. If that’s okay then you’re good to go. If that’s not an option then this is what I do.
First: expose you’re shot for the practical first until the practical is at the exposure you want it.
Second, light your subject and the rest of the scene to proper exposure.
A common problem that occurs is the practical is SO BRIGHT that to properly expose it makes the rest of the shot TOO DARK. And you don’t have enough external lights to bring everything back to normal. In that case you need to lower the intensity of the practical. By either dimming the light or using diffusion around the lamp shade. Or by switching the practical altogether.
That way there is a closer middle ground that you can find.
hello, can you please tell me exactly the method you used to correct the exposure? namely which ones you used from the color page. thank you
Late reply! But here we go. All I did was “re-grade” the new shot to look normal.
When I changed exposure and made the shot brighter I am now starting with a brighter image. Then I used the same grade which would be brighter overall. To “correct the exposure” I brought down the lift, gamma and gain to appropriate levels until the new image matched the same exposure to the one before even though it started brighter in the raw footage.
thanks for the video, great test/info
I’m in the minority here…I find your co trip image the best. More flattering skin tones to my eye and just a better look. The overexposed image is totally usable but I find her skin turned too white, almost like she had a little extra concealer on or something. In the control shot, again, to my eye, her skin had a nice golden glow. 🤷🏻♂️
Hey Jason! Thanks for your reply. Not everyone should like the same things and I'm glad we have some diversity in the comments. I probably could have added some red in the mids to counteract the "concealer" look for the grade. If that's your main critique maybe that will change your mind :) Taking a quick look back one thing I would've changed is to add some neg fill during the overexposed shots so there was still a fall off on the fill side.
Great test video! What does 1.5 stops overexposed look like in false color or waveform? Not sure how to measure this when behind the camera. I have the atomos ninja v.
Good question. I know that false color has a color key. So you can turn your exposed middle grey to the next color representing the next stop. For waveform I’m not sure but now Im curious to test it out. I also wonder if the dynamic range in the camera effects the waveform representation. The more dynamic range the smaller the adjustment on waveform, possibly.
It makes one wonder if the higher exposure looks better (overall) because the background goes darker, helping add separation to the subject.
Feels like you should have made one more shot with the +2 lighting and the camera properly exposed to the subject so that we could compare the adjusted “in post” frame to the as shot “in camera” exposure.
Nevertheless thank you for the video!
Great point! That could be playing subconsciously. A set light is needed to balance the background.
Nice!! Make one in an uncontrolled environment!
Thanks for the vid! Beginner question here. So for your test, you exposed for middle grey at the very start, and then never changed that setting the entire time, correct? So if I am shooting outdoors with the sun as a keylight, I would expose for middle grey at 400 iso, then ETTR the iso around 2 stops up or as high as possible without clipping?
Hello! The concept of ETTR I believe is exposing higher while keeping your ISO at its base ISO. So bumping your ISO two stops isn't the solution here because you aren't introducing more light for you sensor, you are just making the camera sensor more sensitive. What I did it this: I exposed for "middle grey" but not by using a grey card. I matched the light output in foot candles to the F stop on my camera. That's a fancy way of saying I used a light meter to find "perfect exposure". I could've used a grey card but I didn't but will add that to the next test. Then the only thing I changed to introduce more light into the scene is that I brought up the intensity of my lights. I did not touch my camera settings. It stayed the same. In your case shooting outside and using only natural light, the only way to introduce more light is to either bounce/reflect light or open up your f-stop. So if the sun is shining bright at an ISO 400 F5.6. Then overexposing by one stop would look like an ISO 400 F4. Also, my results came from shooting Blackmagic raw. You can achieve similar results shooting pro res as well.
@@filmmakersblog Thanks!
I agree the 1.5stops overexposed looks great....I'm using an Aperture 300d mk2...it goes up in percentages ....how do I wofk out which amount of Fstop I'm increasing by?
Great video cheers .
The percentages are not a good way to measure brightness. In order to really know you will have to use a light meter. Some camera's have a spot meter built in that can get you in the ball park. But I recommend using a light meter.
More in-depth video about this please 👏🏻👏🏻👏🏻👏🏻👏🏻
I am planning on playing with some more overexposure tests as well as an underexposure test. I'll let you know when they come out!
@@filmmakersblog Hey buddy, thanks for getting back. I have a couple of questions:
1. How are you matching the F stop on the camera to the K/B light? Are you using a light meter or how do you achieve that, how do you know when they are matching each other? It would be great if you could do a video about it as it is not very clear to me and I guess it would be also helpful to other people like me that are just starting out.
2. When you you fix an overexposed image than saying ‘we bring it down’ do you mean fixing it by using the primary wheels, the exposure or ISO tools inside the Camera Raw section in post or how is that achieved?
3. I just recently bought a Pocket 6K and it seems to me that whatever I do (either by using the auto-exposure button on the camera or just watching the camera histogram) the histogram is way lower to the left than it should be for the image to look good. In fact, if I try to expose the camera to level the exposure to centre of the histogram the image is way overexposed. Is this a camera issue or how does it work on the 6K?
I’m sure It would be extremely helpful if you could create a video showing:
- How you are matching the F stop on the camera to the K/B lights
- How you are increasing the exposure of the light by 1 stop etc?
- How you are fixing overexposed clips in post?
- What tools you are using to achieve that (eg. histogram, false colour, waveform etc.)
By the way, I do agree on the fact that an overexposed image looks a bit cleaner than a control one, especially in the mids and shadows area of the face. And yes, 1.5 stops look the cleanest of all.
Great stuff 👍
What an amazing reply. Thanks for putting in the effort to inquire. For a long form explanation I will 100% make a video. Stay tuned next Friday. In short, yes I am using a light meter to measure the light in f-stops. Yes I am using the primary wheels to grade and some other davinci resolve secondaries. Most of the other questions need a deeper explanation than I can give in this comment so stay tuned for the video!
@@filmmakersblog That's wonderful!
Very interesting. So now when you expose with false color you go for more pink/reddish instead of the green for middle grey or how do you expose?
Since you can set your middle grey to any value if you customize it I will talk in terms of waveform numbers instead of colors. Our control landed at 60. One stop over at 70 and 1.5 stops over at around 75. In post, I continued to push the image to about 95 to get the high key look I have in the video.
@@filmmakersblog Ah I see, will look into waveform again. Been using the internal false color for a long time now. Afaik you cant change the colors? This is the first time I hear about the overexposuse. Sounds exciting. I always notice how you can get back all the overexposed sky in any shot with raw, it's great!
The colors should match up with levels in the waveform. If you are using false color that's internal with your camera then you probably can't change the colors. I've been messing around with a SmallHD monitor I just purchased and in there I can program any color to be a certain intensity of brightness.
Great & Insightful Video
Thanks Kevin!
Love for flat pictures...
is she watching tennis ?
that pose is ridiculous, lol
I had her look back and forth so you can how the light falls when a character moves. But putting up a match would've been easier then calling it out every couple minutes.haha