Best practices for blowing out highlights on 4k sensor

I want to purposefully let things blow out, especially windows. However, I'd like them to rolloff like film negative. I've not really seen anyone talking about trying to achieve this, as most people seem to want to do highlight recovery on overexposed footage.

I assume I should do a double-hit with careful exposure and careful grading in the highlight areas.
I'm not necessarily interested in highlight recovery, I'm interesting in letting things go. This will be controlled, on a set, and I plan to blow out windows with diffusion blasted with maxi brutes.

Does anyone have experience purposely blowing things out on the 4k sensors?
Best practices?
Best workflow?

My initial thought is to push things as far as they will go on set, and let things blowout just to 100% on the zebra, I'll try to watch my scope and clip as little as possible, but I'm not sure how best to solve the "no clip but still blowout" issue. Letting things clip past 95% zebra on my Pocket has always produced excellent results. As I have the most experience with this technique on the Alexa Classic, I thought I would ask here if anyone also utilizes blown highlights.

Well, to have a nice roll-off into blown highlights, you still need to keep the highlights below clipping, or, at least the areas of the image where you want the smooth roll-off to occur needs to be below clipping. Once it's clipped then it's clipped. Doing a "highlight recovery" is simply bringing over-exposed, yet, not yet clipped highlights back down to where they no longer look blown-out. You still shoot it the same way if you want it to be blown out, you just don't bring the highlights back down in post. You allow them to be blown out.

Blown out doesn't need to mean "clipped." In fact, I would want to make it a point on a controlled set to never let anything be clipped, in the highlights or the shadows. Because, you never know.

I'd much prefer to have the information there and then choose to crush the blacks or the whites if I wanted. But, to have an image that simply doesn't have the information because the extremes are clipped? That can be avoided on a controlled set.

Expose for the highlights (and you can control them, so that means stopping them up or down any way you want to make them appear blown out, light up the shadow areas by increasing the exposure of the shadow areas and stopping them up or down depending on how dark they should appear, then light for the midtones/skintones/talent/subject/etc for mood/taste/etc...all the while not allowing any of these areas to be so under/over-exposed that you clip and lose detail.

Reality work is different. There you can't control the situation so you simply expose for the most important subject. That means windows get overexposed and clipped and shadows get very noisy but at least the subject is deliberately exposed for. On a controlled set, you can [obviously] control all that. The rest is artistic expression.

I'm always surprised how far you can recover something that appears blown. I've thought it surely would be clipped, but the data is usually all there.

One of the joys of grading is developing what you have the way you want it. As Jason says, "any way you want."

I expose with 90% zebras but don't worry if zebras begin to show because the red false colour doesn't mean I have clipped but is a warning I may clip.


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Using lights through diffusion might work but why not just control exposure in the room using flags and negative fill? If you keep your key and fill low the outside is going to blow out anyways unless you're on a set trying to fake it or it's night. Really firing a bunch of light through diffusion is just going to create more ambient light in the room (necessitating a higher stop, and mostly chasing your tail) and it's soft so it's going to be harder to control. Generator or a roll of duvetyne it's your choice. If you want a smoother highlight rolloff, filters like Ultracons, Digicons, and some of the lighter strength mist filters can help here.

Good Luck

Using lights through diffusion might work but why not just control exposure in the room using flags and negative fill? If you keep your key and fill low the outside is going to blow out anyways unless you're on a set trying to fake it or it's night. Really firing a bunch of light through diffusion is just going to create more ambient light in the room (necessitating a higher stop, and mostly chasing your tail) and it's soft so it's going to be harder to control. Generator or a roll of duvetyne it's your choice. If you want a smoother highlight rolloff, filters like Ultracons, Digicons, and some of the lighter strength mist filters can help here.

Good Luck

I probably was not at all clear in the original post so let me clear up a few things that may make more sense.

I am going to shoot towards the window and don't want to see the outside. Our working stop is T8, and I are working ISO is 100 shooting at 400 on the camera with a 45 degree shutter angle. I want the window to go, I need itto blowout and don't really care to see the outside. The use of a softening filter may work well in this situation, but we are actually trying to push sharpness as much as possible in camera.

I guess really the only option is to push the window as far as it will go without clipping and then fill in the subject however many stops under for normal exposure.

Test test test everything tested. report back after the tests, thanks for the suggestions.


Edit: p.s. one time I pointed 17000 Watts directly into a wide open lens on the pocket and I was very surprised at the amount of detail that was still present I could not make it blowout like I wanted to even wide open at ISO 800.

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Try putting a white scrim on the outside of the window, and add more light to it as required, or if enough daylight, that should block out the window and balance the rest of the scene.

You're shooting interiors at f8, 100 ISO, 45 degree shutter? Good Luck, try not to burn the place down.

You're shooting interiors at f8, 100 ISO, 45 degree shutter? Good Luck, try not to burn the place down.

Camera is set to 400, but we're down two stops with the shutter setting. I may open that up a bit if I don't have enough light, but I brought the big genny...

If you're intentionally trying to blow out windows then just put a white board or cover them in 1/4 artificial silk or similar and blast them with light. If you want to control the gradation and have them be blown but not clipped, then see my previous post.

Can't imagine anyone intending to clip something as large as a window as that's going to be hard on the eyes. Unless the blown area is used for compositing other footage in post.

Edit:
..: Unless the clipped area is used for compositing.

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Rick, Rick, Rick...

Am I not supposed to link to other forums from here? I'm going to err on the side of caution and merely instruct you to put this in your next Google search "90 Minutes in Heaven David Mullen" and look for the cinematography dot com link.

Therein, David Mullen, ASC, describes shooting with "blown out" windows that were made to blow out using diffusion material attached to the doors/windows or bounce material just outside, hit with a large source like an 18k HMI. Purposefully blowing out the unattractive or inappropriately period-specific outdoors.

The good stuff starts on page 2.

But, that's just blowing out the window. CLIPPING a window is still not something I'd want to do. You need those subtle gradations or it looks like crap digital video. It's a lot easier today to get smooth gradients out of regular video cameras, let alone with the 15 stop and above cinema cameras at our disposal. And, of course, it's also just as easy to frak up a shot because fella didn't know how to light.

Jason, I was referring to clipping. I often have used 'blown' intentionally but don't want anything besides the sun and specular highlights to clip.

Corrected my confusing post that used the terms interchangeably as that wasn't my intention.

Thanks for the reference to David Mullen. He's such a generous DOP and always gold as a mentor. Reminds me of someone else we know, John what's-his-name?


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...something browlee? Crowley? Nice guy. The kinda guy you wanna buy a beer for.

Speaking of clipping: I'm starting to hear my fingernails hitting the keyboard.

[BLACK SCISSORS]️

You not be able to see the emoji 'black scissors.'

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I use a Tiffen Ultra Contrast 3 on my Mini 4K sometimes.
It does help with getting a slightly less digital looking highlight roll-off.