Relaying Light: Using Diffusion to “Fix” Natural Light by Art Adams

[Chris Hurd]

We have a new article published on DVi by Art Adams. The link is:

Relaying Light: Using Diffusion to “Fix” Natural Light at DV Info Net

"My lighting budget had to cover the needs of all six spots over five days, so I had to build an equipment package that worked for everything. This car was the only location that would normally have required some big lights to balance a dark car interior with a day-lit exterior and keep the quality and direction of light consistent over time, but we didn’t have the money for a generator and a couple of large HMIs. Fortunately I had two tricks up my sleeve: an Arri Alexa and a 12′x12′ frame of full grid cloth."

[Chris Medico]

Excellent info in that one.

[Chris Hurd]

He's good. He's very good.

[Les Wilson]

Couldn't agree more. Love my pair of Zylight Z90s.

[Charles Papert]

Good for many people to think about diffusion as a way of changing the direction of light.

I will say that watching the spot before reading the article, I could guess that a double net was in use on the background, the milkiness was an immediate giveaway. I used that technique many times over the years with video but stopped doing that once the highlight rolloff in cameras improved to where blowouts became more forgiveable. Never cared for the look of the backgrounds with a net in place, it was just a necessary evil. Discovering at the end that Art chose to record in 709 was a definite puzzler--if he had shot Log-C he would have been able to contain the highlights at least as well as the net did and with a better look.

[Craig Chartier]

No money for HMI, then no money for LOG Charles,, '-)

[Charles Papert]

hmmm? Log is free if you are using an Alexa, as was the case here...

One can only plan for so many contingencies with a given budget. In this case, I'm sure Art had a backup plan of sorts but had it been a lightly overcast day, it would have been tough to balance inside the car once the ability to bounce or diffuse the sun went away. Of course the light level overall drops and smaller HMI, such as that which can be powered from a putt-putt, can be put into use.

I recently produced a project and the DP proposed that we shoot the daytime interiors using shiny boards outside to push light through the windows, i.e. no HMI. I was too concerned about contingencies (such as overcast weather) and sprang for the modest HMI package out of pocket. Sure enough, actor scheduling changed on the day and we ended up shooting a major day scene with our biggest name actor at night, using every unit we had. So yeah, I get particularly nervous when relying on natural daylight as a lighting source because changes in weather or scheduling can put you into a dangerous spot.

Pulling out "parlor tricks" is a great asset for a DP. I constantly baffle my grip and electric guys with some of my notions when we don't have the "right" tool for the job, or things change on the day. We brought in a strobe unit a few weeks ago to simulate gunfire playing on the shooter's face, and when the strobe overheated after rapid bursts we resorted to my tried-and-true cheapie way to pull this off (described in this thread.

[Craig Chartier]

I was making the silly point that they should have sprang for HMI's in order to help make the shoot go smoother. And since they didn't have that in the budget, why would they have any extra money for someone in post to work with LOG,, when 709 is "good enough"

Yes we all have had to pull rabbits out of our hat in order to make it work, usually at the cost of extra man hours, just to save a few bucks. That frame and net didn't move itself from one side of the car to the other.

Your experience told you to find the funds for HMI's vs the shinny boards. Those lessons are earned over time and having bad experiences. If you were the DP and not the Producer would you still have donated the cash for the HMIs or would you have taken your chances with the shinny boards after having been told by the producer "no money for HMIs"

[Charles Papert]

Again, it was Art's shoot, it clearly went well and he got a good result, so I don't want to disparage his approach and I certainly acknowledge that the core concept of the article, redirecting sunlight via diffusion, may be very helpful for those who hadn't previously grasped this concept. It's not for any of us to say that they "should" have had HMI's on this shoot. To speak to the idea of "would I take the chance" on this or the shoot that I described, I would have (and in the past have) made my best argument to production describing the worst-case scenario of overcast or intermittent sun and what the risk would be to the look. Essentially, it's covering your ass and it doesn't always work, but it's the only thing you can do.

As far as log vs the cost of large HMI: I would find it hard to believe that in this day and age there isn't budget for a project that hires actors for some form of color correction. You don't have to go to a legit post house any more to do a reasonably good color grade. I've colored a number of projects I've been involved in and while I'm not going to call myself a colorist in any form, I can certainly lob a curve onto a log project and massage things to match. Bringing in 6K/12K/18's and a 200 amp genny is a much more formidable line item no matter how you slice it. In this instance, I'd probably gun for an M18 to push through the same diffusion if needed plus a Joker 800 for fill, which would be sustainable on a 6500 putt-putt for a much more reasonable cost than a full-size HMI/genny/cable package.

[John Nantz]

I'm really trying to understand what is needed here and, before I go any further, please don't turn me into a dart board.

In post #1 it was state [excerpt]: "... required some big lights to balance a dark car interior with a day-lit exterior and keep the quality and direction of light consistent over time,...."

Hopefully this is not taken too much out of context and changing the meaning.

But, if one wants to lighten up the interior of the car (granted, to match the daylight outside), would it be possible to put some small lights on the inside of the car and to get the light more even, drape some white sheets or foil "space blankets" around inside, say over the back seat, tape some to the coach roof overhead with blue 3M tape (less sticky than duct tape), and basically add light to the inside of the vehicle?

For color temperature, maybe gell the lights? I'm thinking of smaller but quality LED vice the cheap stuff with green spikes.

The reason for this suggestion is I've been playing around with my recent Comer LBPS1800 and it can put out quite a few lumens (adjustable). I've used it as a fill on two occasions with good results temperature-wise. Maybe this is a deal breaker because being a professional project the acceptable tolerance for temperature compatibility may be to a higher standard than what I'd accept.

The example picture had a "cool" color that would be more white LED compatible but if a warmer tone was needed then in the case of the Comer light some of that is possible. (and there is gel)

Supports for small lights aren't a problem as there are some really small tripod camera supports, like with six-inch legs, available.

Am I missing something here?

Anyone dare to comment on this?

(Disclaimer: I'm a hobbyest with thick skin so I think I can take it.)

[Charles Papert]

Hi John:

You shouldn't hesitate to ask questions, that's what the board is for!

Duplicating the look of daylight requires one to conform to the directionality and quality of existing light. Once you start introducing it from places that it doesn't really come from (the ceiling of the car etc), you risk it looking "lit" or just plain strange.

Daylight is primarily composed of sun, which is a single, very bright directional point source that sustains intensity over a great distance (so, seeing the light fall off across the set is a giveaway). Then there is the ambient light of the sky which consists of scattered rays like a huge soft light and is bluer in color than the sun. Finally there is the interaction of both of these with surfaces on earth which will bounce and redistribute the light in various ways.

In all instances, a small unit like most LED's will read "false" as it doesn't duplicate either sun or sky in either intensity or quality. This is why we use large units like HMI's as they have enough punch to appear as intense as the sun, or can be bounced or pushed through diffusion to simulate ambient light.

Given the interior of a vehicle is lit during the day by ambient that wraps all around the car and illuminates equally through each window, plus the sun if applicable which punches in at a given height and direction, you can quickly see that it makes "sense" for the source to be placed outside the car, as that is where the natural light originates. If sun is present, you can get away with a certain amount of bounceback that could occur, such as a hot backlight from the sun through a window and then a soft bounce coming from the opposite side, as if the sun is reflecting off a surface and hitting the actors. I will occasionally place a piece of white card on a seat or taped to the dash when the sun (or my HMI source representing the sun) is in the right direction to bounce this way; if done properly and just the right amount, this can be believable. In some instances this bounce can be replaced by a lighting unit, but it should be a soft source and just the right color.

This sort of thing is best shown rather than described...I'll try to dig up some other examples.

[Craig Chartier]

Hi John

We are all here to understand, and thats what makes this forum great. Your post is actually getting back on track.

Its really about trying to equalize or perhaps being able to control most all the light, internal and external as well as control of shadows. Sunlight hitting the trees and buildings and the street. is what it is. If you want to see those details, or at least not blow them into digital nothingness, you will need to try and match the exposure levels. Yes you could try outfitting the inside of the car with lots of small lights, but you always add a shadow for each light source you turn on. And you start to limit your ability to pick placements for the camera.

You need a big source in order to compensate, and for this shot HMIs would have given that extra punch without limiting your ability to control shadow detail. You still would have used nets, flags, ND gel, Diffs, etc,, its all up to what your a custom too working with.

What Art did was work with the tools he had at hand, and it turned out great.

Hope that starts to answer your question.

[John Nantz]

Originally Posted by Charles Papert

Given the interior of a vehicle is lit during the day by ambient that wraps all around the car and illuminates equally through each window, plus the sun if applicable which punches in at a given height and direction, you can quickly see that it makes "sense" for the source to be placed outside the car, as that is where the natural light originates. If sun is present, you can get away with a certain amount of bounceback that could occur, such as a hot backlight from the sun through a window and then a soft bounce coming from the opposite side, as if the sun is reflecting off a surface and hitting the actors. I will occasionally place a piece of white card on a seat or taped to the dash when the sun (or my HMI source representing the sun) is in the right direction to bounce this way; if done properly and just the right amount, this can be believable. In some instances this bounce can be replaced by a lighting unit, but it should be a soft source and just the right color.

The part about the ambient light wrap around the vehicle I can understand, especially locally where our sky is typically overcast or cloudy-bright as Kodak would call it. Once in a while we get severe blue skys but not often enough. In one way, overcast may be easier because there would be fewer bright hot spots, like sunlight on chrome or a painted metal surface.

The picture of the couple in the car with the dark overhead, door panel on the passenger side, and the door post (between the front and back seat), and the dark hair of the passenger who seems to have fairly light colored hair, was what I was looking at. I realize that the original picture may have been lighter in the shadows as some hosting sites can change the color or brightness of the picture. Anyway, I think I was fixated on the this part of the picture and not really looking at the big picture.

Your idea of taping a piece of paper on the dash to provide a tad bit of light was a good one. Maybe if the gals hair had a touch of light to it, not a lot but something to take the edge off of the darkness, maybe I'd like it better. On the other hand, this isn't a Rembrant picture and time is money.

Yesterday I just sold a couple Rycote Softies and now I've got some money burning a hole in my pocket. Two things I'm looking at are these Vortex Media Warm Cards WarmCards - White Balance Reference System and their "How To Do Interview Lighting video" although I really don't do interviews.

Currently I've got one Porta-Brace white balance card that I picked up with some gear and that's it. And, I haven't really used it much yet. Seems like it's never around when you need it, or, it's a time thing and there's no time. But I'm determined and not giving up. The forest or woods problem with the green tint I can see happening in the future and I'm thinking these cards may help. I'm also wondering how they might have been used in the shot shown in Post #1, if at all.

[John Nantz]

Originally Posted by Craig Chartier

If you want to see those details, or at least not blow them into digital nothingness, you will need to try and match the exposure levels. Yes you could try outfitting the inside of the car with lots of small lights, but you always add a shadow for each light source you turn on. And you start to limit your ability to pick placements for the camera.

I can see that now. There is also a point of diminishing returns on how much effort one can put into lighting a shoot.

For the past half-year or more the videographers around here, me included, have been sort of hibernating, I think. Between the rain, cold, and generally unpleasant outdoor climate, it just isn't conducive to doing anything outside. Now that the weather has changed (a high of 61.8 and overcast, 70% chance of rain today) there sees to be an urge to get out there and start doing it. I've got that itch to get some outdoor footage (Gigabytes?).

I've got a Westcott 6-in-1 and some umbrellas that haven't got as much use as they should have but they haven't been forgotten. I clearly need to do more lighting work.

[Charles Papert]

In this day and age where sophisticated color correction is available to all (I still can't wrap my head around the free version of Davinci Resolve--talk about a gift), the subtlety of in-camera color correction is not as much a necessity as it once was, unless one is handing off footage and dubious that it will get properly colored down the road. I used to have a little book of gel scraps of different colors that I held in front of the lens while white-balancing to correct color temperature and green/magenta shift, providing the same results as warm cards etc.

With the Alexa (which was used to shot those spots), you can dial in color temperature and green/magenta values directly as well as perform auto white balance so it's pretty easy to achieve what you want in-camera.

Next Thursday I'm shooting a scene of two people sitting in a car having a conversation, and perhaps I will take stills of how I went about it (it almost certainly won't be using Art's methods but that's because I do have multiple HMI's, genny etc at my disposal)!