Diffused kino versus book light (hmi bounced off ultra bounce diffused through muslin

[omar robles]

Hello group:


So I am trying to achieve the stylized lighting of Roger Deakins and I read that he uses a lot of bounce light off bleached muslin. My question is could achieve a similar look diffusing a kino flo through bleached muslin material? To me it seems it would be easier to simply diffuse a kino and save the step of bouncing say an HMI to an ultra bounce and then through another layer of diffusion. Is the quality difference that great?


Thanks


O.R

 

[Nick Morrison]

I'm no DP (only a lowly director), however diffusing a relatively small Kino....vs bouncing an HMI off a huge bounce...and diffusing that... suggests that it would most likely be quite a different type of light: one smaller, punchier....the other much larger, softer.

At least...that's how I interpret it anyway!

 

[David Mullen ASC]

I hope Omar wasn't thinking about a single 4' 4-bank Kino replacing an HMI bounced into a large surface, but instead a spread of Kinos creating a wall of soft light of similar size to the bounced area, either then passing through a larger frame of muslin. I think the main difference then would be intensity, not softness.

 

[omar robles]

David

I was just talking aesthetically in theory they should look similar. Seeing as the objective of using a book light and diffusing it twice is to soften it in the end. And with a kino flo it seems to me your bypassing having to diffuse it twice.

 

[David Mullen ASC]

There is a lot of voodoo surrounding soft lighting techniques...

Think of it this way: the softness of a light is determined by its SIZE as a source (the diffusion frame or bounce surface is considered the light source in this case, not the unit lighting that frame of material) relative to the distance to the subject. THAT'S IT.

So if you light a 12' x 12' frame of diffusion material evenly from edge to edge with no variance in intensity throughout, or fill a 12' x12' bounce surface evenly in the same manner, it cannot get any softer as a source unless the subject moves closer to it.

That's all you need to know, it's the size of the soft source that determines its softness. What different different materials do and what doing a book light does is just create variations in how evenly you can fill that diffused area because it is very hard to perfectly fill a diffusion frame from edge to edge. But once you do it, the light cannot get any softer, so adding even more diffusion material isn't going to add more softness unless you are using the soft source to fill an even larger diffusion frame.

I recall a demo that Roger Deakins did at a union lighting seminar where he lit (with 1K's I think) a subject with a semi-circle of 4'x4' bounce cards and then re-lit with 4'x4 diffusion frames with the light passing through the frames. He basically got the same effect either way. His point was to not overthink this issue of bounce versus diffusion frames, a soft light is a soft light -- which technique you choose is partly just a practical issue, i.e. do you have more space behind the material for the light or in front? Also it is easier sometimes to set up flags in front of a diffusion frame rather than a bounce card because you don't have to work around the lighting unit.

So in regards to a Kinoflo, the size of the soft source is the size of the unit, with a 4' 4-bank Kinoflo, it is roughly a 2.5' x 4' soft source. So if you set up a white surface instead of a Kino but bounced a Source-4 Leko into it with the blades pushed in to create a rectangle of light that was 2.5' x 4', it would be similar in softness to the Kino, assuming no hot spot or kick in the surface of the bounce card.

So when asking if a Kino would be just as soft as an HMI bounce if either were passed through a diffusion frame, it depends on the size of the HMI bounce area. Odds are high that it probably would be a bigger area of light on the bounce surface that 2.5' x 4', right? So it would be softer than the 4' 4-bank Kino. But let's say that the bounce area is roughly a 5' diameter circle -- well, two 4' 4-bank Kinos, one over the other to create a wall of 8 tubes that is about 5' x 4' in size, well, that might be similar in softness to the HMI bounce area, at which point the difference will probably be more a matter of intensity depending on how bright the HMI was.

It also depends on how evenly you fill the diffusion frame you are aiming the Kinoflo through versus the HMI bounce. It is conceivable that a single 4' 4-bank Kino could fill a 12'x12' frame of diffusion evenly if backed far enough away, more evenly than an HMI bounce that was much closer to the 12'x12' diffusion frame, in which case the Kinoflo would create the softer effect. But by that logic, a hard 650w tweenie backed far enough away could evenly fill a 12'x12' frame of diffusion and create an equally soft light, assuming a fairly heavy diffusion material.

 

[David Mullen ASC]

FYI, Robert Richardson used a giant wall of Kinoflos behind diffusion to create a dim grey ambience on a heavily fogged soundstage to create the opening of "Snow Falling on Cedars" of a boat at night stuck in a fog bank, the softened Kinoflo light basically just glowing the smoke evenly to create a dim separation from the silhouetted foreground elements.

But as for why someone might bounce an HMI and then pass that bounce through a diffusion frame, it might be because he needs the intensity of a bright HMI, maybe he's bouncing a couple of 6K HMI PAR's into a 12'x12' frame and then passing that through a 20'x20' frame of muslin -- it would be hard to get a wall of Kinos to be as bright as some 6K's bounced into a white surface.

 

[David Mullen ASC]

When you start lighting a lot using different soft light techniques, you notice that some are softer than others but that's OK, the point isn't always to achieve maximum softness, there can be a lot of beauty in a barely softened hard light, for example. And some DP's like to use "imperfect" diffusing materials that allow some faint specular light to leak through the material, feeling that this creates a textured soft light that is more organic than a perfect soft source.

I think you also have to be practical regarding power consumption and heat generation, and the size of the set-up and the time it takes to set it up, etc.

And sometimes you just have to find quick and simple solutions. I remember being asked by the director to set-up the lighting for the videotaped auditions and being given just two Kinoflos and no grip support other than the stands for the Kinos. The direct Kinos were too hard so I turned one around and bounced it into the white wall next to it for a side key, and took the fill Kino and bounced it into the ceiling above the camera for a dim ambient top light.

 

[omar robles]

Thanks David

Very gracious to share your knowledge. I think i can speak for everyone in saying we are all grateful.

 

[sander kamp]

Thanks a lot David for taking the voodoo out of it!

Wouldn't the difference between a smaller soft light closer to the actor and a bigger farther away also be that a light source closer will fall off quicker then a light source farther away? So in the first case an actor can't move too much without getting variance in the light intensity but the light will also spill less on the background?

 

[ericyoung]

Thanks a lot David for taking the voodoo out of it!

Wouldn't the difference between a smaller soft light closer to the actor and a bigger farther away also be that a light source closer will fall off quicker then a light source farther away? So in the first case an actor can't move too much without getting variance in the light intensity but the light will also spill less on the background?

This is true, following the inverse square law, but often you just do the best you can with the space and the lighting kit you have, if you're in a small set/location or don't have the budget for larger higher wattage sources.

 

[David Mullen ASC]

Thanks a lot David for taking the voodoo out of it!

Wouldn't the difference between a smaller soft light closer to the actor and a bigger farther away also be that a light source closer will fall off quicker then a light source farther away? So in the first case an actor can't move too much without getting variance in the light intensity but the light will also spill less on the background?

Yes, sometimes you want a fast fall-off and sometimes you don't, but often it is better if you don't crowd the acting space too much with the lighting units, unless the actor doesn't have to move much, like when sitting at a table.