What do Black Silks do

[andrew ward]

Another stupid question i should know.

 

Ive only seen a black silk used once, they were all raving about it but i was too busy to see the effect.

I understand youd use it as an overhead sun diffuser and the idea is to reduce the ambient bounce that white silk produces, but i dont get how black silk still diffuses and doesnt just act as a net. How can it be diffusing if its black?

 

Go ahead and hit me with the incredibly obvious answer which ive missed.

 

Someone should shoot a full on diffusion test. Itd be so nice to see a proper comparison of what they all do. Its too expensive to get enough variety to learn the difference. These days on small jobs offer up a "full diffusion" the dp wouldnt know if it was 216 or an equivalent, but itd be nice to know how it should be.

[Guest Stephen Murphy]

http://stephenmurphydop.blogspot.ie/2012/04/diffusion-bounce-rag-tests.html?m=1

 

Diffusion tests.....

[andrew ward]

Kinda...

[David Walden]

If it wasn't a net, it was diffusing the light just as a white silk would. But, it was also cutting the light down probably by several stops as well, creating a less harsh source and therefore more ambient light at a lower f-stop. So in general, the darker the silk, the more ambient lighting you'll get (talking specifically about using the silk to diffuse direct sunlight). Fyi, the texture or consistency of the silk is what *diffuses* the light, not the silk color. The color of the silk will either shift the temperature, or if using gray/black silks will cut down on the light intensity.

 

-d

www.davidwalden.com

[andrew ward]

Im with you apart from the bit about the texture of the silk being what diffuses.

 

I cant wrap my head around black diffusing. I understand white.

 

How is it different to like a lavender net then?

 

Isnt it like saying you can have a black bounce board?

[Guillaume Cottin]

Yes it is, and btw, you can have a black bounce board! You can even bounce light onto a black flag if you like. Of course it's not power-efficient but it's still a tool in your toolbox.

If I remember the AC article well enough, I think Roger Deakins did it when he shot the manor sequences in Skyfall. He would swap white rags to black flags so as to quickly switch from day interior to night interior.

 

It's the material that diffuses: if you do a black flag bounce, you will loose 3 1/2 stops but the light will be exactly as soft as with a white surface.

[andrew ward]

I dont get it.

If you put an 18k through a black floppy how does it diffuse it? What light gets through would be almost as directional as before wouldnt it?

Theres no white area to pickup light and transmit and make it softer.

The fact that the light hit something doesnt make it more diffuse, it either goes through it or it gets stopped.

Ill have to buy a black silk and try it.

[Guillaume Cottin]

Light can be absorbed, pass through or... bounce. There is some bounce even on a black surface like a flag or black poly.

 

Think of the black silk as a white silk + a scrim. But the black silk won't "glow" or bounce back like a white silk, and will do less spill. As a consequence there will be more directionnality and more specularity. You know when use use a white frame, the frame becomes the source ; well it's not completely the case with a black silk.

 

In a day exterior, the sun is such a strong source that you don't care about power efficiency. Using a large frame of black silk to block most direct sunlight while keeping some diffused directionnality looks good.

 

Having said that it's a tool that's rarely used.