Scrims vs nets vs ND?
 

Clueless question, what is the difference between these modifiers? When would you use which?

I found some interesting information here -- Net & Scrims CML-Cinematography Mailing List -- but am still very curious to hear anyone else's opinions/experiences.

Re: Scrims vs nets vs ND?
 

They all reduce light, but the real differences boil down to pretty sensible things. A metal scrim can dim a 10k discharge fixture, using any of the others results in smoke or a sticky mess or worse. You can stick a sheet of ND on a window, and still see the flowers outside, but not with the others. The fabric style devices are white, so reduce and soften the light, changing it's quality, but if it is used on a hot source, it needs air space. So the choice depends on what you need to darken. They all have good and bad points.

Re: Scrims vs nets vs ND?
 

Adrian: three different, separate applications.

1. Scrims lessen the intensity of the light, but not so much the sharpness or shadows. If you are looking for a hard edge, but just not so bright, you can drop in a scrim. Or back off the light. Or use an electronic dimmer.

2. Nets/silks are diffusers. They turn a hard point source light into a bigger, softer light. They also tend to spew light all over the place, so flagging or controlling the light becomes more important. If you are looking for softer light sources, explore softboxes like the Chimera or others. When mated with a fabric grid on the front of the softbox, makes for a nice, compact soft key with little spill. It does drop the light fixture output a bit though.

3. NDs are designed to cut the amount of natural light streaming in through windows. Gelling windows with ND material is generally a royal pain, and requires a lot of set up time to do it right. Another way to reduce ambient light behind an interview subject is to stretch a black mesh behind them. This works really well outdoors. You can also do it indoors, but you need enough separation between the subject and the net, or a large sensor camera with a fairly wide open lens to blur out the mesh.

Re: Scrims vs nets vs ND?
 

You can also get ND filters for putting on lights.