Scrims are devices similar to diffusers and almost serve the same purpose. When we say almost we mean it, both of them reduce the amount of light passing through, the intensity is reduced in both cases. What distinguishes one from other is the effect it has on the quality of light. While diffusers alter the quality of light by making it softer, scrims only reduce the intensity of light and do not alter its quality. The other difference is that diffusers alter the size of the light source, when used between the light source and the subject, the diffuser becomes the new light source and it’s the diffuser’s size that is the size of the new light source. But this does not happen in case of a scrim.
|Scrims used in photography to control light|
Scrims usually comprise of a frame with mesh material stretched across it. The scrim screen should be ideally made up of black material, if not it should be some very dark color. Else it will have the effect of diffusing the light.
Scrims are also referred to as nets; they are like Neutral Density filters for your lights.
Imagine you are shooting fashion outdoors. The main reason why photographers choose to shoot fashion outdoors in broad daylight is to utilize the harsh nature of direct sunlight and the result it has on images. If you would like to use a wider aperture (for this you need to cut down a couple of stops of light); you have two options.
First option is to use a Diffuser
In this case what happens is that the diffuser now becomes the new light source and it diffuses the light to a soft light with soft shadows and you get pictures with less contrast and less definition of shadows.
Second option is to use a Scrim
In the scenario given above using a scrim you could easily achieve your aim by reducing the intensity of light while retaining all its other properties. The size of the mesh controls the amount of light it lets through, so you could control the light by using different mesh sizes. You could also experiment by stacking more than one layer of nets.
A third option that we let out on purpose because it falls out of the scope of this article is the use of a Neutral Density Filter. However there is one major difference between using a Scrim and a Neutral Density filter. If a ND filter is used, it reduces light evenly across the scene. And when a scrim is used, it only reduces light on the subject with the background remaining at the original levels, thus giving the subject an appearance of popping out from the background.
In the next article we will discuss about Light Modifiers - Diffuser