The most commonly-seen way photographers de-emphasize backgrounds is with aperture. By shooting at open apertures we reduce the depth of focus. Nothing wrong with that! It's an effective strategy forcing viewers' eyes where you want them-- on your model.

It's not the only way, however, the effect can be achieved.

Often enough, I've found myself in shooting environments where I can use a background element to de-emphasize whatever is behind the model. A sliding screen door, for instance, does a nice job of diffusing and de-emphasizing the background. It works even better when you can take advantage of sunlight behind the model.

When sunlight is behind the model, yet the model is inside and you're using a screen door as a background element, the screen will not only de-emphasize the background but will act as a scrim, knocking-down the natural back light.

Many videographers use screens in the background when shooting "talking-head" interviews. Video cameras, with their shorter focal length lenses, aren't always agreeable to reducing depth of focus optically when shooting at open apertures but with wider framing, that is, with the lens zoomed out. A screen behind the "talking head" can create an effect which helps videographers de-emphasizing the BG and keeping viewers' eyes on the person who is speaking.

Some companies make and sell collapsible screens, just like they do with collapsible seamless backgrounds, often in green or blue for making composite shots in post-production. ("Chroma Green" or "Chroma Blue" screen effects.) Often, these collapsible screens are on the large-ish side, in the 5' x 6' or 7' diameter ranges, so they can cover a fair amount of background space. Certainly, enough space for a nicely composed medium close-up that works well for interviews and/or on-screen announcers or narrators.

Photographers can also employ these same collapsible screens for shooting portraits and headshots. Or, a simple trip to Home Depot, Lowes, or any hardware store will yield inexpensive materials to make your own, DIY, background screen. All you'd need is some lengths of PVC and four right-angle corners, plus some of the same screen material you'd use to re-screen a door. Your PVC frame could easily be assembled when setting up for shoots. The screen material could be affixed to your DIY frame with A-clamps and the whole thing placed in the BG attached to a couple of light stands or some other way to prop it upright.

With the screen placed a nice distance behind your subject, focus on the screen is reduced even at smaller apertures. This means less chance the texture of the screen will be revealed. Instead, the screen remains, basically, invisible while causing the background (the background behind the screen) to be de-emphasized. It also allows the photographer to shoot at smaller apertures where critical focus is more easily maintained.

The pretty girl at the top is Nikki. I shot Nikki in a location house in front of a sliding screen door allowing me to still see through to the exterior flora, but that exterior is de-emphasized by the screen. Sunlight is providing the back-lit highlights on her hair and shoulders and a 5' Photoflex Octodome is modifying my monolight main light. It almost seems like an exterior shot but it's not. As you can plainly see, this technique really helps "pop" the model.