If you shoot with flashes, then a grid can be a super handy tool for putting your light exactly where you want it in the frame. If you’re a fan of DIY photo sites or The Strobist, then you know that making a grid can be achieved with some simple and extremely cheap materials. This video gives a quick, clean demonstration of how it works.
The process is pretty much as you’d expect: You cut some straws to a certain length, secure them together, then insert them into a frame made of black card stock and tape. The result is a grid that you can customize to meet your needs. The longer you make the straws, the more directional the light will be. So, if you want a very bright, tight spot of light, make it longer. If you’re just trying to keep the light off of your background, you can make it a little shorter.
From: ISO 1200