higher-end tlrs may have a pop-up magnifying glass to assist the user in focusing the camera. in addition, many have a "sports finder" consisting of a square hole punched in the back of the pop-up hood, and a knock-out in the front. photographers can sight through these instead of using the matte screen. this is especially useful in tracking moving subjects such as animals or race cars, since the image on the matte screen is reversed left-to-right. it is nearly impossible to accurately judge composition with such an arrangement, however.