Attach a wide-angle lens to your camera. These lenses expand depth, making it much easier to take forced-perspective pictures.
Locate the large object you want to appear small. For example, you may want to take a photograph of a girl at the Eiffel tower in which the Eiffel tower appears small in comparison to the girl.
Look through the viewfinder of the camera to determine how large or small the object appears. If the object appears too small, move towards it. If it appears to large, move away from it. For extra help determining the comparative size of the object, place the other object in the frame. For example, if you want a girl to appear large in comparison to the Eiffel tower, ask the girl to step in front of the camera.
Attach your camera to a tripod.
Position the small object in front of the camera. This object or person should be close to the camera. In most cases, the person or object will stand several feet in front of the camera.
Look through the viewfinder to check the perspective. The large object should appear small while the small object appears large.
Hold a light meter in front of the small object or person. The light meter should face away from the subject. Take the reading to determine the appropriate f-stop and shutter speed. Adjust the f-stop and shutter speed of your camera by moving the dials or knobs.
Slide the focus knob manually to adjust focus.
Press the shutter-release button to take the photograph.