Getting the target in the right place and setup up appropriately is important. To save any concern over whether your test results are valid, FoCal had a Target Setup utility which shows you a LiveView display of where your camera is aimed.
Guides on screen shows you if any adjustment is needed – from the size of the target image, distance from the camera, any rotation of the target, or even whether the camera and target are parallel! When everything is set up right, a big green tick shows you that you can continue with any tests:
For further information about this and other tests, the latest FoCal Manuals are available from the Document Downloads page.