1. A method for forming an image when testing an electronic device comprising a camera for forming an image on a detector, the method comprising placing a holographic element, comprising a holographic test image, and a camera under test of the electronic device at a predetermined test distance from one another in order to form the image from the holographic test image on the detector of the camera under test, whereby the image field of the camera under test includes an unfocused holographic element, the holographic test image of which is arranged to form a focused image on the detector of the camera operating as desired.