In an image taking apparatus, an arc tube and a reflector are moved forward when a zoom switch is operated to a WIDE-side and two reflection side plates are disposed such as to cover and hide Fresnel lenses located on both ends of a protector. Light emitted sideway from the arc tube is reflected from the reflection side plates, the light is introduced toward a central portion of the protector, and a radiation field suitable for a wide angle is formed. If the zoom switch is operated toward the TELE side, the reflection side plates are inclined such as to expose the Fresnel lenses on the both ends of the protector and the arc tube and the reflector are retreated at the same time, light emitted sideway from the arc tube is entirely guided to the Fresnel lenses, and a radiation field suitable for a TELE angle is formed.