Abstract: To prevent a transformer such as a trigger transformer from becoming unable to perform transformation as designed due to short circuits caused by leakage of an insulating wax or the like even when the temperature of the transformer becomes high, a sealed chamber is formed in an outer bobbin which accommodates a secondary winding by a sealing member and the sealed chamber is filled with an insulating wax.

Abstract: In a strobe zoom device of an electrically driven feed screw type, to reduce the sound pressure level of zoom operation sound caused by an electrically driven feed screw and to allow strobe imaging to be performed quietly, the electrically driven feed screw for strobe zoom includes: a feed screw rod (30) having a central axis and mounted to a casing (10) so as to be rotatable about the central axis thereof and extend in the fore and aft direction, the feed screw rod including an outer circumferential surface having a screw groove (32) formed thereon; and a wire member (34) attached to a movable body (planar lens plate (12) or a light source box (20)) and including a part wrapped around at least a part of the screw groove (32) so as to be in threaded engagement with the same.