1. An image pickup system comprising: an image pickup device, and a connection device connectable to said image pickup device, said image pickup device including an image pickup unit which picks up a subject image, a display unit, a first character image generation unit which generates a first character image representing one or more characters, and a first control unit which allows said display unit to display said subject image, said first character image, or a combined image of said subject image with said first character image, when a connected state in which said image pickup device and said connection device are connected with each other is not established, said first control unit outputting said subject image and information representing said one or more characters to said connection device when said connected state is established, said connection device including a second character image generation unit which generates a second character image representing said one or more characters based on said information representing one or more characters received from said image pickup device when said connected state is established, and a second control unit which allows an external display device to display said subject image received from said image pickup device when said connected state is established, said second character image, or a combined image of said subject image with said second character image.