Image pickup apparatus wherein plural elements simultaneously pick up the image and the state of the incident

An image pickup device comprising:

• a plurality of image pickup elements for generating an object image signal on the basis of a signal output from at least one of said plurality of image pickup elements, and for generating an incident light state signal on the basis of a signal from another image pickup element;
• and
• a readout cycle of said at least one image pickup element being different from a readout cycle of said another image pickup element while said object image is supplied to a viewfinder,
• wherein said device has a first mode for generating the object image signal using a part of said plurality of image pickup elements and for generating the incident light state signal on the basis of a signal from the rest of said plurality of image pickup elements, and a second mode for generating the object image signal using all of said plurality of image pickup elements.