Electronic still camera with capability to perform optimal focus detection according to selected mode

A method of controlling an electronic camera of a single-lens reflex type, capable of selecting between a first operation mode that enables observing a subject image with an optical finder, and a second operation mode that enables observing the subject image captured by an imaging element and displayed on a monitor, the method comprising:

• when the first operation mode is selected,
• setting a quick return mirror in an optical path of an imaging lens;
• and
• measuring luminance of a subject via the optical finder, and determining a first exposure condition, and
• when a release switch operation is detected,
• setting the quick return mirror outside the optical path of the imaging lens;
• and
• controlling the imaging element to obtain first image data of the subject based on the first exposure condition, and
• storing the obtained first image data in a recording medium;
• and
• when the second operation mode is selected,
• setting the quick return mirror outside the optical path of the imaging lens;
• obtaining second image data of the subject using the imaging element, and displaying the obtained second image data on the monitor;
• and
• measuring luminance of the subject using the imaging element, and
• determining a second exposure condition, and
• when the release switch operation is detected,
• controlling the imaging element to obtain third image data of the subject based on the second exposure condition, and
• storing the obtained third image data in the recording medium.