The Earth-orbiting Solar Dynamics Observatory provides a live image feed of the sun at all times. The Solar Capture app basically displays these images from NASA and provides a simple interface for browsing them and saving to disk. This is especially handy for events like Venus transits or solar eclipses.
Just open the app, select an empty folder to store images, and it will start updating automatically. There is no need to set the update interval smaller than 15 minutes, as the images on the NASA server aren't updated more frequently.