My D90's shutter release sometimes stops working while in manual mode\nwith an MF 100-300 zoom at f8 (internal focus, max f4 through range) in\nfull daylight. I can take a few shots, then the shutter release stops\nworking when pressed all the way down. Can get shots when camera points\nat the ground or sky (completely out of focus) or occasionally after\nzooming out. Can't tell for sure what makes it start working again,\nassume this is related to focus and the electronic rangefinder. Not\nusing flash, have lots of room on SD card. Do I just have to live with\nthis?