i do a lot of low light shots with manual flash (cheap yongnuos) off camera and am trying to figure out a good way to get things sharp. autofocus usually does alright but sometimes there's a lot of hunting and it just fails. manual would be great, but i need some light and find the flashlight trick awkward and obnoxious, especially since there's a freaking focus light already onboard. is there a way to set that light for use with manual focus? thanks.