Hi, ive several years in IR field. Tvernuccio = dust on filter or lens or both (dust reflects alot of IR)be sure filter is spottless, or youll see it. Mayday = Ir light is bouncing around inside the lens barrel. That spot from the apreture. One of my Nikons has it...thankfully my new Nikon doesnt:) Youll have to put up with it. Set camera to the largest apreture and make sure the clear sky isnt ever in the middle of the camera....Throw a stray cloud into the middle if your sky is going to be there. Zooming in will help a little too. It drove me crazy after a couple of years..thankfully, that camera fell and broke and was forced to buy anew. :) Anyone has any IR questions, feel free to ask. :)