However the usual method is to get an old fashioned shiny chrome hub cap, place that on a level surface (with an electric heater under it to stop the thing fogging over) and place directly over it a camera fitted with an ordinary lens. The reflection gives all sky coverage with minimal blockage from the camera & support. You can get custom made shiny chrome "hub caps" that distort less than ex-Morris Minor types, if you can be bothered to pay the price.