I sold the Nikon 500mm and purchased a Sigma 500mm f/4.5 autofocus lens, shown on my Losmandy G11 mount. I use a 42-year old 60mm refractor as a guide scope, retrofitted with a 1-1/4 inch focuser and a red-dot finder. Both sit side-by-side on a Losmandy plate. This setup was photographed at Harrington Beach State Park in Lake Church, Wisconsin.