Honeybees with a D500 and extension tubes

I have been playing around with extension tubes and seeing just what my Nikon D500 is capable of. And what I am capable of for that matter. The below images were all taken with a D500, 50mm f/1.4 Nikon lens, and an extension tube. Settings posted with each image. The first 6 were done with natural light so I could see just how far I could push the ISO. The final 3 were done with a SB-700 speed-light off camera via TTL cord. The flash was diffused but the light still came out a bit harsh, probably because it was only about 16 inches away from each bee.  

ISO 1600 50mm f/11 1/1600s

ISO 2000 50mm f/11 1/2000s

ISO 2000 50mm f/11 1/2000s

ISO 5000 50mm f/16 1/4000s

ISO 5000 50mm f/16 1/4000s

ISO 5000 50mm f/16 1/6400s

ISO 100 50mm f/16 1/250s; Flash 1/4 power

ISO 100 50mm f/16 1/250s; Flash 1/4 power

ISO 100 50mm f/16 1/250s; Flash 1/4 power