Chalk Hill Blue, Polyommtus coridon a Chalkhill Blue was perched near side of road. It had settled for the evening. Both the Canon 5D and Sigma were new to me. EF 100 2.8 was impossible for me to focus, so I switched to the Sigma in hopes that I would be able to focus the lens. Nerves in shoulder, elbow and wrist were ruptured from catastrophic shoulder fracture, so it was effort to recover use of arm and hand and desperate hope that I would be able to use the Sigma and camera.