These fox squirrels are both abundant and super approachable in a downtown park in Seymour, IN. I use a Canon 1DX II and a Canon 800mm lens with an AF microadjustment of -3 to hit sharp focus. As the light was changing continually, I used my preferred Autoexposure mode of Auto ISO, and manual aperture and shutter speed to lock both in while letting the ISO adjust for changing light. All of this is mounted on a Wimberley gimbal head attached to a Gitzo tripod. AF microadjust has been a HUGE help in getting the focus sharp. Having tested several of my Canon lenses, all back focused a little and corrections have varied between -3 and -9. Many of my detailed photo technique articles appear on my blog at www.gerlachnaturephoto.com