uiuiko

I was in bright mid-day full sun and the shutter speed never got faster than 1/500. I have found that I can change the ISO to 400 and get faster shutter speeds in sunlight, but then extremely slow in even a bit of shade. I previously had ISO on auto; was I wrong to expect that the camera would change the ISO for me when I set the shutter speed?

I may have misspoken a bit; I'm new to this. When I choose shutter priority and set the shutter to 1/1000, the aperture indicator in the viewfinder flashes, which I understood to mean "underexposure"; I was probably wrong to say it couldn't focus. I'm confused because so many reviews say this lens is great for wildlife photography, but if the max aperture it allows isn't sufficient for a faster shutter speed I don't see how it can be. I did try resetting the shooting menu but that didn't seem to make a difference.

I just bought a D7500 with the Nikkor 200-500mm zoom lens. It's my first step up from point-and-shoot and is primarily for wildlife. I took it out this morning to test and found that it won't shoot at any shutter speed faster that 1/500. I'm using all auto settings at this point, and I was out on a clear sunny day, much of the time in open fields. When I tried shutter priority and set the shutter speed to 1/1000 I just got the flashing indicator that it couldn't focus. Is there a limitation I don't know? A setting I'm missing? Thanks...