ISO exercise

I took 9 shots of the back yard on Apeture setting f5 and changed the ISO from lowest to highest setting. I was disappointed that there was not much change.
The shutter speed ranged from 1/13 to 1/400. Even the slow speeds were OK, I must have steady hands. Some deterioration at the high range but not too bad.

This is the fourth at ISO 640, speed 1/80. For those doing the AYWMC I will try to post on FB.