Most cameras default to adjusting ISO in increments of 1/3 of a stop. This is really more granularity than you need when in the field and simply makes your life more difficult. It's trivial to add or subtract a 1/3 of a stop in post. When shooting, it's far more convenient to adjust ISO in increments of 1 full stop. Dig through your camera's settings and see if there's a way to skip 1/3 and 2/3 ISOs steps. On the D800, the menu item is labeled, "ISO sensitivity step value." If you can't find it on your camera, don't worry about it. It's only a minor convenience, but every little trick to make your life easier adds up.