Watch the red frisbee and the grass turn into the same muddy yellow.
What's going on
Dogs are dichromats too. Red and green collapse into shades of yellow-grey, so a red ball on green grass is found by smell and movement rather than colour. Acuity sits around 20/75 - softer edges at any distance.
Field of view
You: ~190°
Dog: ~240°
Approximate horizontal field of view, seen from above. The dot is the head.
Human vision