when you take a picture you are using a camera with an
emulsion based film. You don't have to go very far to
find your subject. You also can determine you f-stop
setting and shutter speed just by making a quick analysis
of your surrounding light.
.....Now imagine having to travel over 200 million miles to find your subject. As you approach your subject you have to make many complex decisions that will allow you to get close enough to your subject.
....After successfully completing your descent through the marshian atmosphere, you are surrounded by a completely different set of environment variables that will require you to consider different things like dust, colors, and position of the sun.