I was just out today shooting a short adventure spot, and we came across a really neat impression in the snow that I wanted to have the talent closely inspect for the camera. Basically, a small grouse or pheasant had climbed out of a hole, and flew away. It left a spectacularly well defined impression in the snow, including wings, body and beak.
To make a long story short, my final product was not what I had hoped. I had trouble focusing on the impression which appeared all white through the viewfinder. The auto focus didn't do any better. Any tips?
Once you have confirmed the focus marks on your lens by measuring with a tape, you can "tape" any subject for accurate focus. Consult charts such as are in the ASC manual to find depth of field distance with near and far extremes.
Creating a "drop shaddow" with lighting might help define a the "impression" you describe in the snow, or alternately blocking the sun or skylight, in effect a "negative key" might make the impression more three dimensional and easier to see in the two dimensions of a motion picture.