WK 3: Depth of Field: Walking. I seem to always go for an aperature that is wide open when shooting wild life…I think the blur makes the subject stand out. I took this at our zoo and the large aperature also hid the humidity on the aquarium. This little dart frog walked slowly right in in the center of the aquarium and them JUMP and he was gone. These little dart frogs are a challenge to get a good picture of.