Understanding Aperture

large depth of field 

small depth of field 

what is aperture?  The size of the opening in the lens that permits light to hit the film/digital sensor

How does aperture work in the camera? Aperture is measured in f-stops, it separates the subject from the background a low f-stop allows more light to enter while a high f-stop allows for less light to enter

in the photo?  the subject is in focus while the background is blurry and out of focus.  

the relationship of the exposure triangle? The ISO in the camera typically remains the same while for aperture the shutterspeed must increase if you're inside and decrease if it's outside.