Aperture & Depth of Field

In yesterday's session with Sian we experimented with depth of field and how we can control focus by using it. Aperture is how big the opening in the lense is, which determines how much light hits the sensor or film. The eye is tuned to focusing on that within the frame which is sharp, therefor, by using a shallow depth of field and wide aperture, the photographer is selecting a subject in which they think is significant in the image and forcing our eyes straight to it.  It's a bit confusing because the wider the aperture, the lower the F number and a lower F number means a shallower depth of field and more light is let in through the opening. For example, the 18-55mm lense i was using yesterday had a widest aperture of f3.5 which gave me a much shallower depth of field than f22 . The narrower the aperture, the higher the F number which gives you a larger depth of field and lets less light into the opening.

We had a little experiment around the campus, to demonstrate this. I was using my Canon EOS 500D with my 18-55mm lense and had it set to aperture priority......

This one (above) was taken using 1/60sec f/3.5 ISO100

This is showing a shallow depth of field......the middle section of the image is in focus.

                                             This one was taken using 1/40sec f/20 ISO100
                                   Showing a larger depth of field as all of the image is in focus.

Another one demonstrating shallow depth of field. The closest part of the chair arm is out of focus and so is the building outside in the background but the furthest part of the chair arm is in focus. 

1/60sec f/3.5 ISO100

               
            And the same image demonstrating a large depth of field where everything is in focus
                                                                   0"6sec f/20 ISO100



In the following posts, i will experiment more with aperture and post some of my images. I'll also research some photographers who used a shallow depth of field in alot of their work.