Lecture 15: Cameras & Lenses (24)

I noticed that in all the other pictures shown in this batch of slides the background appeared quite blurry, except for this one. Is there a particular reason to this? Perhaps it’s because the subjects in the other ones are all very close to the camera, but in the last picture the little girl riding a tricycle also appears to be quite far from the camera. Why is that one blurry but not this?


@DanCubed There are two reasons! Depth of field (which is inversely proportional to bluriness) increases with wider focal lengths. 18mm is considered an ultra-wide lens, so it has trouble making blurry backgrounds.

Additionally, f/8 is a pretty small aperture that you can only really use during the day time since it doesn't let through much light. Small aperture also leads to a wide depth of field and thus a non-blurry background.

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