F- stop, The Movie

This video illustrates what was covered in the previous post covering F-stops and should help crystallize the concept.   It also discusses depth of field or that which is in focus.  There’s a direct relationship between F-stops and depth of field in that DOF is determined by the size of the aperture opening and the focal length of the lens, as well as the distance at which the camera is focused.

All else being equal, the larger the aperture or the longer the focal length (telephoto), the shorter the depth of field. A long depth of field (most of the image in focus, close up to far away) is gained by using the widest lens (wide angle lens eg. 18mm- 35mm) with the smallest aperture hole.  The shortest depth of field (a small range of distances in the image in focus) is achieved by using a long lens with the largest opening.

Let’s say you want to take a picture of a flower or a portrait and you want the focus to emphasize the subject with the background all blurry.  No problem, let’s shoot with a long lens and an open aperture (large opening, means what?  Small number F-stop like f/1.4,  f/2,  even f/5.6!)  Very good, are you getting the hang of it?

Ok, now we want everything to be in focus from close up to infinity, let’s say a nice landscape. Easy, let’s shoot with a wide angle lens and close that aperture down to a larger number f-stop like f/16, f/22 or f/32.

The best thing to do is to give this a try or better yet, join me on a SCOUT Photo Expedition and we’ll do it together.

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