Foundations of Photography: Exposure

Class Taken By: Kiko Doran

Taught By: Ben Long

The two basic elements of exposure are shutter speed and aperture. Shutter speed is measured in time and aperture is denoted by an f-stop number. Both shutter speed and exposure control how much light hits the sensor of your camera, thus affecting the exposure of the photo.

While I’m at it the instructor of the course made a very interesting distinction about “taking” pictures. He talks about his grandmother always referring to having her picture “made” when she got her portrait done. His feeling is that a picture is not taken because it doesn’t exist in the universe until you make several decisions about the photo before “making” it.

Auto is the least flexible setting for your camera as it makes all the decisions for you when you take a picture. Program mode is next most automatic photo but gives many options to override the auto settings.

When it comes to exposure there is a reciprocity that happens between shutter speed and aperture. If you make your shutter speed a full stop slower, the aperture will close one stop to compensate for the amount of light in a given scene. This is the process that happens when shooting in shutter priority mode. This is very effective when shooting moving objects that you want to freeze (fast shutter) or blur (slow shutter). My camera (Nikon D90) tells me when I’m at risk for either under or over exposure by indicating either HI or LO in the aperture indicator portion of my viewfinder.

When shooting in aperture priority, a larger number lets in half as much light as the stop below it. The aperture also affects the depth of field of the shot. The smaller number has a smaller depth of field and is useful in portrait shots where you only want the subject in focus. The larger the number the larger the depth of field and the shot is more completely in focus which is very useful in landscape shots. The aperture setting is critical in helping people be able to read your shot the way you intend it. Another key point I learned about aperture priority is that when shooting with a large depth of field, the range of focus bookends the focus point. When shooting a horizon, it doesn’t generally make sense to focus on the actual horizon because you end up wasting depth of field beyond the horizon. If you pull back your focus point, you get a more crisp foreground.

This class has really helped me understand how to set my camera to get the shot I intended.  I have taken thousands of photos I have never even looked at.  I went back and used some old photos to get some varied subjects.  When I got good shots in the past it was more luck than anything.  My understanding of exposure has grown by leaps and bounds from watching this short class.

The following shots are intended to show how the aperture setting affects depth of field:

The next shots used fast shutter speeds to stop time with a moving subject:

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