The Occasional Shippment

Occasional thoughts from a young adult reveling in the messiness of life.

Exposing It All

I’m officially done with week 3 of my awesome photography class.

Now that the class has covered all of the elements that determine a photograph’s exposure (Aperture, Shutter Speed and ISO), it was time to really put our knowledge to the test. For the first couple of weeks, our assignments were to shoot on one of the following modes: Program, Aperture Priority or Shutter Priority; however, the homework for week 3 required us to use the Manual mode, where we set our own aperture, shutter speed and ISO to properly expose an image.

It really wasn’t as technically difficult as it sounds; there is a nice little meter in the viewfinder that lets you know when your settings will result in a correct exposure. The harder part is realizing that a number of combinations of these settings will create a correct exposure, but that doesn’t mean that the settings will result in the image coming out the way you envision it. That’s the part of the exercise which is going to take some time, patience and practice to master.

However, I learned that sometimes the camera will think that an image is properly exposed based on what you tell it to read in the scene, but even that may not be correct. To circumvent that issue, we learned how to use a “Gray Card.” Essentially, you set your aperture, shutter speed and ISO based on the scene you want to capture and remember those settings. Then, you check the exposure by placing the Gray Card into the scene, focusing on it and adjusting settings as needed to achieve the proper exposure on the card. I’m going to have to do further investigation into why it works, but it has something to do with the camera recognizing that particular gray as a “neutral” and being able to properly expose based on that color.

I may not understand exactly why it works, but the pictures below show that it does. The pictures are of some tulips that are beginning to bloom in our yard. The first picture shows what my camera read as a correct exposure. The second picture, however, shows how making adjustments based on the Grey Card resulted in a more correct exposure. (In this case, I adjusted the aperture, which gave me a deeper depth of field for the shot, keeping both flowers in better focus.)

Even though I can see the difference, using the Gray Card isn’t always convenient (just try propping a piece of heavy cardstock up against some flowers), so the other option is to use a technique called “Bracketing”, which is where you tell the camera to take one shot at the technically correct exposure, then overexpose the next shot and underexpose the third shot (you control how the under/over range).

Correct Exposure (Photo on Right with Camera Settings/Photo on Left with Grey Card):

     

Here is an example of Bracketing:

          

Nugget of knowledge for this week: bracketing is easy; refocusing the lens (and therefore recomposing the shot) is not.

While bracketing is a somewhat automatic process on the camera (I don’t have to set the exposure each time), I do have to refocus the lens and recompose the scene, which was a little frustrating. I typically focus on a particular object, keep the shutter release button held down half way, and then compose the image before fully pressing the button. This process is not easy, especially using a tripod, and trying to compose the same scene three times while bracketing was simply frustrating. Because of this, I’m not sure that I’ll bracket very much, but it was a good exercise.

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This entry was posted on March 30, 2011 by in Photography and tagged , , .

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