Week 4: Exposure

Exposure: Haven’t we already done that?

Well kind of, but what we have really looked at are three of the 4 components of exposure: ISO, Aperture, and Shutter speed.  But, exposure is really the combination of these 3 elements with the existing light of our scene.  Our goal, for the most part is to have the brightness of our image be similar to that of what we see.  I say similar because cameras are limited in the amount of brightness that they can see.  Even though, when we look at a scene with our eyes, we can see detail in the darkest shadows, and in the brightest highlights, our cameras do not “see” the world in the same way.  If there are portions of your image that are very dark, and other portions that are very bright, in our photograph may only show white in the bright and black for the dark.  We can only expose for a certain portion of our image.

Wait, doesn’t the camera take care of this stuff?

Well, yes and no.  Modern digital camera’s do a pretty good job of exposing for average scenes, with average light.  But, photographic scenes are a lot like people, there aren’t very many that are actually — average.  Now, our goal in this site is to move away from average photographs.  So, we have to learn a little bit about how our camera light meters work, and more importantly how, and how often they are fooled.

Fooled?

Yep, fooled.  To be clear, a camera’s meter does a very good job doing what is designed to do.  A camera’s meter is designed to expose your image to what photographers call “18% gray” — what does 18% gray have to do with any of this — 18% gray is an average tone.  If you were to look at a nice fresh green lawn (ignore the color of the lawn), the tone of the lawn is 18% gray.  If you are taking a photograph of something that is average (18% gray) — then your exposure for that subject will be pretty close to perfect.

So, what if our subject isn’t 18% gray?

Your meter will get fooled!  So now what?  Well you adjust.  You over or under expose your image based on what the tone of your subject should really be.  So, for now lets leave it here, and move on to a little mini assignment.  Take your camera, set it on automatic, and lets take some pictures.  Don’t get too excited, we’re just going to take three images.  A white wall, a black wall (or as dark as you can get), and a medium toned wall.  Fill the frame completely with white, then black, then something in the middle.

Simple — talk with you tomorrow

Jason

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