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So, photographically speaking, what is exposure?  Sometimes we refer to a picture as an exposure, but that’s not what we’re talking about here.  “Hey, Dana, my memory card only has enough room for a few more exposures!”  No, that’s not what we’re talking about, today.

We want to discuss exposure as the process that occurs in the camera once we click the shutter button.

What Happens When We Press the Shutter?

When we push that shutter button, several things happen resulting in our picture being made.  Our camera’s lens suddenly adjusts its opening (the aperture) to a particular size and the light passes through toward our camera’s sensor.  The shutter, a light-tight barrier or curtain covering the sensor, then opens and exposes the sensor to the light for a particular period of time (the shutter speed) and then closes.

Now our camera sensor’s sensitivity to the light is adjustable through its ISO setting. The higher the particular ISO setting, the more sensitive the sensor will be and the less light will be required to create our photograph.

That’s the exposure process. Whew!

What Can We Control?

As photographers, we want to control and manipulate all the variables in that process because each of them can dramatically affect the way our photograph looks.  So what are the variables again that we can control?

  • The size of the lens aperture
  • the shutter speed
  • and the ISO.

They all work together. In fact, a number of photographers and photography teachers refer to their relationship as the “exposure triangle”.  I think its a useful tool for understanding exposure.  It looks like this:

If you change any one of these factors, it affects the other two and the overall exposure.

Another way to think about exposure is to liken it to a glass of water.  The full glass of water is the exposure, and the water itself is the amount of light needed to make that exposure. So, you can fill a glass several ways …

  • You can fill the glass by opening the faucet wide (the aperture) for a very brief period of time (the shutter speed); OR
  • You can fill the glass by barely opening the faucet (aperture) for a much longer time period (shutter speed); OR
  • You can affect the overall amount of water (light) needed by getting a larger or smaller glass (the ISO).

See how these three factors work together?

Why Not Just Let the Camera Worry About This Stuff?

That’s an awful lot to think about when I just want to take a photograph! Can’t I just set my camera on full-auto or program mode, and let my camera worry about it?

Well, of course you can. But then you’ve surrendered control over all the nuances of the photograph – depth of focus, sharpness, lightness, darkness, whether motion-filled scenes will appear frozen – or creatively blurred to convey the sense of motion.

There’s a wonderful world of creative images out there, and they can be your images!  Just take a little time to understand how to manipulate aperture, shutter speed and ISO to control the image.

I really appreciate you being here! Please leave a message below with your questions or comments. I’d particularly like to know what you’re interested in reading on the Lens Lessons blog.

Now, go shoot.



Welcome! Now Crawl Out of the Box

Welcome to Lens Lessons.  I am really excited to get this blog underway.

So what’s the point of the Lens Lessons blog?

Well, cameras have become so smart that many people just set their cameras on the full-auto setting – you know the one that’s marked on many cameras with a green square (what I call the green box).  All you have to do is turn the camera on and it will do the rest for you.  It decides the shutter speed, the aperture, sometimes the ISO, and whether to fire the flash.  After all, that’s how the term “point-and-shoot” came into being, right?

And some folks are completely happy with that, and that’s okay.

But, I suspect there are a lot of other people who want to crawl out of the green box and create photos rather than simply take them.  And that’s what we’re going to do here on Lens Lessons.  We’re going to share digital photography tips and tutorials so we, and not our cameras, control the image.

I’m thinking initially we’ll cover photography basics – things like exposure, shutter speed, aperture, and ISO.  We’ll talk about that most important photographic element of all – light, both available light and artificial light.

But these are just my initial thoughts.  Most of all, I want to hear from you and what you’re interested in.  I don’t pretend to be a guru, so if you want something that’s outside of my experience we may bring in a guest or two to cover it.  So leave me a comment below, and tell me what you’d like to learn more about.  I’d also like to know whether you consider yourself a beginning, intermediate or advanced photographer.  I want Lens Lessons to be as relevant and useful to you as I can make it.

Now, go shoot!