I love the Christmas season. I always have. A big part of it has always been the church services with the choirs and the kids singing and doing hilarious stuff. I remember myself playing a shepherd or an angel when I was a kid. And my wife and I both seem to remember getting a little paper bag full of peanuts, a “Christmas” orange, and a few pieces of candy (the peanuts were rarely eaten).

These days it’s not all about the bag of treats, but about being together in celebration. It was fun to take the time yesterday to take a few photographs of the morning church service – so much action with all the kids running around. One kid made a break for it and was crawling around under the benches.

My wife sang with the church choir this year and (because she sings the most beautifully) was chosen to solo over top of the choir for one part – just awesome!

I hope everybody reading this has a wonderful Christmas!  -m

We miss you already, old girl!  -m

But when we talk about exposure in photography, we usually aren’t just talking about an abstract concept, but rather the means by which we control exposure. It is rather useless to state that we “exposed a sensor to light” unless we can somehow express how much light the sensor was exposed to. And THAT is essentially what we’re getting at in a discussion of exposure.

Now, to start with, it is important to know that a digital sensor is a blank slate to begin with. In fact, you can think of it as a BLACK slate, and a sensor that receives NO exposure will produce a digital file that is BLACK (try leaving your lens cap on while pressing the shutter button, like I did for figure 1.1). We could call this the most extreme form of underexposure. 

But when a sensor IS exposed to some level of light, that light builds up over the duration of the exposure to produce areas of varying brightness throughout the image. And so an area of the sensor that is exposed to more light than another area will appear brighter than that area. If the sensor is exposed to too much light, eventually the entire image area will move away from black and become pure WHITE. 

And so we have to be concerned not only with exposing the sensor to light, but with exposing the sensor to the right amount of light. And this is where we leave the simple concept behind and venture into a more practical and complex exploration of the methods of controlling exposure.

To start with, a digital sensor has a fixed sensitivity to light (I know some will say this is not the case, but, strictly speaking, it is, and I’ll explain why). That is, it takes a specific amount of light to “fill up” a sensor’s photosites and produce a pure white image. The following “photograph” was taken of my office, but the sensor received so much exposure that the entire frame became pure white. We could say that the entire shot was “blown out”, that is the sensor filled up to its capacity and no image detail is discernible.

Obviously, if we are to be successful photographers, we’re going to need to find some way of limiting the amount of exposure our sensor receives, or the amount that it needs to receive. And the history of photography has been essentially a process of developing more sophisticated ways of doing just that.

I also made the points that light levels vary depending on where we are and when and that not just ANY exposure settings will do. Remember, our bath tub is a certain size and “correct exposure” depends on filling it the “right” amount (I use the “quotes” because the terms are rather subjective in the end). Let me say just a few more general things about exposure before carrying on with more detailed discussions of aperture, shutter speed, and ISO in my next few posts.

It may be obvious that light is what forms an image on a camera’s sensor, but we know from the bath tub analogy that there IS such a thing as TOO MUCH or TOO LITTLE light when it comes to exposure, and so if we had no way of controlling how much light came into the camera we’d have a difficult time doing photography. Let me go on now to say that “correct exposure” is always some combination of aperture, shutter speed, and ISO. But each of these three parameters is highly adjustable and which combination is the “correct” one will depend on how much light is available and what sort of result you are looking for.

Let’s elaborate on the bath tub analogy.

Turning the faucet on only half way allowed us enough time to get a few things done while the tub filled up. But obviously we could have turned the faucet on full blast to fill the tub up faster, or turned it lower to allow ourselves even MORE time while it filled. Each of these combinations allowed us to achieve our goal of a full tub, but each combination was used for a different purpose. That’s like photography. Aperture, shutter speed, and ISO each have their unique effects that we can manipulate to fulfill a creative purpose. Further, in any given situation different combinations of the three can produce identical exposures, but the images produced may look strikingly different. Let’s take a quick look at how each of these parameters contributes to our exposures.

Our Aperture is that hole that allows light to pass through the lens and into the camera. Obviously, a larger hole will allow more light to pass through than a small hole (just like an adjustable faucet). When light levels are very low we have the option of opening that aperture up to its widest to allow the maximum amount of light to flow through. When light levels are very high, as in noon-day sun, we may need to close the aperture down a little so that too much light does not flow through and cause overexposure. The aperture has another effect which is too cool to talk about here, so I’ll discuss that in a post all about aperture.

Now, even though light is passing through the aperture of the lens at all times, it still is not allowed to strike the sensor to form an image until the shutter opens up. Pressing the shutter button to open the shutter is what allows the light to finally strike the sensor. By manipulating Shutter Speed, we control the amount of time that the light is allowed to strike the sensor to form the image. As with aperture, if light levels are low we may choose a lower shutter speed to allow light to strike the sensor for a longer period of time.

Let me stop here for a moment and say that Aperture and Shutter Speed are really the two most important parameters when it comes to the appearance of your photographs. In fact, you can think of exposure in terms of the following equation:

aperture (amount) x shutter speed (time) = exposure

Now, I said that ISO is the sensitivity of your sensor to light, kind of like the size of the bath tub. So we can think of ISO as the amount of light that we need for correct exposure. It used to be that ISO was a function of the film that you used, and so loading a roll of film meant that you were limited to that particular sensitivity for the duration of that roll. But with digital cameras we have the opportunity to adjust ISO on a shot-by-shot basis. This is why we consider ISO much more integral to our discussion of exposure than we used to. Again, to put this into perspective, in low-light situations we may be forced to choose a high ISO setting to make our cameras more sensitive to light if we are to get proper exposure.

In the next post I’ll get into more detail about Aperture settings.   -m

Thanks, guys, for inviting me to a great party. I can’t wait to show you the rest!  -m

 1.  Getting in close is a great way to photograph flowers or plants. This allows you to eliminate other competing elements in your composition and focus attention on the details of a plant’s structure. Getting this close will probably require a macro lens or a macro setting on a compact camera. These features allow you to achieve focus at very close distances (sometimes focus can be obtained on the front element of the lens). If you can’t afford a good macro lens, try picking up a set of Kenko® extension tubes for your SLR system. This set of three tubes can turn any lens into a macro lens for extreme close-up.

 2.  Wide apertures will allow you to isolate your subject against a blurring background. But at close range, sometimes this “depth-of-field” can be TOO shallow and you may have to close down your aperture to gain a little more. In the shots I’ve included, I was going for a more abstract look and so I wasn’t very concerned about sharpness.

 3.  Overcast skies provide better lighting than direct sunlight. It tends to be more even and lower in contrast, and color will be easier to manipulate in post-processing. On sunny days, look for areas of open shade to provide shelter from direct sunlight.

 4.  Using a tripod can help to get the shot, although I rarely even bother. I shot handheld for all of the images below (but then they aren’t particularly sharp, are they?). If sharpness and precise composition are your goals, mount your camera on a tripod. This is especially critical if you are stopping down your aperture for more depth-of-field, since this will result in slower shutter speeds. You may also need to shelter your subject from the wind to prevent it moving while the shutter is open.

Most people prefer to represent nature a little more realistically, while I like to take a more abstract and artsy approach. I used the shallowest depth-of-field that I possibly could, and composed for more abstract representations of my subjects. A heavy addition of grain in Lightroom helped to create more of a ‘fine art’ style. Muting some of the colors also helped me to soften a few of the images.  -m

Once I opened the photo in Lightroom, I decided to brighten up a little, then crop it down to enhance its symmetry. This was a good start, but I thought I would experiment with a black & white conversion.

Tapping ‘v’ in Lightroom desaturated the photo. I could have done this simply by dragging down the saturation slider in virtually any editing software. The problem with this simple method is that it most often leaves a photo looking drab and lifeless, without much contrast at all. This is because, while the color differences in the original photo created pleasing contrast, the tonal differences were not great enough to be rendered with much contrast once the color was removed.

One solution to this would be to simply bump up the ‘contrast’ slider. But I can take more control by manipulating the way the colors are rendered to black & white. I used the B&W panel in Lightroom to adjust the brightness levels of the different color ranges in the photo.

With this method, Lightroom actually uses the color information in the photo to create a black & white. It’s very much like using color filters over the lens to control the rendering of different color ranges into b&w. These adjustments allowed me to get much more contrast in the grasses, darkening them down to help the concrete stairs and the subject stand out to the viewer. This is basic ‘figure and ground’ theory – helping the subject to stand out against its background aids the viewer in interpreting the photograph. Remember that the brighter areas of an image tend to draw more attention.

I added a few more subtle touches and a little bit of film grain to finish it off. Now help me out a bit: Who is this guy and where do you think he’s going?