Camera 101

There are many instances when you may want to control exposure speed.  Above are two examples of catching the surf coming in.  The crop of the picture on the left captures the sweeping movement of the waves, while the crop of the picture on the right focuses attention on the textures and subsequent reflections in the water.

The picture on the left was taken to freeze the moment when the bears faced off with the salmon.  In the picture on the right, however, there is no movement to catch, so a slower shutter speed worked great.

If we pour water through our funnel onto a thick sponge, it will take quite a bit of water to fully saturate the sponge.  But if we pour water through our funnel onto a thin slice of paper, we will saturate the paper very quickly.  Your camera's sensor has the ability to be a sponge or piece of paper (or anywhere in between).

That is to say that your sensor can adjust itself to need MORE light to capture an image, or to need LESS light to capture an image.  

So why would your camera ever choose to need MORE light?  

Well, like most things in life, there's a trade off.  ISO stands for International Standards Organization, and it goes back to when cameras used film instead of sensors.  Way back, when I wanted a film that would need LESS light to capture an image (for instance, on a cloudy day, or when I was photographing fast action), I purchased 400 ISO film.  When I wanted a film that needed MORE light (for instance, on a brght sunny day), I purchased 100 ISO film.  Today's cameras have adopted the same sensitivity scale for their sensors.

Essentially, we are wanting to control three functions.  (1) How long does the shutter stay open?  (2) How wide is the shutter open? and (3) How much light does your camera need to take a shot (ISO)?  

You can set each of these independently or in combination.  The control mechanisms for setting them vary considerably from camera to camera.  Some cameras access these features conveniently through a physical knob or button on the top of your camera, and some require you to go into the menu settings.  Check your instruction manual for further details.

When we use these settings in COMBINATION, we have much more power and efficiency in taking our photographs.

Remember, our three main functions are APERTURE, SHUTTER SPEED and ISO.

For each of these, we have three options:

1. The photographer can manually adjust the setting

2. The photographer can lock one setting at a specific value, and/or

3. The photographer can allow the camera to automatically adjust the setting

In some instances, we care very much about aperture, but not so much about shutter speed.  For instance, here is a picture of a sunflower on a sunny day.  In this scene, we have plenty of light, so we don't need to force a longer shutter speed, and we don't need to pick a higher ISO.  The one function we do care about is Aperture, since we want the sunflower to stand out against the background.  Our camera gives us the ability to make these adjustments quickly using the "Aperture Priority Mode."  Using this feature (which is generally controled from a knob on the top of the camera), we will manually set the aperture, and lock down the ISO (in this case, at ISO 100).  The camera will then adjust the shutter speed automatically to capture the correct amount of light.

In other instances, we care about shutter speed, but not Aperture.  In this picture, most of the elements are at a relatively constant distance from the photographer, so aperture is not a big consideration.  At the same time, I was able to use a tripod, so there is no need to adjust ISO to force a shorter exposure.  But what I did want in composing this picture was fuzzy water.  I hoped to get an ethereal look from the waterfall, and that comes from a longer exposure.  Consequently, I set the shutter speed to a bit longer, kept the ISO locked at 50, and let the camera pick the apeture.

When shooting wildlife, I am very concerned with both Aperture (I want the animal to pop out against the background) and Shutter Speed (especially if the animal is moving).  But I am fine with a bit more noise in the picture, since I can edit it out in Photoshop later.  So in this picture, I set the shutter speed and the Aperture, and then the camera automatically adjusted the ISO.

This picture was shot on an overcast day, which means that I had very little reflective light to work with.  The geese were in motion, and I was tracking them with my lens as they flew from right to left in front of me.  As a result of these two conditions, I needed a fast shutter speed to freeze them in flight.  This picture was taken at 1/3200 of a second.  I also wanted to make sure that the brown geeze stood out against the brown background, so I set my aperture to f/5.6.  What did this do to my ISO, which I left on Auto?  It bumped the ISO all the way up to 2200, which resulted in significant noise in the background.  I could go into Photoshop to correct this noise, or I could have shot at a slightly slower shutter speed to reduce the noise.

This picture was taken at the fabulous Petrified Forest National Park in Arizona.  The sunlight was brutally direct and harsh.  I was shooting at midday (rarely a good decision for landscape photography) and there was not a cloud in the sky.  But this is often the case for me, since as an amateur I usually shoot when I have the chance, not when the conditions are best.  So, given the bad lighting, how did I make the most of the scene?  Well, in these conditions, it's easy for a scene to lack any sense of depth.  Since there are few shadows to help provide a sense of three dimensions, I needed to make the petrified log stand out against the foreground and the background, which means I needed a large aperture (low f/stop).  I knew I had plenty of light to work with, so I set my ISO to 100.  I could have set it even lower, but I stuck with 100.  I chose Aperture Priority Mode, set my aperture to f/4, locked down my ISO, and then let my camera pick the shutter speed.  I knew it would be a fast shutter speed, given the excess of reflective light, so I did not worry about using a tripod.

The Forest

Forest scenes are notoriously difficult to capture.  When we are walking through forests, the trees seem so distinct from each other, and the depth of the scene is obvious.  But when take a picture among the trees, the camera flattens the scene, and the trees just seem to meld into each other in a cacophony of branches and shadows.  For me, the absolute best weather to photograph a forest is fog.  Fog in a forest creates depth, with the closer trees being darker and more defined, and the further trees being lighter and fuzzier.  The amount of fog can vary this affect.  Both of these photos were taken with a tripod in order to allow for slower shutter speeds.  Both were shot at ISO 100 to provide the best color and clarity possible.  But the fog in the left picture was thinner than the fog on the right.  Consequently, I used a larger aperture (lower f/stop) in the left image in order to allow blur the pictures in the distance a bit more.  With the thick fog on the right, I did not need the extra blur, so I picked a high ISO in order to capture as much focus throughout the image as possible.  Fog is not always available, so the second best weather for forest pictures is high cloud cover, when there is still enough light to capture the scene, but not so much as to cause harsh shadows.  On overcast days, using a larger aperture (lower f/stop) is a great choice.  

The Coast

These two scenes are similar.  The lighting conditions were significantly different, with the left picture taken on a cloudy day, and the right picture taken on a sunny day.  But despite their similar compositions, my intentions were very different.  With the picture on the left, I wanted to capture the power of the waves, freezing their motion to illustrate impact.  With the picture on the right, I wanted to emphasize the gentle nature of the tide flowing back and forth over the solid rocks.  For the left picture, since it was an overcast day and I was without tripod, I knew I would need a higher ISO, so I locked it in at 2500.  I also wanted to capture as much of the scene in focus as possible, including the waves in the background and the receeding water on the rocks in the foreground, so I went with a small aperture (high f/stop setting).  Since freezing movement was my intent, my most important consideration was shutter speed, which I set at 1/8000 second.  For th epicture on the right, I knew I wanted ethereal fuzzy water contrasted against the sharply focused rocks.  So, I pulled out my tripod, and shot for two full seconds.  This blurred the waves, which in turn emphasized the sharp focus of the rocks.  I locked the ISO at 100 since I was using the tripod.

Wildlife

Shutter speed often takes center stage when shooting moving wildlife.  Aperture is more important when shooting still animals in scenes where they are naturally camouflaged.   With the bear picture on the left, I knew I needed to capture fish jumping, and that mandated a fast shutter speed.  Since I did not know where the fish would jump relative to my lens (farther away or closer), I also preferred a forgiving focal range.  I set the ISO to Auto, and let the camera adjust accordingly.  

With the picture on the right, the hawk was hidden among brown branches, so I needed a narrow focal range to make sure the bird popped out.  I chose f/5.6, as it was the largest aperture (smallest f/stop) available to that lens.  

Notice how the shutter speed for the stationary hawk picture is actually faster than the speed for the jumping salmon picture.  This was actually a mistake on my part.  Since I was using a tripod, and since the hawk was not moving, I should have shot this at a lower shutter speed.  Even though this picture was taken near sunset, I had more freedom to drop my shutter speed than I did.

I have been using aperture, shutter speed and ISO for nearly three decades, and I have still not mastered them.  Your camera manufacturer knows that most people just want to take a good picture, and don't want to slog through instruction manuals to exert the kind of control described above.  So they have created shooting modes or scene modes.  These are pre-set shortcuts based on specific shooting conditions.

Different cameras have different scene modes, and often have different names for each of their scene modes.  Sometimes you select the mode with a dial or knob on the top of your camera, and sometimes you select them through the menu system on the LCD screen on the back of your camera.  Since cameras vary widely on this scene modes, I will just be covering the main concepts here.  Be sure to read your camera's online instruction manual for greater detail (the manual shipped with your camera is probably not as comprehensive as the online version).

Other Modes

There are other modes which sometimes make an appearance on your camera.  

Two of these deal with the amount of light your camera thinks it needs to shoot any picture.  For this example, let's strip away color from your image.  On a bright sunny day, the number of bright parts (pixels) of your picture should roughly balance with the number of the dark pixels.  This is called light metering, and your camera does it for you using the three main features (aperture, shutter speed and ISO).  The exception to this is full-manual-mode, when you do your own light metering.  So on that bright sunny day, your image averages the bright and dark pixels to a nice neutral gray.  Now let's think about a night scene.  At night, there are far more dark pixels than light pixels.  If you camera were to average them out to a neutral gray, the resulting image would be MUCH lighter than you originally see it.  So when turn on Night Mode, your camera knows the scene is SUPPOSED TO BE darker than average, and adjusts accordingly.  On the other hand, you may be taking a picture of a snowy scene during daylight.  In this situation, the scene is supposed to lighter than average, so your camera meters the light accordingly.  

Other common scene modes include Macro (which allows you to focus very close on your subject), and Sunrise/Sunset modes (which will emphasize the reds in your image).