Last month we talked a bit about where “good” photography starts. Briefly, to review, we talked about the need to slow down and observe our surroundings. We also talked about photography and light i.e. good light equals good images. And finally we talked about composition.
Today, as promised, we’ll cover the fundamental basis for how your camera works. I don’t want to get too technical here because, ultimately, my goal is to help you to apply this knowledge to the easiest to use, most immediate tool, at our disposal and that is a cell phone camera.
Since photography is all about light, the key to understanding how our camera works is understanding how the camera captures and uses light to make an image or photograph. One way to understand how a camera works is to look at how the human eye works.
Looking in a very rudimentary way, we can recognize the pupil of the eye, as the hole through which light passes. As the pupil widens more light filters through as the pupil shrink less light filters through. In general, we see better in well lit situations than in dimly lit situations. The eyelid of the eye, when open allows us to see, when closed we see nothing. And finally, the lens just behind our eye refracts the light into the back part of the eye where what we “see” is processed by the optical nerves and electrical impulses delivered to the brain. If everything is functioning properly we see the world in full color and with vivid detail.
Similarly, your camera has three variables that determine how to get the right amount of light for the just the right exposure. These are:
- Shutter speed
Aperture is the hole through which light passes; light passes through the lens to expose the film or camera sensor. Aperture is measured in f-stops. F-stop numbers are represented like so: f1.4, f2.8, f5.6, f11.2 etc. These numbers can be confusing for people, however, because the smaller the number, the larger the aperture or hole through which light passes and larger the number, the smaller the aperture or hole through which light passes. The f-stop number is determined by a mathematical formula involving diameter; honestly I cannot even begin to explain such a formula and while its nice to know such things it’s not completely necessary to understand the formula to understand aperture. Visually speaking, here’s how the inverse relationship of aperture would illustrated:
The thing to understand about aperture, in addition to the fact that the aperture controls how much light passes through the lens of the camera, is that aperture also controls depth of field or how much of your image is in focus.
A shallow depth of field is produced by a wide aperture, which in turn, is represented by a smaller number i.e. f1.4, f2.8, f.4.0. A shallow depth of field will mean that a certain portion of your foreground and background will be blurry or out of focus, the wider your aperture the shallower your depth of field. Using a shallow depth of field produces what is called “soft focus”.
Conversely, the smaller your aperture the sharper your image will be. With a smaller aperture more of your foreground, middle ground and background will be in focus. This is represented by a larger number i.e. f5.6, f8.0, f16.0 etc.
There is a shutter or curtain that covers the film or sensor of your camera. The shutter does not open unless you click the shutter button.
If we want less light to hit the film or sensor then we want a “fast” shutter speed or we want to open and close the shutter for a shorter duration. If we want more light to hit the film or sensor then we want a “slow” speed or we want to open the shutter for a longer duration.
Shutter speed is measured in seconds and fractions of seconds i.e. 1/20 (slow), 1/60 (fast), 1/100 (faster). When day photos with flash or in bright light, fast shutter speeds apply. When taking photos in low light or even at night, slow shutter speeds apply and a tripod is likely in order.
“Fast” shutter speeds stop motion while “slow” shutter speeds blur motion. This is important to keep in mind if taking photographs at a sporting event or assessing whether or not a tripod might be needed to avoid motion blur.
ISO (Sensitivity to Light)
ISO, simply put, is sensitivity to light, whether we are speaking about film or a digital camera sensor. Sensitivity to light means how fast or how slow an image can be exposed using that particular ISO setting or film speed.
As with everything else in photography, ISO is measured in numbers. ISO films and settings can go as low as ISO 25 and in this digital age camera sensors are pushing extreme limits with ISO’s at 25600 and above. Digital cameras typically have a base ISO setting; usually this base ISO setting is ISO 100 or ISO 200. The ISO settings will then double in increments to the highest ISO setting.
The lower the number the slower the film or less reactive to light it is, the higher the number the faster the film or more reactive to light the film is. So ISO 100 film or your ISO camera setting will be best used in daylight situations and for still photography while ISO 800 film/camera setting will be best used in low light situations or for action photography.
Finally, ISO affects film grain and digital noise. Ideally, you should use the lowest ISO setting or film your shooting situation allows in order to get the clearest, grain or noise free images as possible. But for creative reasons and simply because you have to, you may need to “bump up” your ISO to get the results you want.
So there you have it folks, these are the key components to getting good images. Aperture, Shutter Speed and ISO. Here’s a really great illustration highlighting how each of these components works together:
Now the work of putting these three things together to produce great images is in order. Obviously, on a DSLR it is of the utmost importance to understand how to apply these concepts to get what you want if you wish to make the switch from auto to manual shooting.
If you are using a point and shoot camera or your cell phone, these things are helpful to know in terms of pushing the limits of the technology to get what you want.
I will be doing a 45-minute webinar on how to get better photos from your cell phone on March 29 at 12:00 noon. There’s a nominal fee for the session but guarantee you will walk away with some brass tacks on how to use your cell phone to good effect. Here’s how to register for: How to Get Better Pictures from Your Cell Phone.
Until next time