Recently a friend asked me why anyone would want to use a camera in Manual mode, when the camera takes great pictures in Automatic mode? While I could not disagree that the camera can take a great picture in Automatic mode, I answered that in manual mode the camera was taking the picture that I intended. The next several posts are intended to better answer that question. While not intended to be the end all be all explanation of using your camera in full manual mode, it is intended to introduce the concepts in a way so that it is easily understood and not intimidating. I am not going to talk about meters, or histograms. Check out Bryan Peterson‘s book Understanding Exposure to really take this to the next level. Many of the concepts you already understand, we are just learning a new vocabulary!
In photography, exposure is defined as the amount of light that reaches the sensor or film in your camera. Why is this important? Because photography is the recording of light – graphy meaning to write, and photo meaning light – making our hobby all about the “writing of light”. For each image that we create there will be one ideal amount of light that will allow us to properly record this scene. Your camera will have settings for Aperture, Shutter Speed and ISO that determine how much light is used to create your exposure. Aperture determines the amount of light that enters the camera, shutter speed controls how long that light will enter the camera, and ISO determines how sensitive your sensor is to that light.
Aperture
The aperture is actually the physical mechanism in your camera lens that opens up to allow light to reach the sensor. It acts much like the iris and pupil in your eye. The bigger the opening, the more light comes through. The smaller the opening, less light comes through. Seems pretty straight forward doesn’t it? Well it actually is! You already understood this concept, so lets take it one step further and learn the lingo that photographers use to verbalize this. That is all we are really learning, a new vocabulary! An aperture is measured in what is called an f-stop, such as f/8.0. So what do different f-stops do? Simple – different f-stops let in different amounts of light. An f-stop of f/2.8 lets in a lot more light than an f-stop of f/22. That is all you have to remember about how this physically works. If you want more light then you want a larger aperture (opening), meaning a smaller setting (f/2.8). If you want less light then you want a smaller aperture (opening), meaning a larger setting (f/22).
Each time you “open up” your aperture, you double the amount of light that reaches the sensor. So if you change from f/8.0 to f/5.6 you have doubled the amount of light. If you change from f/5.6 to f/4.0 you have once again doubled the amount of light that you are letting in. Selecting to shoot at a large aperture (f/2.8) lets in a lot of light giving you have the option of shoot at faster shutter speeds, then if you had selected to shoot at f/22. As you can probably start to guess by now, as you open up and let in more light through the aperture you can “stop down” on your shutter speed.
Shutter Speed
A cameras shutter speed is the amount of time that the sensor or film is exposed to the light that is entering a camera. The sensor or film is hidden behind a pair of curtains that effectively “hide” it from the light. When you press your cameras shutter button one curtain will slide across and reveal the sensor/film, exposing it to the light. The second curtain then follows along and once again hides the sensor from this light. Our shutter speed settings are measure in time – how long the sensor or film is exposed to our light. Just like with your aperture opening or closing by a stop either doubles or halves the amount of light that is recorded. For example, if you switch from 1/500 of a second to 1/1,000 of a second you will be now be recording exactly half as much light. Had you switched from 1/500 of a second to 1/250 of a second, you would have recorded twice as much light! It really is that simple!
ISO
A digital cameras ISO setting is no different then the ISO for a roll of film. At higher ISO settings the media,whether is is a digital sensor or a roll of film, is more sensitive to light, meaning that you need less light to create a properly exposed image. With an ISO setting of 100 you would need twice as much light to record a scene than if you were using an ISO of 200. ISO controls how sensitive our media (film or digital sensor) is to light.
An Example
Have you ever filled a glass of water at your kitchen sink? Lets try this! Take a glass out of your cabinet. It can hold a specific amount of water correct? Think of getting the glass filled to the rim as being our ideal exposure, and the water as our light – we don’t want too much water (overexposure), or too little water (underexposure). Now hold that glass under the faucet and turn the water on at just a trickle – the tiny amount of water coming out is like our aperture setting of f/22. At this pace it takes one full minute to fill the glass of water. Now lets “open up” our faucet (aperture) so that twice as much water is coming out of the faucet. Doing this is just like when we open up the aperture setting on our camera by one full stop, to f/16. This time our glass fills in only 30 seconds! By letting twice as much water enter the glass we cut the time it took to fill the glass in half! How does ISO play into this example? ISO is kind of like the size of the glass – a bigger glass takes more water to fill, just like a lower ISO setting takes more light to create the proper exposure!
Exercise
Ok, lets grab that camera out of your bag! Put it into “M”, or “Manual” mode and play around a bit with the settings. Start by simply taking a picture of anything at all, and then “chimp” the display on the back of your camera. “Chimping” is the technical term that photographers use to define the process of looking at our LCD display after taking a picture and going “Ohhhhh” and “Ahhhh”. Is it too bright? Too dark? Adjust the three setting that we have discussed until you get the image to look just right. Now that you have a nice exposure pick a setting (anyone will do) and change it to either open up or close down one full stop. Now pick one of the other 2 settings and change it so that you still will get that nice exposure. After a few tries you should be able to to nail it on the first try. Keep experimenting until it feels like second nature. Walk around the house, taking photos of different subjects in different lighting conditions. You want to reach a point that you are making these changes without even thinking about them. I thought about adding example photos to this post, but decided against it for one simple reason: I want YOU to take the pictures and see the results for your self. This is the best way to learn! As you do this exercise do you notice that there are actually several different combination’s of setting that give you a correct exposure? This observation is going to be key to unleashing your photography, and we will spend much time on this in the very near future!
Summary
In this article we talked about what these three different setting do. Over the next couple of days we will explore each of these settings from a creative point of view, to learn why we choose one setting over another! And this is where the fun begins, as this is where we will begin to explore how to use these tools to achieve the images that we see in our minds eye.