So this is going to be a real quick, down-and-dirty primer on some basic photography vocabulary and concepts. In recognizing that many of my followers/readers are either not photographers or beginning photographers who may not be familiar with these things, I want to get this out of the way before diving into more technical aspects of photography later on. So if you’re an experience photographer with a firm grasp of these concepts, feel free to sit this one out.
Film Speed (or ASA or ISO)
A film’s speed, is an indication of how sensitive it is to light. You might also see it written as an ASA number or as ISO, they all refer to the same thing. Until 1974, there were many different system for describing a film’s sensitivity, ASA (American Standards Association) being the American method. After 1974, the film speed scale was standardized internationally to what we now know as ISO (International Organization for Standardization). A higher number indicates a film that is more sensitive to light, and therefore requires less light to make a proper exposure. A lower number indicates a film that is less sensitive to light, and therefore requires more light to make a proper exposure. High speed films will have more grain than low speed films. For example, an ISO 100 film is LESS sensitive to light than an ISO 800 film; an ISO 100 film will need to be exposed to MORE light than an ISO 800 film; an ISO 100 film will produce LESS grain than an ISO 800 film. The ISO scale is generally written in 1 stop increments; 100, 200, 400, 800, 1600, etc. We’ll discuss “stops” later in the post.
Aperture
In every camera lens there are tiny little blades that overlap in such a way that forms a circular opening in the lens for light to enter through. This hole is called the aperture. The photographer can control the size of the aperture and the size of the aperture is indicated by “f-stop numbers”, f/5.6 for example. The f-stop number is a fraction that I don’t fully understand, but the f-stop number is inversely related to the size of the aperture i.e the smaller the f-stop number, the larger the aperture’s opening. For example, f/2.8 is a larger aperture opening than f/11. Smaller f-stop numbers (larger openings) allow more light to enter the camera than larger f-stop numbers (smaller openings). Since the f-stop number is a fraction, the scale of f-stop numbers isn’t arranged in a neat and orderly fashion like ISO scale or shutter speed scale; one must simply memorize what the f-stop numbers are.
Shutter Speed
The shutter is the physical mechanism that opens and closes the camera’s shutter button is pressed. When the shutter is open, light is allowed to enter the camera and strike the film. The camera’s shutter speed indicates how long the shutter is open for and thusly how long the film is exposed to light. Shutter speeds can range from as fast a 1/12000 of a second or as long as several hours.
Stops/Stops of Light
Stops of light is a tricky concept to explain on paper, but in short, a stop of light isn’t a measurement, it is a relationship. It is a description of halving or doubling the amount of light relative to a starting point or baseline. For example, if I’ve taken a photo and I double its brightness (exposure), I’ve increased the photo’s exposure by 1 stop. If I take the same original photo and quadruple its exposure, I’ve increased its exposure by 2 stops. Perhaps I can clarify with some examples relative to aperture, shutter speed and ISO because it is an important concept to understand.
Ex. 1: Shutter Speed - Let’s begin with an arbitrary shutter speed of 1/250th of a second. If I double the shutter speed to 1/500 of a second, I have reduced the amount of light entering the camera by half; I’ve left the shutter open and the film exposed to light for half as long as I did at 1/250 of a second. This is a change of 1 stop. If I change the shutter speed from 1/250th of a second to 1/1000th of a second, this is a change of 2 stops; I double the shutter speed once (1/250th -> 1/500th) and I double it a second time (1/500th -> 1/1000th) - 2 stops. It works the same going the opposite way, decreasing the shutter speed (1/250th -> 1/125th -> 1/60th).
Ex. 2: ISO - Like above, let’s begin with an arbitrary ISO of 400. If I double the ISO to 800, I’ve made the film twice as sensitive to light, or I’ve made it 1 stop more sensitive. If I increase the ISO from 400 to 1600, I’ve made the film 4 times a sensitive to light, or I’ve made it 2 stops more sensitive; I double the ISO once (400 -> 800) and I double the ISO a second time (800 -> 1600) - 2 stops. It also works going the opposite way, decreasing the ISO (400 -> 200 -> 100),
Ex. 3: Aperture - Shutter speed and ISO are really simple; to increase/decrease your ISO/shutter speed by 1 stop, simply double/halve your ISO/shutter speed. Remember when I stated above that the aperture scale isn’t neat and easy and that one must simply remember what the f-stop numbers are? Well, this is where that comes into play. To make your aperture one stop larger or smaller, simply doubling the f-stop number doesn’t work, but the general idea is the same. Let’s start with an arbitrary aperture of f/8. If I increase my f-stop number to f/11, I have made the physical size of the aperture smaller, decreased the amount of light that can pass through it by half, thus changing my aperture by 1 stop. If I change the aperture from f/8 to f/16, I have made the aperture even smaller, decreased the amount of light that can pass through by 4, thus changing the aperture by 2 stops (f/8 -> f/11 -> f/16). Again, it works the same going the opposite way, decreasing the f-stop number, making the physical aperture bigger and allowing more light to pass through (f/8 -> f/5.6 -> f/4 - 2 stops).
Exposure Value
Exposure value can be loosely described as a measurement of how bright or dark a given scene or lighting scenario is. The exposure value scale ranges from -6 to 23 with each change in the exposure value representing an increase or decrease in the brightness of the scene by 1 stop. For example, a scene that has an exposure value of 15 is 1 stop brighter (or twice as bright) as a scene with an exposure value of 14. The camera’s light meter, or a particularly practiced photographer, will read the scene, determine what the exposure value is, and compute an appropriate combination aperture, shutter speed and ISO to produce a properly exposed photograph.
If you want to really nerd on a exposure values like I do, check out this link for a full chart of all the exposure values and different combinations of camera settings for each one.
Exposure Triangle
The exposure triangle describes the relationship between aperture, shutter speed, ISO and exposure value. Aperture, shutter speed and ISO each represent one “leg” of the triangle. The three “legs” need to remain properly “balanced” with one another to create a proper exposure and if you make a change to one of the legs, you must make a reciprocal change to one or two of the other legs to maintain a correct exposure.
Alternatively, you can think of the exposure triangle as an equation:
Aperture + Shutter Speed + ISO = Exposure Value
If you change any of the components of the equation, you must change one or more of the other components by the same amount to maintain a correctly exposed image. For example, if I increase my shutter speed by 1 stop, I am letting in half as much light as before. To keep the image properly exposed I need to either increase my ISO by 1 stop (making the film more sensitive to light) or I need to open my aperture by 1 stop (allowing more light to flow into the camera).
Ex. : f/16 + 1/400th + 400 = 15 = f/11 + 1/800th + 400
“This all seems really complicated and nerdy. Why do I need to know any of this when I can just put my camera on automatic mode?” I hear you, I really do, but automatic mode is why all your photos look like shit and not at all what the scene looked like when you were staring at it in person. Having a knowledge of, and being able to effectively manipulate the exposure triangle is what gives you maximum creative control over the final look of your photo; it enables you to take the scene in front of you and capture it in the camera exactly (or almost exactly) as you had envisioned.
So let’s discuss the creative effects of aperture, shutter speed, ISO and why you would choose certain combinations of camera settings over others.
The Creative Effects of Aperture
In addition to controlling how much light is allowed to flow through the lens and into the camera, the size of the aperture also controls how much of your image is in focus. How much of the image in focus is known as the image’s “depth of field”. A wide open aperture will result in a very small slice of your image being in focus (shallow depth of field), a closed down aperture will result in a larger slice of your image being in focus (deep depth of field). That is a vastly over-simplified explanation, there’s a lot more physics and geometry that determine an images depth of field. A shallow depth of field is good for portraits because, as you can see above, it helps the subject stand out from the background. A deep depth of field is good for landscapes or any other time you want as much of the scene in focus as possible.
The Creative Effects of Shutter Speed
Shutter speed is used to control the appearance of motion in an image; a slow shutter speed causes motion blur which can be used to exaggerate motion. Conversely a fast shutter speed freezes motion. That’s all I have to say about that. Well, almost. While not a creative effect, it is a consideration when selecting a shutter speed; camera shake. As your shutter speed gets lower, the likelihood of getting a blurry photo due to your caffeine-induced shaky hands increases. Eventually, you will either need to stabilize the camera with a tripod or, change one of your other camera settings in such a way that lets you use a faster shutter speed.
A slow shutter speed blurs the movement of the train. To see a fast shutter speed, imagine the same train but not moving…
The Creative Effects of ISO
For me, I don’t see which ISO to use as a creative choice. I suppose if you were deliberately hoping to create a grungy type photo you could choose a high ISO film for its grainy look but, If you want clean, sharp images with as much detail in them as possible, then a low ISO film is preferable. If shooting indoors or in another low-light scenario, then you’ll need to choose a higher ISO to keep your shutter speed fast enough to avoid blurry photos. So for me, ISO choice is more of a pragmatic decision; I’ll select which ISO I want to use based on the shooting conditions, how I’ve envisioned the final image to took, and whether I’ll have a tripod available.
So there you have it. Not a particularly excited blog post but I feel it was needed to lay a bit of foundation before I dig into more advanced topics later on. If there’s any questions, comments or concerns, leave them below, email me or DM me on the socials.
Thumbnail image provided by Andrey Konstantinov @konstandy via Unsplash