When learning digital photography it quickly becomes apparent how important the Exposure Triangle is. There are probably more references to it in articles and online forums than any other subject. What I discovered is that there is one thing to understand the theory (although that takes time!), and applying the principles when out on a shoot. I will attempt to summarise my understanding of the Exposure Triangle so far.
TRIGGER WARNING: It’s also full of numbers. This was a reason why photography felt out of reach for me. I equate numbers with all things technical. In the beginning the seemingly counterintuitive and paradoxical numbering system of aperture mode was confusing. And the number systems that each mode measures is different- but it is slowly becoming clearer (no pun intended!).
Understanding the Exposure Triangle is essential if I want to use manual mode.
The Exposure Triangle consists of:
ISO- The amount of light that hits the sensor in my camera. ISO does not mean “exposure” per se, just to make things complicated (however as I am a beginner everything can be complicated!). ISO has no impact on exposure on its own. It affects the brightness of the image.
Aperture- The size of the opening of the aperture in the lens I am using. A “wide” (more open) aperture has a lower f stop number; a “narrow” aperture lets in less light and has a higher number.
Shutter speed- The amount of time the shutter opens and closes, thus the amount of light reaching the sensor.
To expand on this:
ISO should be set as low a possible depending on other conditions such as light.
The higher the ISO the more “grainy” the image will be. The higher the ISO the less light.
Each time we double our ISO value we need half as much light.
ISO, like the other two parts of the triangle can be manually or automatically set.
Aperture; for a newbie photographer the aperture settings are fiendishly counterintuitive.
The aperture value does not remain constant throughout the length of the lens.
In summary, the aperture value is a measurement of the size of the aperture relative to the focal length of the lens.
Aperture changes are measured in f stops. f1.8 means that the aperture is wider (lets in more light) than if it is at 1/16 for example. Logically f 16 should be wider! However, if I consider that these numbers are fractions then it makes sense- ¼ is bigger than 1/16. The aperture controls how much light is coming into the camera.
“f” means focal length so f2 means the aperture value is 2. If we replace f with the focal length of the lens, say 100mm/2 =50. This means the opening in our aperture is 50 mm wide.
If the focal length of the lens was 100mm, and aperture was all the way open at 50, the aperture value would be f/2. (100/50 = 2). So if the lens was 200mm, divide this by 50 (how wide the aperture can go) = 4. So f stop is f/ 4.
If I want to get a blurred background (bokeh) the aperture needs to be wider, such as f/1.8-f/5.6. For deeper depth of field. i.e. the whole image is sharp; the f-stop can be higher, such as f11-f22, meaning the aperture is smaller, letting in less light. So the aperture I am setting is crucial to how much of the image is in focus.
Shutter speed: The shutter controls for how long light is entering the camera. The larger the number i.e 1/30 sec, 1/50 sec, the longer time light has to come in, more light is coming in. This is a slow shutter speed. This is good when you want to blur a subject, like a waterfall, or it is night time. If you want to catch a fast moving subject (such as a bird) crisply and clearly, you need a higher shutter speed, such as 1/250, 1/1000 etc.
A higher shutter speed lets in less light.
Shutter speed needs to be faster for a long lens, and slower for a shorter lens. Shutter speed should be at least as fast, or faster as the length of my lens, the longer the lens the more I need to compensate for that i.e. 300mm lens needs double that in shutter speed 1/600 secs or higher.
Always try to use a tripod to reduce camera shake!
Aperture and shutter speed need to be balanced with each other.
There is an internal meter that calculates this automatically in automatic mode if we are using that.
STOPS. Is a measure of f stops or shutter speeds. Can mean half as much light, or twice as much. So every time I move the aperture (in stops) in any direction to get more or less depth of field, I move the shutter speed in the opposite direction by a similar number of stops to make them balance. If I cannot open the aperture any wider, I turn to ISO. I move the ISO by one stop, from 200 to 400 say, which means I can now have a faster shutter speed.
Putting it all together, if you have a bright day and want to shoot a bird sharply, you would have a low aperture f stop, a high shutter speed, and a low ISO.
Most experienced photographers advocate using aperture priority when learning photography, meaning I am in charge of the aperture, and the camera automatically sets the correct shutter speed, and ISO.
In terms of learning, a useful approach is to take several shots of the same subject, but increase and decrease the f-stop, and then review afterwards to see which one produced the best image. And do the same for shutter speed and ISO too. Then I will be able to shoot in manual mode with more confidence. I am still shooting mostly in aperture mode.
As always I looked widely for information, and am indebted to these You Tube videos by Mark Williams.
I also loved the many graphics available that present this information in a logical simple manner. This is from Pinterest:
So there you have it. As with all things photography, it only makes sense if you keep going out and practicing- I have experienced a serious disconnect between theory and practice at times, but I am beginning to know what to look for in terms of these settings dependent on the situation.
Comments