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Pulling out all the Stops!

Well, sort of…

In this post, we will be discussing the concepts of stops.

Stops

Are a unit of measurement referring to light in any particular photographic exposure. A stop of light is either the doubling (+1 stop) or halving (-1 stop) of the amount of light entering the camera. Stops can be thought of as a universal unit of an exposure because it can be applied to any of the three exposure settings. For example, if a photographer says they are going to ”increase the exposure by 1 stop,” that means they will adjust one of, or a combination of exposure settings to allow twice as much light to enter the camera.

It may sound confusing, so here is a visual to help.

photography-chart-web.png

The exposure triangle is common way of connecting the three parts of an exposure. Personally, if find the triangle confusing. I prefer the above horizontal graphic instead. It is a representation of how each exposure setting controls light and their specific effect on an image. Looking at the graphic, the left side represents settings that allow less light to enter your camera which will result in a darker image. To the right side, the settings will allow more light to enter the camera and create a brighter image.

ISO

I am going to start with ISO because it has the easiest numbering system to understand. The lower the ISO number, the less sensitive your sensor is to light and the higher the number, the more sensitive it will be. These days, most cameras have a base ISO of either 50 or 100, with the numbers doubling with ever increased stop. So starting at ISO 50, the full stops would be 100, 200, 400, 800, 1600, 3200 and so on. For example, if you were to add 3 stops of light from ISO 100, you would double the ISO to 200 (1 stop), double again to ISO 400 (2 stops) and double it a third time to ISO 800. If you are shooting at ISO 1600 and you want to reduce 1 stop of light, you will divide by 2 and have ISO 800.

Shutter

The concept of stops in relation to shutter speed is pretty simple as well. The faster the shutter opens and closes, the less light will be allowed to hit the sensor, resulting in a darker image. As you may know, shutter is measured in seconds or fractions of seconds. For example, if you adjust your shutter speed from 1/500 of a second to 1/1000 of a second, you are reducing the amount of light by half which equals a 1 stop reduction in light. If you want to increase your shutter speed of 1/100 by 1 stop, you would double it to 1/50 of a second. If a shutter speed of 1/2000 is too dark and you want to increase the light by 2 stops, you would to double the shutter to 1/1000 (1 stop) and double it again to 1/500 (2 stops). Shutter speed math gets even easier when you start working with long exposures. A 2 second exposure is 1 stop more light than a 1 second exposure because the length of time the shutter is open is doubled. If you are shooting a 10 second exposure and you want to increase the light by 1 stop, you would double the exposure to 20 seconds.

Aperture

Aperture is the adjustable opening found inside of a lens. It is made up of several overlapping blades as seen in the image above. The easiest way to understand aperture is to equated it to the pupil of an eye. The larger the pupil, the more light enters the eye. The smaller the pupil, less light will enter. The numbering system is where aperture gets a little bit confusing. It consists of whole numbers and decimals, which are referred to as f-numbers. To throw another wrench into the aperture numbering system, the smaller the number, the larger the opening. Referencing the graphic above, you can see that an aperture of f/1.4 is a large opening which lets in lots of light. On the left side, you see the aperture of f/32. It lets in very little light since it is a small opening. An example of a 1 stop reduction of light would be moving from f/1.4 to f/2. A change from f/11 to f/5.6 would be and increase of 2 stops of light. The first stop would be to f/8 and the second stop would be to f/5.6.
There is a way to remember these seemingly oddly chosen numbers. First, look at the set of whole numbers and decimal numbers separately. The whole numbers would be 2, 4, 6, 8, 16, and 32. The decimals are 1.4, 2.8, 5.6, but then turn into the whole numbers 11, and 22. Did you happen to notice a pattern? Both sets of numbers double as they increase, with the small exception of the increase from f/5.6 to f/11. Keep in mind, full stops alternate between whole numbers and decimals until they reach f/11, where they continue as f/16, f/22 and f/32.

I will go into more detail about each part of the exposure triangle in future posts.

If you have any questions or comments, leave them below or feel free to send me an email