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  • Writer's pictureMark Abere

How to Master the Exposure Triangle (ISO, Shutter Speed and Aperture)

Updated: Dec 3, 2020

Congratulations! You made it to the second part of this mini series! In the last lesson we mentioned a few things that you should consider when starting photography. We talked about...

-What a DSLR camera is.

-Good camera bodies you can start with.

-Portrait lens vs zoom lens.

-Bokeh. 😋

-And the importance of patience!

In today’s lesson we will discuss a few concepts that often give beginner and semi-intermediate photographers trouble. When I ask people why they’ve stopped taking pictures, I've found that learning (or relearning) the foundational concepts can be irritating enough to make people want to give up. Like I mentioned in the very beginning, there is a lot more to photography than what we'll discuss. However this is a great starting point for anybody interested in portrait or casual photography.

Lets begin.

(diagram from

The diagram above is one that puts 3 the major aspects of exposure (ISO, aperture, and Shutter Speed) in relation to one another. Generally speaking, a great picture is a balance of all 3. For the purpose of learning each concept, we will separate them. As you shoot more in manual mode, you'll begin to think of all of them at once and it will become second nature.

Learning Shutter Speed

Shutter speed is the amount of time the camera’s shutter is open, allowing light to enter the sensor.

school girl portrait black and white field
black and white portrait /bmarkphotography

Changing your shutter speed changes two things – 1. The brightness or darkness of your photo.

2. The sharpness of a subject.

Your camera's shutter speed is responsible for the blurr that appears when you’re trying to capture a subject in motion. If we could over simplify things, there are fast shutter speeds and slow(er) shutter speeds.

Shutter speed is measured in fractions of a second. So when we say “faster” shutter speed you have to think in terms of fractions. Between 1/1000, and 1/4 of a second, the “faster” shutter speed is 1/1000, and thus would give you a sharper image.

Gem to remember here: faster shutter speeds lead to darker pictures, but also sharper images. Slower shutter speeds lead to blurrier pics, but brighter pictures.

Last thing about shutter speed: if you think about it in terms of a blink, it may make more sense. When you blink fast, you don’t allow much light into your eye, but your eye can focus pretty quickly. On the reverse, when you blink slower, you can see for much longer, but things begin to loose focus as your eye lids begins to close. It’s the same concept. A slow blink allows more light into your eye, while a faster one allows less light into your eye.

(photo from

(explanation of above diagram. The faster shutter speeds are 1/500 and 1/250... as you get to the slower shutter speeds, you can see that the subject appears to be more in motion. The blink is "slower" so you allow more light into the camera, but catch more of the subjects motion)

Adjusting the ISO

The ISO level determines how sensitive your camera is to light. ISO is a little more straight forward, but there’s a catch. You always want your ISO to be as low as possible. Why? Because higher ISO’s lead to grainer pics.

graduation photo
increased grain due to increase ISO

Rule of thumb for ISO: illuminated area’s require lower ISO levels. Darker areas require higher ISO levels.

If I’m outside during the day, my ISO is typically on either AUTO or 100-200. If I’m indoors and the lighting is not as good, I’ll probably bump it up to 400-500, depending on whether I’m using an alternate light source (a flash) or not. Again the rule of thumb – you want your ISO level as low as possible to avoid noise/grain. As you upgrade your DSLR camera, you’ll realize that the higher end cameras are better at allowing you to increase your ISO level without increasing the grain as much.


portrait field photography
portrait shot / bmarkphotography

The aperture in your camera is the opening in your camera’s lens that allows light to pass through. It’s important because it allows for the depth of the field in your photos and is normally comes with the letter “f” in front of it. Do you remember when we mentioned bokeh in part 1. This setting is essentially what allows you to get that "portrait" effect in your photos.

This chart (below) pretty much explains what you have to understand to be able to master this concept. Larger f stop numbers are used in areas with excess light (similar to aperture speed). The bigger the f stop number, the less light allowed into the lens of the camera, Less Bokeh. On the reverse, on the lower side of the spectrum (left of diagram), you’ll notice that lower f stop numbers allow more light into the lens and thus increase the bokeh.

There’s a limit to adjusting aperture though. Really low f stop numbers tend to give you pictures that are less crisp (similar to aperture speed!!). Thus, being able to balance all your settings so you don’t have to go overboard to get your desired effect is key. It’s also important to make sure you have good lighting when taking pictures so you don’t have to over compensate.

goal in photography is mastering the 3 concepts
engagement shot / bmarkphotography

So there you have it. 3 major concepts simplified. I've included a short quiz, key and explanations that test your understanding of the concepts. Feel free to shoot me an email or contact me on social media if you have any questions.



overexposed beach portrait

1. You're on the beach right in the afternoon and want to take a picture of your friend. You take a picture and look down into the monitor and notice the picture is way to bright (overexposed, above). Which of the following options will NOT help you fix this?

a. Changing the f stop from f/5.6 to f/4

b. Changing the ISO from 400 to 300

c. Changing the shutter speed from 1/400 to 1/600

d. all of the above will help you get desired effect

2. Increasing ISO also increases likelihood of Noise.

The only way to adjust an underexposed pic is to decrease the shutter speed.

a. Only statement 1 is true

b. Only statement 2 is true

c. Statement 1 is true, while statement 2 is false

d. Statement 2 is false, while statement is 1 is true

black male graduation
graduation shot/ bmarkphotography

3. You’re taking graduation pictures and really want your client in focus, but want the schools name out of focus (pictured above). Ideally, where would you want your f stop to be to achieve this?

a. f/22

b. f/2.8 or lower

4. You’re taking a picture of some hair products you need to make a post for. Your pictures keep coming out dark. What can you do to fix it?

a. Lower the shutter speed

b. Increase the shutter speed

c. Increase the ISO

d. a&c

e. none of the above

Key and Explanation

  1. a - All of these other options will help darken your picture EXCEPT decreasing the f stop. Decreasing the f stop will increase the brightness of your picture, which will not help you in this situation.

  2. c- Remember, increasing a camera's ISO increases the amount of noise (grain) in a picture. Statement 2 is false because of the world only. There are multiples way in which you can fix an overexposed picture.

  3. b- Lower f stops yield more bokeh. Period.

  4. a- Remember, lowering the shutter speed will allow for more light. Also increasing the ISO increases your sensors sensitivity to light (but also increases grain).

That's all I have for you, for now. Let me know if you have any questions! If you found this helpful, subscribe to my email list here and be the first to know.



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