Understand Exposure in Under 10 Minutes


DPS-Annie-Tao-Exposure-article-perfect-exposure-exampleThere are countless Photography books and classes that explain exposure, yet after reading or attending them, your photos may not have improved because…well, let’s be honest… some of us Right-Brainers aren’t super technical!

I recently taught a small photography class to newbies. I thought hard about how I could explain exposure in the simplest way possible. I found that a parallel example of something relatable was the best way to convey the different aspects that impact exposure.

I tested this theory by explaining exposure to my 8-year old daughter and then quizzed her. She proved the theory was a success by grasping the concepts within 10 minutes. So I’d like to share my lesson with you so you can understand exposure in under 10 minutes!

A 10-minute lesson that will change your Photography

Your DSLR camera is like your head with the LENS being your vision and the camera BODY is your brain. Your vision sees things and your brain records the details.


Just like when you look at something – let’s say, a flower – your eyes see it and send information to your brain that the flower has long petals and that it is yellow. If you looked at it too quickly or it was too dark, for example, the information your brain records is compromised.

The “exposure triangle” is about how 3 things — aperture, shutter speed and ISO — work together to provide enough light for your brain (the camera) to record what you see. You need the right combination of these 3 components to have perfect exposure.


Good exposure

For example, if you don’t let in enough light, you won’t see things very well because it’ll be too dark (underexposure).


Too dark, or underexposed

If you let in too much light, then it’ll be too bright and you can’t see a lot of the details (overexposure).


Too bright, or overexposed

APERTURE = how WIDE you open your eyes

A small aperture (a large f-stop or f-number, like f/22) is like squinting. A large aperture (a small f-stop or f-number, like f/1.4) is like having “bug eyes”.

Quiz:  If you are shooting in low light, how wide do you open your eyes? Will you see well at night if you are squinting (small aperture)?

Quiz:  What happens on a super bright day if your eyes are wide open and they’re open for a long time (slow shutter and large aperture)? Can you see well then?


Aperture is how wide you open your eyes – bug eyes, or squinting

SHUTTER SPEED = how LONG you open your eyes

A fast shutter, like 1/1000th of a second, is blinking super fast. A slow shutter speed, like 2 seconds, is keeping your eyes open and then blinking. The thing to remember is:  your brain is recording everything when your eyes are open. So if you or something you’re looking at is moving, and your eyes are open a long time (slow shutter), then your brain will record a blurry image.

Quiz:  If you want a crisp shot of someone jumping, how long do you need your eyes open? What will freeze the shot:  a quick blink (fast shutter) or a slow one (slow shutter)?


ISO = special glasses

ISO = special glasses that help you see in the dark

ISO is like the opposite of sunglasses. Let’s call them MOONglasses!  😉

The higher the ISO, the thicker your moonglasses, so the more you are able to see in low light. You need thick moonglasses (high ISO) when shooting indoors or at dusk. You need very thin moonglasses (low ISO) when it’s a sunny day.

Quiz:  do I need thick, thin or medium moonglasses if I’m shooting at the beach on my lunch break?

All 3 of these things work together

Here is an example:  You are photographing your sleeping cat who is snuggled on the couch. There is not much light coming through the windows or additional ambient light. To see well, you have medium-to-thick moonglasses on (such as ISO 600). You need to have your eyes open pretty wide (large aperture, such as f/1.4). However, you don’t have great vision (you have a kit lens that only goes up to f/4.5), so you need more light to see. Thus, you leave your eyes open longer (slow shutter speed, such as 1/30th sec).

Final Quiz:

  1. In the same scenario, your cat notices you are snapping photos, so she starts walking away and leaps off the couch. You still want to photograph her. Which would you change:  how open your eyes are (aperture), how long you leave your eyes open (shutter speed), or thickness of your moonglasses (ISO)?
  2. If you increase your shutter speed because you want to freeze the image, what else would you need to change? (If you changed nothing else, the image would be too dark because you let in less light.)

Once you get the basic concept of exposure and how the three components of the exposure triangle (aperture, shutter speed and ISO) work together, turn your DSLR camera to “manual” and practice the specific settings based on different circumstances.

Want more on exposure?  Try these:

Read more from our Tips & Tutorials category

Annie Tao is a Professional Lifestyle Photographer in the San Francisco Bay Area who is best known for capturing genuine smiles, emotions and stories of her subjects. You can visit Annie Tao Photography for more tips or inspiration. Stay connected with her on her Facebook page

  • J

    Love, love, love this explanation. Thank you

  • jumara

    very good explanation.i’ve read lots of explanations but no one ever mentions focus along with the other 3.please say something regard focus.is it because it is a non issue?thank you

  • Doninnh Bump

    Very helpful site

  • Annie Tao Photography

    You are very welcome!

  • Annie Tao Photography

    That is fabulous! For those who aren’t there yet, MOOD is something you can create in your images once you’ve learned exposure because having the image slightly over- or under-exposed can change the mood of an image!

    Happy shooting, Jami!

  • Annie Tao Photography

    Focus is definitely an issue when it comes to the Exposure Triangle. Perhaps others don’t mention it because it’s more about the shutter speed setting, but to me, since shutter speed is one of the three parts of exposure, focus needs to be mentioned.

    I actually love showing motion blur, so having a slower shutter can create a pretty cool effect. You just need to hold your camera very still (ideally using a tripod), so everything around the motion is sharp.

  • jumara

    so would you set your iso then shutter speed your appeture and lastly check for focus thru your viewfinder and make adjustments by turning the lens to focus?thank you in advance.

  • Annie Tao Photography

    What a great question, Jumara!

    I always start with ISO.

    For images that have motion in it (whether I want to freeze the movement or have motion blur), I would set the ISO first, then shutter speed, then aperture.

    For regular images that don’t have motion, I would set the ISO, then aperture, then shutter speed last.

    On a client photoshoot, I only check the viewfinder from time to time (not often). It’s more to check if the exposure is where I want it.

    In terms of focus, I can tell if the image will be in focus based on how the shutter sounds after I press the button. I don’t like to spend time checking the viewfinder bec the viewfinder isn’t always reliable and it can take a lot of time to zoom in, which ruins the moment (for your subject). So I take multiple shots, if there is movement, in case an image has a little bit of motion blur when I want a sharp image. Hope that answers your questions!

  • Diginz

    I have just had a quick read of this article, and having only had my DSLR now for 18 months, am still learning… and practising! But one thing I would like your comment on, doing a Photoshop course here in NZ last year, our tutor made quite a good point – “the people who are building and developing these fantastic DSLR cameras are spending millions and millions of dollars perfecting the techniques of all parts of the camera, and most of the time it would be safer to leave the camera on AUTO to leave it to use all that technology to get the best picture!’ I have taken mine off auto, and have even done my first wedding with great results (in my eyes), but will resort to AUTO to take that option as well, in case I miss something on manual. Thoughts please!

  • Laura

    I finally ‘got’ how the triangle worked recently, it all fell together in my brain. However, if I had had this tutorial when I first began learning I would have understood two years ago! I will share this with friends who are still struggling. Thank you!

  • Annie Tao Photography

    Laura, I can’t tell you how happy I am to read your comment! I love that you found my article helpful and wished you had read it sooner! I wish I had read something like this when I first started out too because I had to learn it all through trial and error on my own. 🙂 All we can do is pass on this tutorial and hope that it’ll help others.

  • Annie Tao Photography

    There are times you may want to shoot in Auto, but if you are in tricky lighting (like if there is light BEHIND your subject), you really need to have more control over your camera settings. Or, if you want to make more creative images, you need to handle the settings yourself. It just gives you more creative control. I do agree that DSLRs today are pretty darn incredible, but your camera doesn’t know how to be creative like you do! 🙂

  • jumara

    Thank you for your reply and for being so generous with your time and info. Regards jumara

    Subject: Re: New comment posted on Understand Exposure in Under 10 Minutes

  • jumara

    ok here was my problem and heavy on the was.i couldn’t understand how a picture would be in focus in manual mode.my friend told me to shoot with af on for fast moving pictures and focus the camera lens manually for portraits and more or less stills.also if I set the camera iso and shutter speed the camera will choose the av .I hope this is right because now I think I have it.

  • Dilan.Leelarathna

    Really useful & nice post. It was very easy to understand. Thank you!

  • Manoj Hukeri

    nice way to explain.. good work.

  • watercolorjen

    Great explanation~thanks!

  • FolaFayo

    Nicely explained Annie, I like the moonglasses bit on the ISO too. It came at the right time for me…shooting less of Auto

  • simirani

    This is really useful.. Thank you for the tips 🙂

  • Tony Wu

    Excellent article Annie! One point I like to express is how we tend to use large and
    small aperture and refer to them as large f-stop numbers or small f- stop
    numbers then give an example as: “A small aperture (a large f-stop or f-number,
    like f/22) and A large aperture (a small f-stop or f-number, like
    f/1.4)” However, in math, f over 22 (f/22) is really a smaller
    number and f over 1.4 is (f/1.4)really a larger number. (f being the focal
    length of the lens, so for instance in a 50mm lens, f/22 is 50mm/22 which is
    2.27 where as f/1.4 is 50mm/1.4 which equals 35.1, a larger number). We should rather use “a small f stop or f number like 1.4” (without the “f/” in front of the 1.4 number).
    My beginning photo class students gets really confused when they came across terms like use a “small or large aperture” and they always ask, are they talking about the lens opening or the number in the digital camera which seems to be oppose each other. We established that in class, we just say a small lens opening of f 22 or a large lens opening of f 2.8. Does all this make sense to anyone or is it just me?

    On another matter regarding Depth of Field and Aperture numbers, I give my
    photo students a memory aid: Imagine a yard stick, from a near distance, f/1.4
    gives you (in the range of) 1.4 inches of apparent sharpness and f/22 gives you
    (in the range of) 22 inches of apparent sharpness. (Of course this may only be
    literally true in very few instances but as a memory aid, has been very
    successful with my students.) This memory aid will allow the students to quickly
    remember that setting the f-stops in the direction toward f/1.4 give them
    progressively narrower DOF and setting the f-stops the direction of f/22 gives them
    progressively wider DOF. Hope your readers will help this memory aid helpful.

  • Annie Tao Photography

    Wonderful additional information, Tony!

  • Annie Tao Photography

    I’m glad it was helpful!

  • Annie Tao Photography

    You are very welcome!

  • Annie Tao Photography

    Glad you found it useful!

  • Rick

    A good write! Except that the “shutter speed = how long you open your eyes” is not accurate. Our brain refreshes what we see once every few milliseconds regardless of how long we keep our eyes open. So, effectively, our eyes have a “fixed” shutter speed. (That is why you can create a motion-like scene with frames of photos, if you can beat that refresh rate of our brain.) We don’t gain in exposure by keeping our eyes open longer the way we gain in exposure by keeping the shutter speed longer. It doesn’t help a bit to see the stars by keeping your eyes open for 30 seconds, although a 30-second exposure with a camera will capture a hell of a lot more stars than a 1/100 second exposure.

    I commend your approach, but your exposition will confuse a lot of newbies, and even experienced photographers.

  • Annie Tao Photography

    Hi Rick,

    Thanks for taking the time to comment! I know it’s not a perfect analogy, but when you don’t understand how the 3 components work together, this gives a BASIC idea. I think for more advanced photographers, like you, it is obvious the analogy has flaws. Good thing is, I’m pretty sure most people know when their physical eyes are open, their brain ‘refreshes’ what it sees. 😉

    Happy shooting, Rick!


  • Sarahg

    Omg! I shouldve read this before reading all the other complicated stuff! This PERFECT!

  • Annie Tao Photography

    YAY! That’s terrific!

  • Annie Tao Photography

    Thanks so much, Manoj!

  • Annie Tao Photography

    Sarah, I’m glad this was helpful! 🙂 I wish I had someone explain the exposure triangle to me in a simple way when I started in Photography too!

  • Raghavan

    Annie Tao – You are a MAGICIAN. I am a beginner, and always remained confused about the Aperture – the way it is numbered and its relationship with Shutter speed… One read of your article, has explained this ever so lucidly, which is difficult to confuse…

  • Annie Tao Photography

    YAY! So glad you enjoyed my article, Raghavan!

  • vijesh avijas


  • Dyandra

    Best explanation I have ever seen or heard. It took me months to try and get my head around these concepts.

  • Michael Shake

    Fill That Bucket!

    My favorite analogy for exposure is filling a bucket with water. A bucket, is of fixed size and needs a certain amount of water to fill it, just like the sensor in your camera. So the “camera sensor” is analogous to the bucket and the “light” is analogous to the water. To fill a bucket, you can pour a small stream of water for a long time or a large stream of water for a short time. Either way, you end up with the same amount of water in the bucket.

    The size and volume of the stream of the water is analogous to the f/stop. The f/stop is the size of the aperture opening that lets the light in through the lens. Bigger opening like f/2.8 lets in a lot of light pass through the lens while f/22 is a small opening and lets in much less light.

    The length of time you pour the water is analogous to the “shutter speed”. In the bucket example a large stream or volume of water will require less time to fill the bucket. A small stream or volume of water will require more time to fill the same bucket. For photography a large aperture setting like f/2.8 requires less time, faster shutter speed, for the light to fill the sensor and a smaller aperture like f/22 requires more time, slower shutter speed, to fill the sensor with light.

    The size of the bucket is analogous to the “ISO”. A smaller bucket fills up faster then a big bucket. In photography you can make the sensor more or less sensitive to light, a low ISO setting of 100 will take more time to fill the sensor with light while a high ISO setting of 2000 will take less time to fill the sensor with light. Think of a low ISO of being the big bucket and having more water or light information in it while a small bucket has less water and less light information in it. The quality of a photo is better if shot at ISO 100 then ISO 2000.

    Broadly speaking, from the bucket’s point of view, it doesn’t matter which combination of stream size and length of time you choose as long as the right amount of water ends up coming in to the bucket. Photography is the same, within limits, your camera is indifferent as to the combination of time and amount of light as long as the right amount of light eventually arrives on the sensor.

  • Raewyn

    This was so helpful. Obviously I was just using “no brain” when trying to learn this stuff previously. Thank you for the fantastic and quick to learn lesson.

  • Choo Chiaw Ting

    I may use these settings,, which may not agree by you 😉

    1) Quiz 1

    Freezing Approach:

    a) Walking away from the lens, making the movement less drasmatic. But kids awalys move fast. According to https://digital-photography-school.com/shutter-speed-chart/, 1/250s is not sufficient, 1/320s is a better shutter speed for moving kids. So i will open my eyes in 1/320s.

    b) Moving away making the distance between lens and subject greater. To separate her/him with background at great distance, I need to open my eyes wider, and wider as she/he goes further

    c) The thickness of moonglasses, depends on the brightness of the situation. Under the midday, i may need to choose the thickest moonglasses. If it happens to be night time, then i will properly even “Take off” themoonglasses lol.

    Panning approach using shutter priority

    according to https://digital-photography-school.com/shutter-speed-chart/

    Shutter 1/15s,
    use Shutter priority
    Aperture: As narrow as possible lets the camera decides for you
    ISO: using the highest tolerable ISO(e.g. D4 to ISO 6400; D800 to ISO 1600 etc, D5100 to ISO 1000)

    2) Quiz 2

    Change to shutter speed priority
    Increase Shutter speed to 1/320s

    Change the ISO to highest tolerable ISO (e.g. D4 to ISO 6400; D800 to ISO 1600 etc, D5100 to ISO 1000)

    Depends on the shutter speed / ISO, use the narrowest aperture possible (perhaps f/2.2 instead of f/1.2, let the camera select for you), well depending on the focal length too 😉

  • Rakesh Sayam

    Really nice explanation

    ISO – Moon Glasses (adds light)
    Shutter – How Long u open eyer
    Aperture – what extent u open your eyes …
    My answer would be
    1. In cat’s scenario ISO ++ Shutter — will give the same result
    2. Increase ISO

  • marlo jolbitado

    amazing … Sharing this with my friends … 🙂

  • Sheree Zielke

    I tell my students that the sensor is like a sponge, a sponge that absorbs light, and that the ISO controls the sponginess of the sensor…the higher the ISO number, the spongier the sensor, the more light it can absorb. So, when there is lots of light, the sensor does not need to be as spongy and the ISO setting can be kept to a lower number.

  • Heather

    As a “newbie” to
    understanding how to use a DSLR, and not just using the automatic feature :), that is the simplest explanation I have read…so easy to understand.. thankyou, now to put it into practice.

  • Annie Tao Photography

    I am so glad my article helped you! 🙂

  • Annie Tao Photography

    That is such great news! Thanks for your comment, Heather. I’m glad my article was helpful!

  • Annie Tao Photography

    Share, share away!

  • Well said. This was a great refresher for me. Thank you!

  • Tiffany

    It’s people like you who makes the world go around! I have always loved photography since I was young, but I am just now getting into the “books” and technicality of it.Thanks for helping me to understand what I’ve been researching for days in just 10 minutes. In some ways, we are all like a child when it comes to learning something new–because it’s…new and different. Simplicity is key and your explanation is something both right- and left-brainers can easily understand. I can’t wait to put all of your photography tips into practice.

  • Annie Tao Photography

    Yes, DPS is awesome!

  • Annie Tao Photography

    Tiffany, you are too kind! Thank you for your thoughtful comment. I am so glad to hear that my article was helpful. I am self-taught in the field of Photography and, like you, it took awhile to understand exposure. So I wanted to explain this the way I wish it was explained to me years ago! 🙂

  • Annie Tao Photography

    Refreshers are good. 🙂

  • Super article. Loving moonglasses!!

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