02. Understanding exposure

Getting the balance of light right requires an understanding of exposure, or the “brightness” level of your picture. Your cameras light meter can help you do this but this isn’t the only way to do it.

How can you make these decisions for yourself? In this chapter find out how and why exposure matters as Karl demonstrates how you can control the exposure. He shoots a number of portraits with different shutter speeds and also explains the relationship between aperture and shutter speeds and how you can adjust these to get the best results.

In this photography class we cover the following:

  • What is exposure
  • How to control exposure
  • Aperture: How to control exposure with aperture
  • Shutter speed: How to control exposure with shutter speed
  • ISO: How to control exposure with ISO
  • The relationship between aperture, shutter speed and ISO

To learn more about some of the concepts discussed in this class, take a look at our Photography Quick Start Guide.

If you have any questions about this class, please post them in the comments section below.

NOTE: This course is available with subtitles.


  1. Karl, can I please ask you what’s the best practical video camera you would recommend for behind the scene shooting …?

    1. Hi Tony, we use the Sony Rx100 mk3 but there are new models out since. I like this camera because it has great video quality and is quick and easy to get out the bag and has a flip up screen for selfie behind the scenes video too.

  2. Karl hi where is the new course you was saying about it I am still new so please let me know how to start thx sr I want to learn from you as much as I can thx teacher.

    1. Hi Gabriel, our newest course is Light Source, you can find it under the portrait tab at the top, if its the latest live show Karl was talking about, you can find that by clicking the live button at the top of the site and then scroll down to the archived shows, hope this helps

  3. You are brilliant , i have seen 100ds of hours of toutourals on youtube and this is the clearest of the bacics. thanks Karl.

  4. Karl…..you just clear that big mystery on the f-stops and speed for me in 15mins than many many hours on youtube and bloggers. I am SO GLAD I signed up!
    You are a genius!


  5. Hi Karl, at one point in the video I see you are using “AI servo mode” on the older DSLR.
    Would that be your preferred choice over “One Shot AF” in this kind of portrait situation?

    1. Hi Dirk, I actually mostly use manual focus as that was what I was use to from the ‘old’ days before digital! Then I’d say I use one shot AF and only servo if the subject is moving towards or away at a manageable speed.

      1. At 0.24 the Tilting movement, what is it for?? Is it focusing center to the eye with “One Shot AF” then move back to the center of the image and take the shot?

        1. Hi Michael, yes although on many modern cameras you can select a focus point off to one side instead. Some now I think even have eye recognition to know where you are looking.

    1. Hi Edward you can see the settings for each shot on the back of the camera and in the simulated viewfinder for each shot.

  6. You mention using the in-camera meter as a way to get the exposure right. I often find, though, that taking a picture at the zero point ends up in an overexposure (i.e., with lots of blown highlights), so I’ve been taking my shots slightly “underexposed” (according to the camera), but which have less overblown highlights. Would be interested in your comments on this.

    1. Hi David, I only ever use the camera’s light-meter to get it in the ballpark, after that it’s manual decisions all the way by looking at the preview image and the histogram. Cheers Karl.

  7. Karl, I have been a professional photographer for over 20yrs and this was the best translation of exposure using film camera vs. digital regarding exposure I have every seen! Very well explained! Thank you!

  8. Hi Karl, I am kind of brand new in photography, even I have been passionate about it all my life. My question is, how do you know when is the right exposure, is there any way besides having a light meter, does the histogram will help? cause if you use a 1/125 won’t make a big difference but how you will know 1/100 is the right one? hope I explain myself. Thanks

    1. its more about what you are trying to achieve rather than a set exposure, Karl always just takes a shot, looks at it and then adjusts the exposure to what he wants it to be

    2. Hi Luz, the look and feel of the picture has a lot do with it. Does it look how you wanted it too? If not why not? What is causing it not to look like that? The second thing is the Historgram that can give you a lot of factual information based on the expected content of the image, you will find more information on Histograms in another module. Cheers Karl.

  9. Great video-I cant help thinking that in this tutorial the image that you state is the ‘correct’ exposure to my eyes looks a little bright, whereas the image taken at 1/200 looks a little more moody and natural. What are you deeming a correct exposure here? What you go for as a photographer, the light meter reading or a histogram reading?
    Thanks, Mike

    1. Hi Michael, if i’m not shooting tethered (which is not often in the studio) then i’d look at the histogram in combination with the image on screen, that would allow me to interpret the histogram in correlation with the image. When I shoot tethered then I’m linked to a properly calibrated monitor and can trust what I’m seeing as well as take measurements of RGB values from key points on the image.

  10. Hi Karl, Brand new subscriber to your site and liking what I’ve found so far. I am going to work through all the videos, but is there one that specifically addresses effective use of the histogram to judge exposure? Just getting started so forgive me if the questions seems impatient…:). Regards, RJ

  11. Hey Karl i just bought a nikon D3100 so i’m starting.
    I have one question, when i’m shooting can I trust the light-meter?
    Thanks, Cheers from Paris !

    1. Hi Filipe, you trust it to get your test shots and get you in the ball park and then you look at the results on the screen in combination with the histogram and then make a decision from there in manual mode on where you would like the picture to go. You will learn more on this as you progress through our courses.

    1. Hi Brian, different lenses have different maximum apertures. As you progress through this course you will realise there are two other ways to compensate for the exposure other than the aperture; shutter speed and ISO. Give me a shout again at the end of this course if you still have any questions. Regards Karl.

    1. Hi Marilyn, thank you. Of course if you have any questions just leave them in the comments section below any module.

    1. Hi Joel, the simple answer is when it looks right. A slightly better answer would be when your highlight detail is within reproducible limits and only the very very darkest area of the image is black but the areas of shadow are still perceivable and yet with all this does it still look right.

    1. Hi Chethan, it’s calculated in general terms by the focal length of the lens divide by the diameter of the opening aperture physical size. Essentially though f8 or f11 on one lens should be a similar exposure value to f8 or f11 on another lens.


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