Measuring Light and Achieving the Correct Exposure

Get the measure of light with this simple class.

How do you measure the power of the light from your studio lighting to ensure perfect results? Do you apply visual, theoretical, histogram or light meter readings to achieve the best results?

Karl discusses the best ways to measure light and achieve the desired exposure as well as the limitations of the above methods and why it’s important to truly understand light if you want complete creative control.

In this class:

  • Different methods for measuring light
  • Light meters — what use are they in digital photography?
  • Assessing exposure visually
  • Combining aperture and shutter speed to achieve desired exposure
  • Reading histograms
  • Correctly exposing for different textures

Questions? Please post them below.


  1. Hello
    How are you?
    With respect I disagree very strongly. Surprised by your wild comments about light meter users.
    Competence and experience determines where to place the exposure. Not blindly follow what a meter tells you.
    Any competent photographer properly trained knows that a light meter must always be used with a 18% grey card. No excuses. No exceptions. This gives you proper exposure for Zone 5.
    With film (b&w or colour) we always work between zone 2 (-3 strops) and zone 8 (+3 stops) to retain details in shadows and highlights.
    Gossen Lunasix F handheld meter has the zone scale clearly marked. Digi meters like you are using dont.
    Competence and experience determines where to place the exposure. Some may argue artistic interpretation may play a role in “high key” and “low key” photographs.

    1. Hi I’m confused as to your comment as my argument in this class was that competence and experience was what determines where to place the correct exposure? Also this class was aimed at those taking incident flash readings not reflected off a grey card?

  2. John

    Hi Karl. Loving your video lessons! I came across an old Sekonic L-28c2 light meter at a thrift shop. Is this something that I can still use for my photgraphy or do you recommend a newer, digital one? I’m having a hard time finding a video on how to use this particular model for still photography.

    Many Thanks!

    1. Hi John, for the way I work I wouldn’t even worry about it. Sekonic are a good brand and as long as it’s still on point at the correct exposure (check it compared to the result) then I’m sure it will do all you need.

      1. John

        Thanks Karl. I actually just found your video on not using light meters hehe. I’ve been learning your methods thus far and while I may use this just to learn how to use them, I’ll probably stick to your setup methods with being tethered and use the meter for getting a baseline in filmmaking.

        Thanks so much for all you do!

        1. Cheers, John. I don’t think there is anything wrong with using a lightmeter in general, especially if shooting on film, it’s just that the way we shoot these days and the other tools we have at our disposal mean that there are alternatives that I think help the creative process of decision making based on what we see rather than what we are told it should be. All the best Karl.

  3. I want to start by saying your course is excellent. I started loving sports and land scape photography but your style and teaching has gotten me really excited about portrait photography. I may know the answer but i wanted your opinion on aperture setting. Do you determine what F stop you are going to use by how you want the image to look, or is there a sweet spot you like to use personally? I know you set the F stop and shutter speed and adjust the light to that, just curious on how you go about determining what F stop you will use. Thank you

    1. Hi, thank you. Yes I determine the aperture I’m going to use based on the DOF I require for the creative look. For example in softer portraiture this will be shallower DOF but in fashion/beauty head shots it will be greater DOF, so it is always based on that creative decision and then I match the lighting to suit.

  4. Hi Karl, loving your work and your course. However, like CharClarPhoto said, I am going to have to disagree with you on this chapter. I have to agree with all that he said, and I am adding that you measured the reflected light, not the incident light (you should had pointed the lightmeter to the light, not to the camera) and if you want to underexpose the subject you could do it easealy and based on the right exposition.
    And yes we can use the histogram and our eye, of course, but I have to mention the usefulness of the lightmeter about the ratios of light.
    That said, I am happy to learn with you and your courses. (Sorry for my english).

    1. I have to agree with Barrento, used correctly the light meter can speed up your workflow & achieve consistent reliable results (under studio conditions). It’s how we were taught in BA Photography, as I say to achieve repeatable consistent results. It’s how many of the Universities/colleges teach getting studio lighting ratios correct.

      As you well know clients looking at your work often want similar/ identical results to portfolio work. And you can speedily achieve this taking extensive notes of your lighting set ups & ratios. To achieve consistent results

      Also inbuilt camera light meters are not as accurate, every single camera/model can & will give different results. However properly calibrated light meter will give accurate results. Yes we often have to compensate slightly, but that’s down to the cameras not the light meters.

      Like Barrento I do enjoy your courses but I have to disagree with your theory & the way you used the light meter

  5. Vic Peralta

    You suggest using a Color Checker in lieu of using a light meter. I have a X-rite Color Checker. If I am careful with the color checker (don’t touch the color pads, I store it in a bookcase and so on.) My question is do these color checker expire or loose potency?

    1. Hi, the Passport version is good because it comes in a protective case that keeps it in the dark, but if you look after a normal X-rite card it would last you 10 years.


    Hello Karl,

    My question does this also apply to speedlites? I just purchase a speed lite with a trigger …should I get a strobe lighting instead?

    1. Hi, my understanding is that strobe light and speedlite are the same thing? A small unit that bursts out a brief blast of flash? I believe in the USA they use either term? A studio flash as I was using in this class is essentially a bigger more powerful version of the same thing. A continuous light such as LED is different as it doesn’t have the burst of flash but even with those I’d use the same technique for measuring and assessing light.

  7. Hi Karl,

    You mention shooting tethered…
    Is that subject covered in another section of the course?


  8. Hi Karl, loving your course. However, I am going to have to disagree with you on this chapter. You are so adamant about not using a light meter that you are not fully honestly representing the use of a light meter. First, the light meter I have allows me to set the aperture I want to use and then it shows me the shutter speed and/or ISO I want it to calculate ( or any combination of aperture, shutter speed and ISO that I want to select). Second, I don’t think a serious photographer is going to follow a light meter settings blindly (just like you don’t follow your in camera meter/histogram blindly when shooting weddings where the bride is in white and the groom is in black), they will add their creativity to the final setting they will use. Today’s light meters calculate ratios and other things. I think a light meter can be a fine tool for outdoor creative photography, whether it be a model/senior/environmental shoot, or doing black and white zone system shooting. We cannot always be tethered, nor can we always rely on the histogram. However, if you are only referring to “in studio” shoots, then perhaps the title of this chapter could include the “Studio” in the title or in your presentation. And to say someone does not understand light or is trying to justify their purchase, just because they use a light meter, is not true.

    That being said, I still love your courses and your expert and professional presentation of the material. Moving on to the next course, see you there.

    1. Just realize the “Overall Course Title” says “…use studio lighting”, by bad! Continue on sir!

      1. Hi CharClarPhoto, yes the information in this class was relating purely to measuring the output of studio flash lighting and where I see the fallibility in doing so compared to analysing the results visually (which is also using a light meter, just your eyes and brain instead). For me and many other professionals the ethos of good studio lighting is about creating mood and emotion through the choice of modifiers and the look and feeling of the light – this is something that doesn’t need a light meter it simply needs an artists eye. Additionally in such a studio lighting environment the aperture, the ISO and the shutter speed should already have been predetermined so the only thing left is to decide on the amount of light which can simply be turned up or down like a volume control until the desired result is achieved.

    2. AGREED!

      I have a light meter that works with aperture priority or shutter priority. It has an incident meter, flash meter, and spot meter along with the ability to store multiple ISO’s and be programed for your digital camera’s sensor…. I can obviously get the photo I need with a raw file and the ability to see if I’m clipping shadows and highlights on a modern digital camera, but I still shoot film and trusting the in camera meter isn’t an option.

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