top of page

By Eugene Struthers



Two of the most commonly used light meters the Sekonic L-308s & Sekonic L358. Have been used in this tutorial for demonstration purpose only. There are other light meters available which work just as well.


The Sekonic meters used in this tutorial are being used only for demonstration purpose. 

Why should you use a Light Meter?


When you shoot in a studio there is more light and reflections then is actually needed, it can then be tricky to get the correct exposure. The professionals don't get stressed out because they use a light meter. In almost all circumstances, they will use a handheld light meter. The camera's built-in meter just doesn't have the necessary capabilities to function correctly in a studio or outdoor lighting condition. So you want to give it a helping hand, as it will make your job easier in the long run. Especially if you have a mix of different light sources & strengths. In situations where you may need to mix ambient lighting with strobes or flashes. (We cover this topic in the "Advanced level photography course")


Every photographer wants a device that will tell you exactly how to set your exposure, it will allow you more time to chat with the topless gorgeous model. Perhaps find out if she has a twin sister.


The light meters that are available today, are simple and easy to use. They make our lives as photographers whether amateur or professional much more easier. Yes, you can take a photo, upload it onto your computer and spend the rest of the day using photoshop to correct and fix the exposure. Makes corrections harder, and time-consuming. It would be more logical to take a picture at the right exposure the first time with a handheld light meter. I use a Sekonic L-358 Flash Master Light Meter. It takes the stress out of a studio shoot. But I also own a Sekonic Flashmate L-308S, as a backup.


This tutorial is a basic understanding of how to use a light meter. An in-depth understanding of Light meters is covered again in the "Advanced course".  

Download the L-308S manual here: Click here
Power button
Mode button
Liquid crystal screen (LCD)
ISO button
Synchro cable terminal
Up button
Down button
Lumisphere (Light Receptor)
Download the L-358 manual here: Click here
Continuous light like natural light (sunlight) as well as tungsten lamps and fluorescent
lamps are measured in Ambient Light Mode.
Measurements in this mode are made in Shutter Speed Priority Mode, Aperture Priority
Mode and EV Mode. Press MODE Button to select the Ambient Mode.
The incident light method measures and calculates the intensity of light fall directly on to your subject. The lumidisc needs to cover the photo-optic lens sensor. Point the light meter directly back towards the camera.
The reflected light method, measure and calculates the intensity of light being reflected off of your subject. To take a light meter reading, hold the meter in front of the camera pointing back towards your subject. Do not cover the photo-optic lens sensor with the lumidisc. The reflected light method takes a calculated measurement of the luminance of light reflected off a scene or subject.
Cord flash

How do you use a light meter


There are a few simple steps you need to follow before using a light meter. First I would recommend understanding what an ISO is. And determine what ISO sensitivity setting would be suitable for your particular lighting situation. This will give you a board understanding about how your camera interprets your commands imposed upon it, in relation to the end result you would like it to achieve for a certain lighting condition.


Secondly, you will need to determine a required ISO setting. Enter the ISO given from the camera into the light meter. Let's say you want to work with an ISO of 100 as the light conditions are fairly good. As it is an exact match for the ISO you have dialled into your camera. You enter this amount into your light meter.


Next, you extend the retractable white plastic round dome lumisphere in the front out, pointing it back towards your camera on its tripod. If you are working with a model, ask her to hold the light meter below her chin, even better ask the model to push the trigger button on the side of the light meter and you manually trigger the strobes with a trigger while you take a test shot of the flash. The light meter will flash symbol will flash for a few seconds on the LCD screen. To allow time for it to take and capture a reading. Depending on the light meter mode measuring set. The light meter then will then instantaneously take a reading given off from the flash/strobe. This reading on the LCD screen of the light meter will then give you the correct aperture and shutter speed required to take a crystal clear exposure. Then while the model re-adjusts herself, you step back to your camera, dial in the results from the light meter in manual mode - and "Hells Bells" perfect exposure. After a few practices, you will develop a thorough understanding and come to realise that if you move or introduce more lighting another flash/strobe test with the light meter will be required. Changing the shutter speed and aperture as required to accommodate the slight difference in light intensity.

What is the main function of the Lumisphere?
What are the measuring modes
Sun symbol (Ambient mode): Used when taking an ambient/ non strobe flash readings.
Lightening bolt symbol (Auto-Reset Cordless Flash): The symbol will flash for a few seconds to allow you to trigger the strobe manually so that it can take a light reading. 
Lightening bolt symbol + C (Cord Flash): Pressing the measurement button on the side of the light meter sends a signal via a cable to the strobe to fire, so that the light meter sensor can take a reading.  
Lighting bolt symbol + T (Wireless flash radio triggering mode): Similar to the above process, but instead of a cable the strobe/flash is triggered and fired by a wireless signal sent via the light meter directly.
18% Grey card

How to take a grey card 18% meter reading


The process

1) Place an 18% grey card below the chin of your model, ask her to hold it for you.

2) Put your digital DSLR on an auto mode, either "Aperture priority", "Program mode" or "Shutter priority".

3) Fill the frame of your viewfinder with the grey card.

4) Half depress the shutter release button on your camera to verify the exposure settings. Whilst doing so note down the settings from within the viewfinder during the exposure focus.

5) Change your camera to "Manual exposure mode" and input these value exposure settings.

6) Important to be beware This whole process needs to be done fairly quickly if you are outdoors, as your lighting conditions will be constantly changing.

ISO setting: First set your ISO to match the ISO on your digital camera (ASA speed), Film. This is done by pressing the ISO 1 button and then turning the jog wheel on the side of the Sekonic L358. Once the wheel is turned you will see the ISO setting indicator change in the righthand corner of your LCD screen. Make it land on the same setting as the ISO of your camera.


Metering for available light: Put your camera on Manual mode, this will allow you to set the aperture and shutter speed making an independent change. If you left it on Auto mode, the camera setting will change according to the amount of light available in a given scene. This is difficult and can fool the camera to not see and acquire information which you need it to store and have in the image. This can be different contrasts in color, bright dark backgrounds, with a model wearing black clothing etc. And your camera may struggle to acquire the necessary information in order to take a correct exposure. In the manual mode, you manipulate the camera's settings and the commands are constant. As a photographer, you want to pick an aperture to use depending on the scene you are photographing and then measure how much light there is available for the given aperture. At this point, you may ask the model to just wear red lipstick for her next photo shoot. Just red lipstick and nothing else. I find that this helps with concentration. So while the model slips out of her bikini, you go into your camera bag and get out your handheld light meter. You pick the required aperture and then the camera will display the shutter speed to use with that aperture. This method is called using the Light Meter in "Aperture Priority Mode".


Now for the technical stuff


How to put the Sekonic L358 meter in "Available light" Aperture Priority. 


First, press the Mode button while turning the jog wheel. Keep turning the wheel until you see the "Sun symbol" (Top lefthand corner) encased in a box. Once it is placed in a box, this means that you have placed the meter setting to available light "Ambient" mode. As you turn the jog wheel while pressing the mode button, you will notice that the sun setting has two sub settings. These will be one in which "T" (Shutter speed) is displayed within a box and another where the "F" (Aperture) is also displayed in another box. While pressing the mode button with the sun symbol in a box, turn the jog wheel so that it lands on the "F". This indicates that you would like to have the meter on aperture priority mode. So basically you can dial in the aperture and the meter will suggest an appropriate shutter speed reading for the light you have set it too. Fairly simple.


Just remember these simple settings:-


1) Sun symbol in a box (in the upper lefthand corner).

2) Place the "F" symbol in a box as well.

3) Turn the jog wheel until you get the required aperture setting on the display.

4) Press the measuring meter button to take an ambient light reading.

5) The light meter will display the shutter speed. 

6) Take these light metering settings and input them into your camera in manual mode.

7) Take picture of bored naked or topless model with great personalities. 



Go outside into the open sunlight. Turn the jog wheel on your Sekonic L358 until it reaches F11. Retract the white dome lumisphere out and point it towards your light source, in this case, it will be the sun. Keep a steady hand and then press the trigger activation button on the side. The display screen will now indicate the correct shutter speed to use. Now input these two "Aperture" & "Shutter speed" into your camera. You are now ready to capture your first image. But please be aware of the available weather, as conditions can change very quickly and you may just need to take a new reading.


How to put the Sekonic L358 meter in "Available light" Shutter Priority Mode.


This mode is used mostly for circumstances when you don't mind what aperture the meter is automatically set too. Without stating the obvious this would be ideal for sports and action photography. Objects which are projected, people moving at high speeds. You want to shot at say 1/500 and let the meter advise you what aperture to set your camera to. This is using the meter in Shutter priority mode.



This is how you do it.


Similar to the "F" setting as discussed above. We now press the Mode button, while turning the jog wheel until the sun symbol (Upper left-hand corner) is encased within a box. Now keep turning the jog wheel so that the box lands on the "T". This indicates that you would like to have the meter on shutter priority mode. By simply turning the jog wheel until you see the required shutter speed. Now aim your white dome lumisphere at the light source keep a steady hand and then press the trigger activation button on the side. The display screen will now indicate the correct aperture setting to use.So basically you can dial in the shutter speed and the meter will suggest an appropriate aperture reading for the light you have set it too.


Metering for Strobes


To make this simple and inexpensive, use a sync cord with one end attached to the flash/strobe and the other attached to the meter. Set your camera to 1/60 Shutter speed. Leave it on this for now. Most cameras will sync with strobes at this shutter speed.


Now for the technical stuff


How to put the Sekonic L358 in Flash mode


Press the Mode button, while turning the jog wheel until the box is around the lightning bolt symbol with the letter "C" figure. This letter C just means that the meter will trigger fire your strobe when a sync cord is attached to the meter and the strobe. The lightning bolt with the letter "T" is used for a wireless trigger and the lightning bolt on its own is used when you trigger the strobe manually without a sync cord. More on these two later. Lets first understand the concept of what we want to achieve before going too far ahead into the technical stuff which may cause confusion at this stage. Okay; back to the lightning bolt with the letter "C" figure. Once you have this you will have the meter in flash mode. Release the mode button and now input the sync speed. This is done by turning the jog wheel until the speed is displayed on the lefthand side of the LCD. It will appear on your display screen as 60 and not as a fraction 1/60.


Ready for a Test:-


Position your meter within the required shooting area. Retract the white lumisphere dome out. Pointing it out towards your main strobe. Press the trigger activation button on the side of the meter. Your strobe light should now fire. The meter will instantaneously pick up this flash reading and recommend a relevant aperture to use on the display screen. So now you have the ISO:-100, Shutter speed:-1/60, and aperture taken from the Meter LCD display. Let's say Aperture:-F11. You are now looking and feeling like a professional.


But before I forget, you will want to apply one exception. You will have to remove the sync cord from the meter and attach it to your camera's sync terminal. So that a connection is made between the strobe and your camera. It is now time for you to call the model onto the studio set.


Simple and easy, isn't it?. You are ready. Your only concern now is where to have lunch. Okay; but you get the picture. Excuse the pun. No use complicating the situation if we now have the technology to make it easier for us and we can deliver excellent results.


Yes I know we can use standard ISO, Shutter speed & Aperture settings when in a studio. But this can become more complicated once we introduce a second or third lighting source. Each at different power light strengths and ratios. This will just be too much information for your camera to handle.


You will have probably heard that some photographers never use a light meter because they rely on their histogram to give them an accurate on camera LCD screen reading using the shadows, highlights, and mid tones to influence their light setup.


But in order to grasp the fundamental principals of how a light meter works. We have to know the basics. 


I cover why the light meter reading given by the histogram might not be your safest option in the Advanced course.  


Uncomplicate your skills as a photographer, by purchasing a reliable "Light Meter".



When the lumisphere "lumidisc" is slide to the left and up. It clicks into position to take an incident light measurement reading.
When the lumisphere "lumidisc" is slide to the right and down. It clicks into position to take a reflected light measurement reading.
When the lumisphere "lumidisc" is slide to the right and down and an extra lumidisc is insert over the slot over the light receptor lens together. It clicks into position to take a measurement reading of flat subjects or lighting contrast with precision.

When the lumisphere is raised and aimed directly at the camera, it is used to measure the amount of light falling on a person or subject.

When the lumisphere is retracted, it is used to measure flat diffused lighting. In this position it is mainly used to measure the amount of light falling on manuscripts, paintings or anything of a falt nature.


It is also used to determine the illumination levels or brightness differences between two or more light sources. This will be covered in more detail in the "Advanced Photography course".  

Exposure Value  (EV mode)
EV (Exposure Value) provides an easy way to observe differences in light falling on a
scene or subject when illuminated by a continuous light source. An increase of 1EV
indicates a 100% increase or doubling of the light. Conversely, a decrease of 1EV
indicates a decrease of 50% or halving of the light.

●● The relationship between aperture value (AV), shutter speed value (TV = Time Value)
and EV is EV = AV + TV. From this relationship formula, the number of ways that the
aperture and shutter speed can be combined against a certain constant EV can be

What is Exposure Value (EV)

When we use a light meter, we have the option of enabling it to give us a reading which combines both the "Aperture and Shutter speed" into one exposure value according to our camera's sensitivity ISO. So instead of seeing both the "Aperture and Shutter speed" on the LCD screen, we will only see one number which relates to a combination of "Aperture and Shutter speed" settings. 



Why do we have this number? 

Our digital camera and light meters, see light exposure at a given sensitivity as an "Exposure value". This is then broken done into two combination settings of "Aperture and Shutter speed". Which in turn makes it more user-friendly for us photographers to compute and dial into out camera settings. The Exposure value is ideal if you are working in lighting conditions where you know there is going to be a greater difference in tone and contrast across the entire image. You can then use the Exposure Value to be more precise and capture these differences in Luminance in your scene. This was a technique widely used by Ansel Adams to spot meter a particular scene to verify the "Exposure value". Click here: Zone system. I cover spot metering in the "Advanced photography course". 



How do we read an Exposure Value?

The exposure value can be calculated using a light meter. Simply select the "EV" on the light meter at a desired ISO sensitivity setting. Then capture a reading off of a scene you what to photograph. (please refer to the graph below) In this example, our light meter gave us a reading of EV 14 for an ISO 100. In order to input this EV setting into our camera, we will require the "Aperture and Shutter speed" settings. So next we check the "Exposure Value" chart to verify which "Aperture and Shutter speed" would best suit our own particular photographic conditions. The Exposure Value chart has given us a wide selection of alternative "Aperture and Shutter speed" settings to use. We could use EV 14 at f/16 at 1/60 or EV 14 at f/2 at 1/4000 setting. 

































































It is a sunny day and you are trying to create some fine art nude images of your model in an old dilapidated Victorian mental asylum. The light conditions are really mixed, and the differences in tone and contrast are very noticeable.  


So you decide to use the "Exposure Value" setting option mode on your light meter. After taking a reading the LCD display on the light meter displays a reading of EV 14 at ISO 6400. Unsure what combinations are available for this Exposure Value setting, you pull out your portable mini "Exposure Value chart". To verify what available "Aperture to Shutter speed" combinations are available at a particular light sensitivity ISO setting. Scrolling across the list on the chart. You are then able to verify. That at EV 14, ISO 6400 you will be looking a really fast shutter of 1/3000 with an Aperture of f/5.6. 


It's a sunny day, these settings won't be suitable. Plus the ISO is way to high. So you decide to reduce the ISO to 200 and check what Aperture you would get if you were to shoot your model at your flashes sync speed (covered in the advanced course) of 1/250 sec. Scrolling up the Exposure Value Chart, it recommends you use f/11. You now know that you have all three camera modes, so you dial the Aperture + Shutter speed + ISO combination into your camera to obtain the correct exposure.  The image turns out perfect as you have followed the Exposure Value process.


Sometimes the "old school" methods are your best option.


In my experience, a lot of new photographers find reading the Exposure Value confusing. Mainly because they may not always be using an ISO 100 setting and they don't feel it necessary to have an "Exposure Value Chart".


To simplify this process in 2018: I would recommend using an "Exposure Value" chart or a mobile phone application such as these and others available to download to calculate the correct exposure "Aperture and Shutter speed" combination for the ISO you will be using.  



                                           1) Exposure calculator (a): Click here                               2) Exposure calculator (b): Click here


This is a basic understanding of how to use a light meter. I cover this topic again in more detail in the Advanced level course,  when we work with mixed lighting conditions, strobes, and flashes. 





         See you all

next month

bottom of page