Measuring Exposure: How to Use the Light Meter

Last lesson we visualized the exposure triangle to finally complete our discussion on photography's most important shape. We mentioned that the exposure triangle is comprised of the ISO, shutter speed, and aperture.

Finding the balance between the said elements is key to creating perfectly exposed images. However, we mentioned that finding the harmony among those elements is easier said than done but can be obtained by understanding the exposure triangle.

Although ISO, shutter speed, and aperture have their own responsibilities and ways of managing the amount of light as seen in your images, we said that they are more than that.

The ISO is critical for the evidence of grain in your photos while the shutter speed heavily affects the motion blur or sharpness of the subject. Meanwhile, the aperture is heavily involved in the manipulation of your depth of field and the radius of your focus area.

To make our way further into the study of exposure, we will know tackle an important tool in your camera. This tool is the light meter and it is very helpful in determining how you make use of the exposure triangle.

A Tool Taken for Granted

The light meter is a very helpful tool in determining the exposure of your camera even before taking the actual picture. It is a camera feature that traces its roots to the earlier days of photography where shots are limited and photographers had to be smart about each click of the trigger.

Unfortunately, due to the emergence of digital photography, people have taken the light meter for granted. In digital photography, instead of using a roll of film you are using data which means that if you do not like the image you can simply delete it.

Turning into digital, photography has since been friendly to trial and error where photographers can just snap a photo and do the adjustments accordingly.

However, that doesn’t mean that the light meter is rendered obsolete already. Much like the transition of ISO from traditional to digital, the light meter has also adapted by adding more features such as digital metering - things that we will be discussing in the future.

The Light Meter

As mentioned, the light meter helps you determine the exposure of your photo even before you take the actual picture. It does this by showing you a meter that ranges from -3 to 3 where as the value increases, so does your exposure.


As shown here, should your meter point to -3 as your value then you are about to take a really underexposed photo. On the other hand, a value of 3 indicates the total opposite which means you are looking at an overexposed image-to-be. 

Once the light meter hits zero, that simply means that your shot will have a balanced exposure. 


The light meter is often seen on the topside of the camera, usually behind the clicker. For other cameras, the light meter can be seen through the viewfinder finder or on the screen itself.

Using the Light Meter

Now that you know what the light meter is, it’s time to know how exactly do you use it. 

The answer to that question is pretty straight forward: the exposure triangle. The light meter and the exposure triangle work hand in hand to give you a perfectly exposed photo. 

If you are overexposed, let’s say at +2, then you can simply stop down (increase the value of your aperture) to make your aperture smaller thus letting in lesser light. Apart from that, you may also choose to increase your shutter speed to let in lesser amount of light. 

You might be wondering why we are not using the ISO as an adjustment, right? Well, that is because using the ISO as an adjustment in relation to the light meter can be inaccurate. 

This simply means that your ISO adjusts in large amounts whereas the light meter is all about precision. Adjust using your ISO and you may not end up reaching the zero mark. 

However, do note that sometimes your goal may not be to hit the zero mark. Depending on the situation, you may need to overexpose your photo a bit such as in the case of subjects with deeper shadows. 

Conclusion

So today we learned about the light meter - a helpful tool for determining the exposure of your photo without taking a picture. The light meter eliminates the need for trial and error which is great for film photography. 

The light meter can be seen in different parts of the camera depending on what model you are using. Interpreting the light meter is quite simple where the lower the number is, the lower your exposure is. 

To adjust in relation to the light meter, simply use your knowledge on the exposure triangle although the ISO may not be the best choice since you are looking for precision. 

Our next lesson will give us a deeper understanding of the light meter and how it has made itself useful in the digital age. For the next article, we will be discussing the different types of metering and you wouldn’t want to miss that. 


In line with that, don’t forget to keep on sharing these lessons to your peers to help their careers as well.