Questions (frequently) and their answers (simple) for you to master light and exposure in photography

The first frustrations of a budding photographer come from the photographic exposure and everything that has to do with light when you decide to leave behind the automatic mode of your camera. From dark photos to images that are too bluish, going through endless everyday problems that can be easily solved with some basic knowledge. That’s why today I bring you frequently asked questions about light and exposure in photography, with the answers that will help you take the steps you need. Everything is much simpler than it seems, you will see it right now. And if you want to delve deeper into lighting in photography, don’t miss this very complete guide that you have at your disposal on the blog.

What is the exposure triangle?

There are three parameters related to light exposure in photography that are crucial to achieving a correct image. These are aperture, shutter speed and ISO. These three parameters combine with each other to achieve exactly the type of photography you want. Once you control this triangle, there will be no photo that can resist you in terms of exposure.

In the following graph you can check which are the effects of each of these the following order: aperture, shutter speed, and ISO.

What is the diaphragm opening?

The opening is the hole that allows light to enter. Its maximum size depends on the lens, which marks the maximum and minimum aperture. The bigger the hole (smaller f-number), more light will enter. It is related to depth of field or area of ​​focus from image. Larger aperture, smaller area in focus in the image; smaller aperture, larger area in focus.

diaphragm opening

What is shutter speed?

shutter speed or rate of fire is the time the shutter is open when taking a picture.

The shutter is the mechanism that allows light to pass through so that your photography is possible. What you want to know is that the faster that speed, the less light will enter the sensor, and the slower, the more light.

What happens, as you saw in the secondary effects graph of the exposure triangle, is that, in addition to more light, movement is also captured, which is why some of your photos come out blurred.

Easier still, Mario explains it to you in the following video in a very simple way and with a very clear analogy, in case you have any doubts with my explanation. And in this article I explain how to master it to achieve impressive photographs.

What is ISO?

ISO is the sensitivity that the sensor of your camera has to capture the light of your photograph. The higher the ISO number, the more light your camera captures, that is, you need less light to enter through other channels (shutter speed or aperture) to expose your photo correctly.

At lower ISO, therefore, lower sensitivity, so you need more light to expose correctly. I leave you a graph to see it clearly.

You might think it’s easy, you upload ISO and that’s it, but here we also have a side effect and that is the noise that appears in the photos, as indicated in the graph. Let’s see a comparison, on the left an image with ISO 3200 and on the right the same shot with ISO 100. Do you see the difference?

ISO 3200 (left) and ISO 100 (right)

You can raise the ISO value when you need more light because you can’t adjust the other two parameters anymore, however, always keep noise levels in mind.

What is the maximum ISO I should use?

If you wonder what it is the maximum of ISO, there is no correct answer. Some cameras support higher ISO values ​​with less noise. It also depends on the type of photography, some photos allow more noise without spoiling the photo, others, due to their theme or destination, require greater sharpness and you should not abuse it.

The important thing is to know your camera and to know from where the noise bothers you and when you can cross that limit and when not.

When should I raise the ISO value?

When you are using the maximum aperture that your subject and the scene can support and when a slower shutter speed would spoil the photo with movement.

Very dark scenes, concerts, indoor photos, etc. will require you to raise the ISO value. You should also lose the fear of uploading it when the moment is key, if the question is to have a photo or not to have a photo of a special or very important moment, it is better to raise the ISO value. Without fear 😉 .

However, I do not recommend it if you are looking for sharpness in your photo, in macro, product photography, nature photography, etc. In these cases it is better to play with the other two parameters of the exposure triangle.

What are the steps in photography?

The steps in photography measure the increase or decrease in light input. Increasing one step implies doubling the light input; to reduce one step is to cut the light input in half.

If you jump a value on the aperture scale, you are jumping a step (a stop), going up or down. For example, from f/1.8 to f/2.0 there is one step, in this case, by closing the diaphragm one step, you reduce the light input by half. The same happens if you reduce the shutter speed by one step, from 1/250s to 1/125s, you reduce the light input by half.

Be careful that some cameras have half step scales or of a third step. You can see it in the configuration of yours. Here I leave you as an example the opening scales of a half step and a third of a step.

One-half step and one-third step aperture scales

What is the Law of reciprocity?

To explain it in a simple way, we will say that the law of reciprocity is the one that says that in order to maintain the balance of the exposure triangle, starting from a correct exposure, if you modify one value, you have to modify another of the values ​​to the same extent.

That is, suppose your image gives a correct exposure with, for example, the following values:

Now, the subject of the image is moving very fast and you have to use a faster speed because you want it to appear sharp, so you would change, say, two steps the shutter speed, let’s say 1/500s. As you have changed the speed two steps, you have reduced the light input, so to get a correct exposure again, you must move one of the other parameters, or both to recover the balance of the triangle. You can raise the ISO value, open the diaphragm or both, for example, with the following values ​​you would get the same exposure if the light conditions do not change.

  • ISO200
  • f/2.0 (two steps are modified by adding light)
  • 1/500s (two steps are modified by subtracting light)

Let’s see it with examples to make it clearer. These photos seem to be taken with the same parameters because they are exposed equally, or so it seems, right? Well, if you look at the parameters they are different, but, following the Law of Reciprocity, I have compensated the different values.

ISO 200 f/2.8 1/125s ISO 400 f/2.8 1/250s ISO 400 f/4.0 1/125s

What is white balance?

White balance is the tool your camera offers to correct the color cast of the light in your photo.

Have you ever noticed that your images have a more bluish or orange color. This is because light has temperature, but we are not going to delve into this topic. What you want to know now is that in your camera you have the option to correct said dominant when you are not interested.

For example, in the comparison below, you can see the left image with a warm cast while the right image has been corrected and shows a more neutral color.

On the left orange dominant color, on the right image with white balance corrected

This correction can be done in the processing or on-site, helping you white balance. Every situation you find yourself in requires an adjustment.

Let’s see the following graph, for now forget the third column that is the one that refers to the temperature of the light. If you are going to use flash, for example, set your camera to the white balance of the flash icon, the lightning bolt. And if, for example, you are on a cloudy day, adjust in mode cloud. These settings will cause the camera to correct those color casts in every situation.

Now, it is not always convenient for you to correct these dominants, perhaps you are precisely looking for that warm tone that the sunset light brings to convey certain emotions to the viewer. In that case you don’t have to correct it, obviously.

warm sunset light

And, when in doubt, with natural light, in most cases the sunny mode will work for you. The automatic if you are going to be changing light conditions, for everything else, the RAW mode saves your life 😉 .

What is the photometer?

A photometer is a device that measures light and serves to indicate which diaphragm or speed we should use in each situation. Fear not, normally a photometer is used by professionals or advanced users, read on for what you are most interested in knowing.

What is the exposure meter?

The exposure meter it is the internal light meter of your camera. It is the tool you have to measure the light exposure in your photography.

When you look through the viewfinder or on the screen of your camera you see a graph like the one I boxed in red in the following image. If the exposure meter is at 0, it usually means that your photo is well exposed. However, if it is towards +2 it means that it will be overexposed, that is, burned or with too much light. On the contrary, if it leans towards negative values, it indicates that there is an underexposure, therefore, the photo will be dark.

Don’t look at right or left, because whether the positive or negative values ​​are on one side or the other can change depending on the brand. And in some models it is even customizable.

exposure meter

To move this exposure meter to the center or zero value, which is where it normally should be, you can play around with the light triangle parameters. Take a test and you will see. If you’re at +2, for example, lower your shutter speed, or stop down. If you are at -2, you have several options, including raising the ISO value or opening the aperture. Everything will depend on the available light and what you are looking for in your photo, but don’t lose sight of the light meter, which will tell you if you are on the right track or not 😉

If you cannot move the exposure meter right to the center, but you can leave it close, make sure it is in negative values ​​close to zero, it is better to underexpose slightly than to overexpose so as not to burn certain areas from which you will not be able to retrieve information later.

How do I get more light in my photography?

If you have read the previous questions with their corresponding answers, you will already know that you have three options to capture more light and that you must choose the one/s that most interest you:

  • Opening the diaphragm (with f/numbers…