Photography is light. As a photographer, with your SLR camera in your hands, you have 3 factors with which you can play to obtain a greater or lesser amount of light in your photography (to go deeper into lighting in photography, do not miss this very complete guide). In the previous article Alexa explained to us what the steps in photography were, we saw that we could increase and decrease the light by playing with the aperture, shutter speed and ISO sensitivity. But, if any of these 3 factors allows the light to be raised or lowered, which one should be touched in each situation?
Although aperture, shutter speed and ISO, all 3 allow the light to be raised and lowered, they do not do it in the same way, they do not offer the same result, and each of them has certain “side effects” that should be known. Therefore, if you need to increase or decrease the amount of light in a photo, depending on the situation, only one of these 3 factors is ideal.
How can you figure out which of the 3 (speed, aperture, ISO) to touch?
I’ll tell you next. This is going to be a very detailed article, with lots of explanations and examples, so give it the read it deserves, with a good cup of your favorite drink. Make yourself comfortable, and to the mess 😉
Review of how manual controls work in SLR photography
Photography is a matter of pure balance. You need to get the necessary but fair amount of light. Capturing low light would affect a very dark, underexposed photo. On the other hand, going too far with the light would lead to an overexposed result, too bright, and we don’t want that either.
To understand which of the settings should be touched according to which situation, it is convenient first to review the 3 elements or controls that intervene in the exposure.
Aperture (symbol A or Av on SLR cameras)
It is the diameter of the lens opening, which is where the light passes through. The larger the opening, the more light enters. It is like a water faucet, or a pipe, the larger and wider the flow, the more water passes. The narrower and smaller, the less water would pass through, and in photography the less light would enter. Here is an example of 3 goals. The one on the left has a very wide opening; the one on the right, a medium opening, and the central one has it extremely closed.
Aperture is expressed with the symbol f/. Be careful, do not be fooled by the number, because it usually expresses a value in reverse. f/1.4 symbolizes a very large aperture (one that would let a lot of light through), whereas f/16 represents a very small aperture (that would hardly let any light through).
In my camera I see the opening here where I point it out in the picture. In yours it should be a style more or less.
Shutter speed (symbol S or Tv on SLR cameras)
This is simply the speed at which the camera captures the image. If we choose a very fast speed, we will obtain a photograph with a minimum amount of light. If we use a slower speed, our photo will have more light.
Again, think of the water faucet. You get less water in the glass by turning the faucet on and off immediately than by turning it on and off after a few seconds. In photography it is exactly the same. The water is the light. If the speed at which the shutter opens and closes is slow, a lot of light passes through. If that speed is so fast that before the shutter has finished opening the shutter is already closing, then hardly any light will pass through 😉
Shutter speed is expressed in seconds and fractions of seconds. A shutter speed of 3 seconds would be expressed like this, with the number 3. If we put it for half a second, we would see it in the camera like this 1/2. A tenth of a second is 1/10 and a fraction of a 500 of a second would appear as 1/500.
For example, a photo shot at a shutter speed of 1/500 is much faster than one taken at 1/100, so the former will capture less light than the latter.
That we are short of light with the 1/100? We slowed down the shutter speed even more, and tried 1/50; 1/5, or even 1 second, let’s see what happens. And so on until we get enough light.
Here you can see how it puts it on my camera. I have the shutter speed here set to 1/500. As you can see, my camera skips the 1/, and shows only what comes after it. In this case it shows me 500 referring to 1/500.
ISO
This is the sensor’s sensitivity to light. If we shoot the photo with a very high ISO value, with the same aperture and shutter speed settings, the camera will capture more light. A lower ISO (is ISO male or female? ok, I’ll leave it at that) would result in a photo with less light. The ISO is also expressed with its corresponding number, and usually goes from 100 onwards. An ISO of 100 is considered very low. 1000 would already be a relatively high value.
By now you know perfectly well what is the aperture, shutter speed and ISO for. You even know which direction to move each of these settings to get more or less light.
But wait. If you can control the amount of light you capture with your camera simply by fiddling with your shutter speed, then why bother using the other two settings? ISO, opening…? So that? Simply by controlling the shutter speed you should be able to regulate the amount of light you need. You put a slow shutter speed and period. Instead of a speed of 1/800 for example, you lower it to 1/200 and that’s it. Isn’t that enough? You leave it even slower, at 1/2. What do you need more light yet? You fire it at a speed of 1 second, 2, or even 10 minutes if you feel like it. God. Can you imagine the amount of light your camera could capture by leaving the shutter open for 10 minutes? That’s it, problem solved. Who wants to touch an aperture or an ISO sensitivity?
If I can control the light with one of the 3 settings we have seen, why do I need the other 2?
When I’ve quickly explained shutter speed, aperture, and ISO back in this article, I’ve left out a very important part of how each one works, and that’s the side effects. Please don’t rush your camera to practice these adjustments without knowing about these side effects. here they go
The shutter speed offers you a greater or lesser amount of light, accompanied by a certain effect, which may or may not interest you. Now we will see.
With the opening, the same thing happens. By changing its values you can have more light, but that entails a certain effect that in turn may come in handy or not.
If you think that the same thing happens with ISO sensitivity, and that modifying its values to have more or less light, we would end up having some secondary effect, you are totally right 🙂
Side effects associated with the use of…
A slow shutter speed
Shutter speed, in addition to the light theme, influences how sharp and frozen, or blurry and shaky the image is.
As we said at the beginning, a slow speed would give us large amounts of light, true, but it would also cause a very shaky or blurred image. If we use a slow shutter speed, and during the shot the subject moves (even slightly) or we ourselves move with the camera, goodbye photography. Wanting to remedy the issue of light, we could end up with a new problem, which is that of the blurred or moved photo.
In what situation could we increase the light by slowing down the shutter speed while being sure that the photo is not going to be blurred? Simply ensuring total stability on both the subject and the camera. A subject standing, or in a difficult posture, will be more likely to vibrate or move, while if they were sitting, lying down, or leaning comfortably on something, they would have an easier time staying still during the shot.
The same for the camera, if we leave it on a good tripod, well stabilized, it is normal that it does not suffer much movement.
Now you know, use the shutter speed to increase the amount of light in the photo only when you are sure that the subject and camera will remain still during the shot. If you don’t have that guarantee, if you don’t have a way to stabilize the camera, or if what you intend to photograph is precisely a subject (or object) in full movement, I recommend that you put the shutter speed aside for a moment and try to increase light by other methods.
Which? We still have 2 left.
A very large opening
Large aperture, remember, would be a high f/ value.
Let’s put ourselves in a situation: we have a spectacular landscape in front of us (like the ones we explain how to capture in our landscape book), which cries out to be immortalized for later. You take your camera out of your backpack, frame, focus, and shoot. Oops, underexposed photo. You look at the aperture settings and see that the value is f/11. “Hummmm… this is a very small aperture, I can increase it and thus I capture much more light”you think
One moment. You are facing a landscape and you want the entire photo to come out of focus. You are not looking to highlight the beauty of a particular poppy, or of a trunk, no no, you want to portray a splendid panoramic landscape, so you want everything to come out in focus.
If you increase the aperture (lowering the f/ value on your camera to f/3.5 for example) you will run into a new problem called depth of field.
Don’t worry, don’t be scared by the term. I have an entire article dedicated to explaining what depth of field is, but in a nutshell, it’s how wide or narrow the area of focus will be. Have you ever seen a photo where the object or subject is in ultra-focus, while things behind it in the background are blurred and out of focus? Those are photos where the depth of field is very small. There, we have intentionally told the camera to focus on a particularly small area, that of the subject’s face or the object in question. We were interested there, but here, in front of this great landscape, we precisely want a very, very wide area of focus, so we need a large depth of field.
Returning to our landscape, if we enlarge the aperture (by reducing the f/ value) we will also be able to reduce the depth of field. We run the risk that the camera focuses only on the grass in front, and that those trees in the background, mountains or clouds appear all out of focus.
Do you more or less follow me?
In other words, increasing the aperture will give us huge amounts of light, but as a side effect it will reduce the depth of field. If we are not interested (like this time), we need to find another solution.