Using Aperture to Control Light
Using Aperture to Control Light
In my previous blog, I talked about the inverse square law and showed you how to put it to use. This one will use some of the same settings but I will use a different technique to properly expose the photos, Aperture.
What is aperture? Simply put, aperture is the opening in the lens that allows light to pass through to the sensor or film in order to create an image. Think of the lens as your eye, the aperture is basically just like the pupil of your eye, it adjusts by opening wider or closing more in order to allow the right amount of light to enter your eye so that you see things properly. The aperture is basically the pupil of the camera lens. Aperture is measured in what we in photography call f-stops. Now, I am not going to get all technical and go into all of the detail because this is for mostly newer photographers. Just know this, the lower the aperture number, the more light allowed into the camera and the more shallow the depth of field. The higher the number of the aperture, the less light allowed into the camera and the depth of field becomes greater.
On to the experiment and the learning....
Previously, the experiment we conducted started with a speedlight set on 1/4 power, 12 inches from the ball. We used iso 100 as well as a shutter speed of 1/125 of a second. To learn the inverse square law, we doubled the distance between the speedlight and the ball until we had a properly exposed photo. We are going to take a little from that experiment and use it today.
First, we need our speedlight set on 1/4 power again. We will once again be using a shutter speed of 1/125 of a second and our ISO will be set to 100. We will start with our aperture, once again, at f/5.6. However, we will put our speedlight 24 inches away from our ball (that was the second distance in the previous lesson) at a 45 degree angle from the ball.
Everything set up? Aperture at f/5.6? Here we go... Take a photo of the ball.
What happened? The ball is seriously over-exposed right? Of course it is. We did the exact same shot last time... Now, lets start learning a little...
There are a couple of things I want you to notice.. The first of which is, the photo is very bright and overexposed throughout. The second thing I want you to notice is the background, do you see how it is blurry and not in focus? That is because we are shooting at a wide aperture f/5.6 (remember, lower number = more light, less depth of field).
Most lenses and cameras on the market today allow you to change your aperture by 1/3 of a stop. I am not going to get into the math and how you determine the numbers etc, but I will offer this chart - it is used with permission..
Notice the column that has the f-stops broken down by thirds. That is the one we will be following today.
As we move along in our experiment, I want you to close your aperture by 1/3 stop for each photo, all while keeping every other part of the experiment exactly the same. ISO 100, speedlight on 1/4 power, 24 inch distance between the light and the ball and so on. We will progress through the aperture scale until our photo is exposed properly.
Here is our next photo, taken at f/6.3
What do you see? Any difference?
Now, lets go to the next level, f/7.1
What do you see? Things are changing slightly right?
So, next would be f/8
Are you seeing the difference? Each step along the way there is slightly more change in the photo. The exposure is slowly creeping up on where we want it to be.. we still have a good distance to go, but it is no where near the level of over-exposure that we had to start with right?
Next we have f/9
We're really seeing the changes now...
and now to f/11
We're getting there.. you can see the magazine rack in the background starting to take shape. Also, you can see that I should have swept my floor prior to doing this!
Did you notice that as we moved higher and higher with our f/number the background became more and more clear? Did you notice that the light became darker and less overpowering? As we got to the end, we could see more and more details of the baseball. We could see the scuff marks and the dirt on it as well.
So, as we can see, aperture controls how much light is let in and we can control the exposure of our photograph simply by adjusting our aperture.
Taking what we learned previously about the inverse square law and using it with what we learned here will enable us to better expose our photos, even if we can not adjust how much light our speedlight or light source is putting out.
Stick around, there will be another lesson coming soon... Subscribe to my blog and my YouTube Channel to continue learning.
Nice article. I am learning video but this was very helpful. My main camera is a dslr and I have been wanting to snap some photos.
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