December 23, 2021  •  Leave a Comment

F-Stop is the control knob for aperture settings and probably one of the harder of the three legs of the exposure triangle to grasp.  But it doesn't have to be.   I feel if you practice enough it will become second nature.  So grab your camera and we will get started with some F-stop exercises.  I created a youtube video on this same topic that will be live on 12/30/2021.  It shows me capturing the photos with some explanation as well.

To get started, set your camera to Aperture Priority Av (or A) mode on the dial.   Canon labels it "Av", and most of the others use "A".  If you have a green "A" that is automatic not aperture priority.   With aperture priority, shutter speed is set to automatic but you will need to ensure ISO is also set to automatic.  Having shutter and ISO set to automatic allows you to learn more about what different Aperture settings do.

Before you practice here are some good use cases for Aperture Priority

  • Portrait photography to get that Bokeh (blurry background)
  • When light conditions are rapidly changing (manual mode is near impossible for beginners in this situation)
  • Street photography is a common time to use aperture priority
  • Landscape photography to use a small aperture to get more in focus (aka no bokeh)

Do you have your camera?  I can wait.

Good.  I have mine too.

Now find a subject that has some background in the distance.  I will be using my stuffed Tigger, Winnie the Pooh, and Eeyore.

  1. Turn your camera on.
  2. Set dial to "Av" or "A" for aperture priority.
  3. Set ISO to automatic if not already there.

It also helps to have enough natural light to allow for small aperture settings and still get proper exposure.  While this exercise is about controlling aperture priority you should pay just a little attention to the shutter speed to make sure it is fast enough to work handheld.  For this exercise, if your shutter speed drops to below 1/50 of a second you need to get more light for this exercise.  We will leave it at that.

Showing Av SetShowing Av SetShowing Av Set
To set your dial to Av or A you may need to depress the center of the dial while turning.  Remember the Green A is Automatic.

Showing Auto ISOShowing Auto ISOShowing Auto ISO
Verify your ISO is on Auto.  If it isn't find the dial or button that has the letters ISO and push it to change the setting to Auto.

To adjust your aperture there should be a dial near your shutter button to change the setting.  Spin it to the desired aperture setting. 

Setting ISO to automatic is different on some cameras.  On my Canon camera, there is a button labeled ISO.   Once I depress that button, the same dial for adjusting aperture will adjust ISO.  Once ISO is on auto find a button labeled "set".

Now that your camera is ready to practice, set up your scene to play (try) all aperture settings.  I am showing the two extremes below with my 50mm lens to emphasize the difference.

F 1.8
ISO 400
SS 1/800 sec

Sharp PhotoSharp PhotoSharp Photo
F 22
ISO 4000
SS 1/50 sec

Notice the photo on the left with a very blurry background with the F-stop of 1.8.  This is a very common setting for portraits and gives a good focus on the subject.  The photo on the right is much sharper and your eyes will find the subjects in the background faster than the photo on the left.  This is not what I want on a portrait.  I want your eyes to stay on the subject and with a small (F 1.8) aperture that is what I hope happened.

How did your photos turn out?


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