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Aperture f.18

Tuesday Tip: Aperture for Beginners


A couple weeks ago I did a post on ISO for Beginners and received some positive response. So, I decided to create another “for beginners” post around aperture. For most shoots I set my camera to aperture priority, because I enjoy adjusting the depth of field in my shots. Below is a brief technical summary of aperture and the best way (in my opinion) to grasp the concept: photos.

What Is Aperture?

According to Digital Photography School, aperture is ‘the size of the opening in the lens when a picture is taken.’  The larger the opening in your lens, the more light it lets in. The pupil in our eyes is a great real life example of aperture. When we’re in bright sunlight, our pupils are small because we don’t need a lot of light let into our eyes to see. The flip side is true when we’re in the dark; our pupils are larger because they are seeking light to allow us to see objects in the dark.

Digital cameras measure aperture in “f-stops.” For example, my 50MM lens has an f-stop of 1.8. Where many amateur photographers get confused is what these f-stop numbers mean. The larger the opening in the lens, the smaller the f-stop. So, a lens at an f1.8 has a much larger opening than a lens set to f22.


When Should I Adjust My Aperture?

Depth of field, as I mentioned above, is one of my favorite techniques to play with in my photos. Depth of field determines how much of your photo is in focus. Photos with a shallow depth of field (or a wide open aperture, such as f1.8) only have part of the image in focus while the rest of the image is blurred. Many photographers use this technique for flowers.  A large depth of field (a closed aperture, such as f22) means most of the photo is in focus. Landscape photos are usually taken with a large depth of field to capture all of the detail both near and far away.

Below are some suggestions for when you might use shallow depth of field versus large depth of field.

  • Portraits, especially when your subject is in a ‘busy’ setting
  • Flowers
  • Baby feet, hands, or eyes
  • Food photography


How Do Aperture Settings Affect My Photos?

To illustrate aperture, I took a picture of a strawberry on my kitchen table. I put my DSLR on Aperture Priority mode, so all I had to do is adjust the f-stop settings accordingly. Remember, wide open apertures (such as f1.8) have a shallow depth of field where the subject is in focus and the background is not. Narrow apertures (such as f22) have a large depth of field with everything in focus.

Aperture setting: f1.8

Aperture f.18

Aperture f3.2

Aperture f3.2

Aperture 7.1
Aperture f7.1
Aperture f22
Aperture f22
While the details on the strawberry are clearest in the last photo (with the most narrow aperture), the background is also in detail which detracts from the main strawberry image. The photo with the shallowest depth of field (f1.8) focuses the eye just on the strawberry.
Hopefully you found this quick description helpful.
Which type of photos do you normally take? Those with a shallow depth of field or a large depth of field? Comment below.
  1. Jason Stolken
    Jason Stolken05-07-2012

    Great post Wendy! Something that I can pass on is the result of something strange that happened to me. On my 18-135MM lens the aperture will open all the way up to 3.5 which is not bad for that lens. But the aperture never seemed to open up all the way when I was completely zoomed in at 135MM. I could only get it to 5.0. So my understanding is that when you are completely zoomed in, the lens will not allow the maximum open aperture. Is that true from what you have experienced?
    Jason Stolken recently posted..Fast Food Leads to Sh!tterMy Profile

    • Wendy

      Really good question! The short answer is…Yes, zoom affects your maximum open aperture. The more you zoom, the longer your lens gets, which means less light is getting to the sensor. So, at your maximum zoom…your aperture will be limited to a certain setting. From what I have read, there are zoom lenses out there with fixed apertures, but they’re pretty expensive.

  2. Sonel

    Now that is very interesting and thanks for sharing Wendy! I enjoyed and great shots hon. :)
    Sonel recently posted..Weekly Photo Challenge: UnfocusedMy Profile

  3. Basilia Lagarde
    Basilia Lagarde04-09-2013

    Fantastic website you have here but I was curious if you knew of any user discussion forums that cover the same topics discussed in this article? I’d really like to be a part of group where I can get advice from other experienced individuals that share the same interest. If you have any suggestions, please let me know. Bless you!

  4. aperture

    now i have more understanding about aperture. thanks to the author :) Kaycee McNally
    aperture recently posted..Guidelines and Tips for Group PhotographyMy Profile

  5. Raphael

    YE thank you to tell me about aperture and lm understanding well

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