Photography 101: 9 Things You Need To Know About Aperture

Understanding your camera is key to getting great photos for your site. Want to get those professional, multi-dimensional photos like the pros, but only have a standard DSLR camera? It's all about the aperture, baby.

male legs orange round aperture

Things you should know about your aperture:

1. The aperture is the size of the opening in the lens when a picture is taken. When you hit a button to take a picture, a hole opens to allow the camera to capture the scene — the aperture you set affects the size of that hole. The larger the hold, the more light goes in, the smaller the hole, the less light.

2.  Aperture is measured in f-stops (you will see it referred to as f/number, like f/2.8, f/4, f/22, etc.).

3. Moving from one f-stop to the next doubles or halves the size of the amount of opening in your lens. Simply put, it doubles or halves the amount of light coming into your camera.

4. The one tricky thing you MUST remember — large apertures (where more light is let in) have SMALLER f-stops, and small apertures (less light) have LARGER f-stops. In context: f/2.8 lets in much more light than f/22.

5. The depth of field (DOF) is the distance between the nearest and farthest objects in a scene that appear acceptably sharp in an image.

6. Large depth of field means that most or all of your image (meaning both foreground and the background) is in focus, or sharp. For this effect, you want a larger f-stop, meaning a smaller aperture or less light getting in.

For example, most of the background is in focus, giving it a large DOF and a small aperture:

large DOF small aperture photot example

7. Shallow depth of field means that only a part of the image is in focus, and the rest will be blurry or fuzzy. For this effect, you want a smaller f-stop, meaning a larger aperture or more light.

For example, the background is blurry, leaving only the subject in focus, which is a shallow DOF and a larger aperture:

shallow DOF larger aperture photo example

8. One way to keep all this straight in your head: small f-stop numbers mean small DOF, and large f-stop numbers mean large DOF.

9. When you think about the type of photo you want to take, quantify whether you want a large or shallow depth of field and adjust your aperture accordingly. In most cases, landscape photography will have small aperture settings because they want a large depth of field. However portrait photography generally is shot with a focus on the subject and a blurry background (shallow depth of field), with a large aperture.

The best way to learn? Pick up your camera and practice! Soon it will be like second nature.

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About The Author

Ana is a Travel Blogger and Blogging Coach at The City Sidewalks. With her expertise in online marketing, she's able to help other bloggers, creatives, and entrepreneurs grow their businesses so that they can achieve financial freedom to travel the world on their own terms.

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18 Responses

  1. moiminnie

    Great post, I’ll deffinitely share it among my blog readers as many of them are constantly asking how I take my amazingly good looking photos. All of the answers are here, great summarisation !

  2. Becky Bedbug

    I find depth of field so difficult to manage! It has proved impossible for me to get a full-length image of myself with a shallow depth of field. I think I just need to get a different lens with the potential for a smaller f/ number.



    • Megan

      Hey Becky!

      What kind of camera/lens do you use? If you’re looking for a great portrait lens with super low f-stop, I’d recommend investing in a 50mm 1.4 or 85mm. I always shoot portraits and most of weddings with the 50mm and it has consistently GORGEOUS bokeh – you’d love it!


  3. Rachel W.

    I like the mnemonic for how depth of field and aperture relate!

    Is there any hope for those of us with mere point-and-shoot digitals? My wee Canon only goes down to f/2.6. No matter where I position my subject and how far away the objects in my background are, depth of field stretches into infinity, crystal clear all the way. I can *sort* of blur my background while shooting in macro, but that’s not very practical for outfit shots!

    I love the blurry/light-spattered background in so many blogger’s photographs: is that just impossible without a DSLR?

    • Megan

      Hey Rachel!
      An f/2.6 is actually pretty good for a point-and-shoot! That’s what I used before upgrading to my Canon 5D Mark II about a year ago. I’ve been shooting portraits/weddings for the past year and found that I could get a little depth of field without the DSLR but if you really want to have great bokeh (tons of depth of field with a blurry/light-spattered background), and a LOT more control over your shots, I’d suggest investing in a DSLR and a portrait lens – like a 50mm 1.4 or 85mm. Both are AMAZING for portraits/bokeh and would definitely take your outfit shots to the next level!

      • Rachel W.

        Thanks for the great response, Megan! I’m definitely saving up for a DSLR. This might be too involved of a question to tackle here, but d’you think I would be selling myself short by buying say, a $500 Canon DSLR versus of one of the $1000+ models?

        Whatever I buy, I know I’ll have to spring for the portrait lens– that’s priority number one after the camera itself!

      • Amber

        I bought my first DSLR earlier this year. I love it. After using a point and shoot for so long, I fell head over heels for my new Canon. Buying a DSLR within the 500-600 range won’t disappoint, trust me! You might be actually doing yourself a favor buying within that range, instead of buying a $1000 camera. There is nothing more embarrassing than seeing a blogger with a $1,200 camera and her not knowing how to use it. I’ve seen this, and it makes me cringe. A camera within the $600 range is still an amazing machine. As you get more comfortable you can always upgrade your lens, etc.

        Hope that helps as well!

      • Rachel W.

        Thanks for the advice, Amber! It’s encouraging to hear that at my level I wouldn’t be making a mistake springing for the (comparatively) cheap DSLR. I’ve been reading some Consumer Reports, and while (of course) the $1000+ Nikons perform well, the more-affordable Canons aren’t too shabby either!

  4. TerranceJ

    Great mnemonics for the aperture! My only issue now is actually being able to afford a DSLR 😉

  5. Jamie

    I haven’t taken a photography course since sophomore year of highschool, so this was an AMAZING refresher that will have me back to using my canon DSLR to its full potential in no time.

    Thanks so much!

    xo Jamie

  6. Ellie

    When I get home I’m going to try this out. Thank you for the adivce, I’ve had an slr for a year now and I’m pretty sure I’ve not been using it to it’s potential!


  7. Annie

    I love reading your tips on photography!
    Do you know how to get DOF on Panasonic lumix LX5? I am having hard times getting good quality pictures on it.

  8. Teri Roughen

    I’m so confused. I thought the F number goes up if you want a more focused photo, but down to 1. or 2. if you want to blur the background and it’s close up?
    But you’re saying landscapes or group shots, you should have a smaller f stop?

    • Campus Sartorialist

      Hey Teri,

      I think you have the settings confused. Modern Nikon lens only go down to 1.8/1.4 and Canon 1.4/1.2 with leica going down to 0.95 for a $10000 price tag.

      If you want to get technical the aperture number (1.8, 1.4 etc) is actually written out as f/1.4 and it’s the mathematical ratio of the focal length to the aperture diameter.

      An average 50 mm prime lens has a range of f/1.8 to f/16. If you calculate the values, 50/1.8 is larger than 50/16 which means the opening is wider and more light is coming in.

      All cameras, DSLRs or not have aperture priority modes labeled A or Av which basically tells the camera to set shutter speed, exposure and most times ISO while keeping the aperture at the value indicated for you.

      A lot of newbie photographers buy a lens with a shallow DOF and are so in love with the great blurring effect that they shoot all their photos at the widest settings. This compromises the overall sharpness of your photos and it’s advised as a rule of thumb to take your photos at one or two “stops” from your lowest setting. If you have a 85 mm f/1.4 shoot it at f/1.8, f/2 or f/2.2 for great DOF and incredibly sharp photos.

      If you’re interested in learning more about photography I suggest signing up to the Digital Photography School mailing list. I am in no way affiliated with the website. I just know it’s definitely helped me improve my technical and compositional skills in the past http://digital-photography-school.com/

      All the best,
      Campus Sartorialist

  9. AJ

    I never get tired of reading up on photography tips. Mine has continued to evolve since I started my blog. Each time I get a really great picture, I analyze everything in the exif data and compare it with the time of day taken, what kind of light was available, etc etc so I can continue to improve my pictures.

    I suggest bloggers just getting started with the subject of aperture shoot on aperture priority on their cameras, and open that sucker all the way up. I only recently started adjusting the settings manually, and the “A” setting on the dial (Nikon) worked for me 90% of the time.

    Keep it up! I think this post has some of my greatest pics yet and I know ifb deserves some of the credit! http://www.ajwearsclothes.com/2012/07/inspired-style-serena.html

  10. Nasreen

    knew this post would come in handy once I gt my DSLR 🙂 SO HAPPY!!