photography tips, part 2 | understanding aperture, shutter speed, iso and exposure


Before I discuss shooting in manual (we’ll do that in a later post), let’s learn about the most important aspect of photography: exposure. In a nutshell, exposure is the amount of light that enters the camera when you take a photo. This is dependent on 3 different factors — aperture, shutter speed, ISO. So let’s talk about understanding aperture, shutter speed, ISO and exposure.

Exposure Triangle: Understanding Aperture, Shutter Speed and ISO


Aperture is the size of the hole in your lens. This opening allows light to travel through and you can determine how much by adjusting the f-stop number. The lower the f-stop number, the bigger the hole and the more light that enters through the lens. The higher the f-stop number, the smaller the hole and the less light that enters through the lens.

Aperture also controls depth of field. If you set your camera to a low f-stop number and the hole is wide open, you will get more blur or bokeh in your photographs. If you set your camera to a high f-stop number and the hole is smaller, more of the photograph will be sharp. I use lower f-stops for portraits and higher f-stops for landscapes.

Your f-stop depends on the type of lens you’re using so let’s look at an example. If I were to look at my 50mm 1.4, I’d notice that the lowest number possible is f/1.4 for that particular lens. The highest number for my fixed lens is f/16. That means I can adjust my f-stop from 1.4 – 16 depending on the type of photo I want to take.

Remember this if you ever get confused
Low f-stop = big opening, more light, shallow depth of field (bokeh)
High f-stop = small opening, less light, large depth of field

Understanding Aperture

Do you know how to adjust the f-stop on your camera model?

Shutter speed:

The shutter is what allows light to hit the camera’s sensor to record an image. It’s important to understand shutter speed so your images aren’t under or overexposed.The more light that is let in, the shorter the shutter speed needs to be to record an image. In low light conditions the shutter speed needs to be longer to allow enough light in to record an image.

When hand-held shooting, I always remember that my shutter speed needs to be at least 1/60. If I’m using a lower shutter speed, I’ll pull out my tripod. Definitely use a tripod when you’re goal is to blur movement with a low shutter speed (i.e. lights from a car, people walking, etc).

Here is a little graphic about shutter speed and action:

Understanding Shutter Speed


This is the measure of the sensitivity of the image sensor. The lower the number, the less sensitive to light. The higher the number, the more sensitive to light. When you increase the ISO number, your sensor can capture images in low-light situations. However, increased sensitivity means more noise.

Noise is another word for grain in a photo. The next time you increase your ISO to capture a picture in low light, examine it and I bet you’ll see grain. You should try to keep your ISO around 100-200 for highest image quality.

Understanding ISO

And that’s your photography lesson for today. I’ll be back later with a few exercises to better your understanding of the exposure triangle.

If you missed part 1 you can read it here.


Filed Under: Photography26 Comments
  • Nicole @ Treasure Tromp

    this is excellent, Rachel!

    • Rachel

      Thank you, dear! Hope it helps!

  • Bangkokgirl Blog

    Thank you for such a clear and helpful post. I am working on my night shots at the moment and so am hoping to now put some of your tips into practice.

    • Rachel

      Hope it helps!

  • Dee

    This has always confused me so I don’t use the manual mode on my cam which is a shame. Thanks for this! Will put to use once I get my cam back from Canon.

    • Rachel

      Let me know if you have any questions!

  • Lisette

    Yay yay yay yay yay I’m so glad you posted this!!!!

  • Irene @ Away from Tenerife

    Great photography lesson, Rachel!
    I (finally) got myself a DRLS camera a couple of months ago and I haven’t messed around that much with the manual mode yet. I remember having learnt this but you’ve explained in a very clear way with very useful graphs. I might even print this post to have it near while practising at home :)

    • Rachel

      I really hope it helps you understand your camera! I’m a visual learner so the graphs help me a lot. :)

  • Lix Hewett

    I use and adjust all of these things on a regular basis but this is still super helpful for me because most of the time, I can’t name what I’m doing in actual words. So it’s super great to see the words and functions matched up so clearly! Thank you.

  • Niki Caron

    Great tips as always! I love learning all this photography stuff from you!

  • Rachel Murphree

    These are great tips! I haven’t really taken my camera into manual mode yet, but this helped me understand more of what it all means. Thanks!

    • Rachel

      I’m glad it helped!

  • Tina @ Girl-Meets-Globe

    I really like learning all this stuff, I just can’t remember it!! You’ve made it very simple, so that helps. I guess it’s just repetition and getting out there to practice it over and over again.

  • Kayli Schattner

    YOU. ARE. AMAZING. I needed this! Looking into buying my first DSLR and am trying to soak-up as much information as I can before the purchase :) thanks for this, beautiful!

    • Rachel

      I hope it helps!

  • From Casinos To Castles

    Totally pinning this! I think this is the first explanation I understand! I’m a visual learner so the pictures were helpful!

    • Rachel

      I’m a visual learner too! I tried reading my photography manual once and was so confused!

  • vintagezest

    So helpful! I am pinning for later, when I attempt to take good photos on our next trip, for once! :)

    • Rachel

      yay! I hope it helps!

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  • Sarah // The Quixotic Chica

    I really appreciate these tutorials. Ever since switching to Manual (eeee!!!!), I’ve been running into some problems with over/underexposure, and I realize now that I have been completely ignoring shutterspeed! This will help on my next photo excursion. Thanks, Rachel!

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  • Tatiana Muse

    This was extremely helpful! I recently got a new DSLR camera and need some tips. Thank you!

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