Photography 101 : ISO

a comprehensive ISO tutorial designed for bloggers

One topic we keep getting questions about is photography and there’s no question why. Gorgeous imagery is one of the easiest ways to set yourself apart on the internet. But, spoiler alert, it’s actually not all about having good camera or the right lens.


There seems to be a misconception out there that if you have a specific camera or lens, your photos will suddenly look amazing. Sadly, this is false. The real key to getting great images is knowing how to work your camera. No, I’m not talking about knowing how to turn it on and select the automatic settings, I’m talking about the manual settings. Eek! I know, they look scary and sound confusing, but over the next few weeks, I’ll be breaking down the three pillars of photography (ISO, aperture and shutter speed) into bite-size chunks that are easy to understand so you can practice at home.

Today, we’re starting with ISO. If you’re scratching your head wondering what the heck I’m talking about, let me explain! ISO or film speed refers to how sensitive your ‘film’ is to available light. A low ISO like 100 is not very sensitive to light which makes it perfect for bright, sunny shots, while 800 is far more sensitive to light, making it better for indoor or low light settings.

Let’s go over that once more because it’s that important!

For low ISOs (100-400), think outdoors on a sunny day and really bright lights.
You’ll want to use a high ISOs (500-3200) when you shoot indoors, at night or during a darker, cloudy day. Think indoors, night time and dark stormy days.

For the most part, you want to shoot at the lowest ISO possible when the lighting allows for it. The lower your ISO, the crisper your image will appear. As you get up into the really high ISOs, your image will get grainier, so when you can, always shoot at the lowest ISO possible. There’s plenty of times when shooting at ISO 100 is simply not possible, and that’s okay! I actually shoot on ISO 250-400 most of the time and only use ISO 100 when it’s super sunny! When I’m shooting indoors, I shoot at ISO 800 frequently and my images still turn out beautifully. It’s really only when you get into the super high ISOs (think 1250 and up) that I really start noticing the grain.

How do you know when should you increase it? When there’s not enough available light to quickly capture an image. The other half of creating a crisp image is a fast shutter speed, which we’ll get more into at a later date. If you’re shooting at a low ISO, but noticing that your shutter speed has to be really low to get enough light, then it’s time to bump up your ISO. Your camera can capture all kinds of lighting situations, it’s all about knowing when and how to adjust your settings to get the desired outcome.

Okay, let’s look at a few examples! I set up a shot here on my tripod and shot it at 3 different ISOs. Another thing you’ll notice is that in each of these shots, it’s not just the ISO that’s changing! The shutter speed had to be adjusted to make up for the difference in light. I also want you to look at the quality of the image as you go through them. As the ISO goes up, you’ll see more noise, or grain, in the image.


iso tutorial for bloggers

(ISO: 200 | Aperture: f/2.5 | Shutter Speed: 1/30)

I had to lower my shutter speed very low in this shot and would not recommend ever going this low! You’re likely to end up with a blurry shot. This was taken on a tripod which removed the human error. This ISO was too low for the available light.

what is ISO

(ISO: 800 | Aperture: f/2.5 | Shutter Speed: 1/125)

I have to admit that it was pretty grey day when I shot this, and usually I would prefer my shutter speed to be faster, but this isn’t too bad. This image could easily be captured clearly with no tripod.

how to work your camera's manual settings

(ISO: 6400 | Aperture: f/2.5 | Film Speed: 1/1000)

In this shot, you’ll notice that the image is grainy. It was a grey day, but it wasn’t dark enough for me to need to go to ISO 6400, but now you can see what kind of results you get!

Do you see the difference between them? The biggest difference is with the last one, it’s grainy and doesn’t look that great. The only time you’d really need to shoot at this ISO is outside on a dark night. But, for blog images, I always always recommend shooting in good natural light. It will always provide you with the best, most crisp images, and that’s what we all want, right?!

Well, that’s it for ISO! Like each of the pillars, it’s important to fully understand how ISO works to consistently get beautiful images. So, grab your camera, move the settings to manual, and start playing around! If you can’t figure out how to change the settings on your particular camera, simply Google it and find out where to move the settings on your exact camera model or just play around until you figure it out! Stay tuned over the next few weeks because I’m sharing tutorials on the other two pillars and you’ll want to learn those as well!

If you’re just getting started and looking for recommendations on photography equipment, check out our guide to DSLR cameras and lenses! And read more of our photography tips here!

Questions? Leave them below and I’ll try my best to answer!

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I'm Blair Staky—I help women turn their blogs into thriving businesses by sharing my secrets to growing a 6-figure blog. I'm so glad you're here!

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