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What is ISO in Photography and Why is It Fundamental? 

What is ISO in Photography and Why is It Fundamental? 

Your camera is a technological marvel capturing light and transforming it into images. ISO is a useful measuring system to ensure you’re getting the ideal amount of light for your photo.

Without proper lighting, your photo runs the risk of dipping into visual extremes. Not enough light reaching your camera results in a murky and dark photo that’s hard for the viewer to read. Too much light goes in the opposite direction and bleaches everything out. How do you find a happy balance?

Becoming comfortable with photography means becoming comfortable with measuring light. By the end of this article, you’ll understand how ISO works and how to apply it to different settings.

Source Image: Pixabay

Table of Contents

  1. Introduction
  2. What Is ISO In Photography?
  3. What Are ISO Settings And Why Do They Matter?
  4. When Should I Use High ISO?
  5. When Should I Use Low ISO?
  6. How to Adjust ISO on Your DSLR Camera
  7. Conclusion: Learning Your Way Around ISO Will Create Crisp and Well-Lit Photos

a photographer in a gray shirt taking a photo of themselves in a small mirror below a row of books and bottles

Source Image: Pixabay

What is ISO in Photography? 

ISO is a value system that refers to how light enters the camera. These values are vital for helping accurately capture subjects, settings, and times of day.

When you understand how to use ISO, you’ll be able to achieve the following in your work.

Reducing Troublesome Noise

Noise is a term for pixelated spots that appear in your photo after it’s processed. Also known as grain or film grain, this issue frequently crops up when an ISO level is far too high.

The reason your camera sensor creates noise is because it’s attempting to compensate for not receiving enough light. However, it’s worth noting that a little noise can be used to fantastic effect in stylized artistic photography. Some photographers appreciate the vintage stylings of a little film grain and will use it to create a photo with a nostalgic or mysterious mood.

Eliminating Motion Blur

Another feature of using appropriate ISO settings is eliminating motion blur that can leave your photo smudgey and unreadable. You can reduce motion blur further by adjusting shutter speed.

Depending on the camera you use, your equipment may automatically compensate for mismatched settings. For example, your camera may instantly switch to a low shutter speed if your ISO setting isn’t capturing enough light.

Maintaining Strong Contrast

Capturing the right amount of light is paramount to creating a photo with striking contrast. A balanced ISO setting won’t be too bright or too dark so your subject is readable to the viewer.

If you’re not able to capture enough contrast from the start, never fear – a few beginner Photoshop tips can clear that up afterwards.

What’s the Difference Between ISO and Shutter Speed?

It’s easy to get these two confused since they both affect details such as light exposure and motion blur. To clarify, ISO affects how sensitive the camera sensor is to light, while shutter speed affects how long a shutter is open to receive said light.

They’re separate functions that you can adjust independently. For example, some photographers prefer to raise their ISO setting with fast moving subjects. However, others may instead choose to increase their shutter speed.

Is ISO the Same Thing as Exposure? 

Exposure refers to how much light is reaching your camera’s sensor. Where ISO comes in is how sensitive that sensor is to light and whether that sensitivity translates to a well-lit photo.

Basically, raising your ISO setting in a low-lit environment will increase your chances of balanced exposure. However, if you used a low ISO setting in a low-lit environment, your photo would lack exposure and look murky.

a man in a hoodie standing by a beach in a low lit evening against a blue and pink sunset

Source Image: Pixabay

What are ISO Settings and Why Do They Matter?

ISO settings are a simple metric to determine how well-lit and crisp your photos appear. While aperture is measured in f/stops, ISO settings come in numbers ranging from a few hundred to a few thousand.

Low ISO Settings

A low ISO setting is useful when you already have a strong light source to work with. The 100 to 200 range is as low as you can get, generally preferred in daytime settings or well-lit studios.

Average ISO Settings

The middlerange of ISO is 200 to 800, ideal for when your lighting isn’t super dim or super strong. The 200 to 400 range is fine for indoor environments with a dominant light source such as an overhead lamp or nearby daylight.

The 400 to 800 range is useful for when the light source is starting to dim, such as during the evening or a low-lit indoor environment. 

High ISO Settings

Once you step beyond 800, you enter high ISO settings. These numerals are much more drastic, ranging from 1,600 to 6,400. 

The 1,600 to 3,200 range is most popular for nighttime environments, whether they’re indoors or outdoors. The most extreme setting of 6,400 should be saved for the darkest environments, though there will likely be a lot of noise.

an example of low lit ISO photography showing a sunset by the beach with palm trees

Source Image: Pixabay

When Should I Use High ISO?

Dim and dark environments are best suited to high ISO so you can increase exposure. The following tips will break down a few starting points.

Low Lit Evenings

Do you want to take a soothing photo of a low lit evening? An ISO setting of 400 to 800 will help you capture more detail and contrast for a clear photo.

Dark Indoor Environments

Whether you want to take moody photos of your studio or nighttime shots of your front porch, you’ll need a high ISO setting to match. The 1,600 setting is good for darker indoor settings, though be mindful of the higher grain count.

Night Sky

The night sky is tricky to capture due to the lack of natural light and subtle scatter of the stars, but a higher ISO setting will do the trick. The 3,200 to 6,400 range is needed to make up for the lack of surrounding light, though a moonlit night may fare fine with 800 to 1,600.

When you want to improve your astrophotography, pairing ISO with a 50mm lens will do wonders for creating a clear and sparkling photo.

a cluster of green grapes in a vineyard on a sunny day

Source Image: Pixabay

When Should I Use Low ISO?

Since the daylight is already doing most of the work, you don’t need to raise your ISO all that much. However, there are still a few subtle details that will require you to tweak your settings.

Bright Daylight

When the sun is shining and revealing your subject nicely, you can stay in the 100 to 200 ISO range. This setting will ensure you’re getting the least amount of grain possible.

Mildly Cloudy Day

If a few clouds dim your daylight, a lower ISO setting of 200 to 400 is preferable. This slight uptick will help your camera sensor adjust to the shift in available daylight to reduce grain.

Shaded Areas

What do you do when there’s daylight, but you want to shoot in a shaded area beneath a tree or an overhang? ISO settings of 200 to 400 will help your camera sensor compensate, though 700 to 800 could also work for heavier shade.

a photographer in a dark raincoat surrounded by misty hills and taking a photo

Source Image: Pixabay

How to Adjust ISO on Your DSLR Camera 

Adjusting ISO just takes a few steps, but each camera model will have their own variations on ISO settings. A modern DSLR camera – made in the last few years – will likely have a dedicated ISO button.

After you press the button, use the wheel slider to change the settings. Older DSLR cameras may instead have a digital menu where you can select your ISO setting. Be mindful that an automated setting (or Auto) will choose the ideal ISO for you, which may or may not yield the results you want.

One of the most reliable ISO tips is to get comfortable manually adjusting settings so you can adapt on the fly. After all, it only takes a cloud moving over the sun to completely change the needs of your photo.

an example of well used ISO showcasing a lavender sunset behind a bridge

Source Image: Pixabay

Conclusion: Learning Your Way Around ISO Will Create Crisp and Well-Lit Photos

When you’re tired of murky photos and unwanted grain, ISO settings will (literally) clear that up. Learning your way around these numbers will better prepare you for the needs of different settings. 

The function of ISO is to change your camera sensor’s sensitivity to light. In turn, this affects the exposure of your final photo to ensure your subjects are detailed and crisp. Lower ISO settings are best for environments that already have plenty of light, such as the 100 to 400 range. Higher ISO settings help you compensate for a lack of light, such as nighttime photography. As you learn your way around the best ISO settings, you can then pair them with different shutter speeds to further reduce grain or motion blur.

Thanks to ISO, you’ll be able to flip through a few settings and narrow down your next best photo.

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