What Is ISO In Photography?

what is iso

Setting your ISO is one of three keys to better and creative photos. The other two are your Aperture and Shutter Speed. 

But, what exactly is ISO?

Today, you’ll learn what ISO is (and isn’t), a brief history of ISO, and what ISO setting to use in different shooting situations.


Awesome, let’s do it…

ISO for beginners

Photo by one of our students: Mateusz Suska.
Izabela ~ Canon M50  |  50mm  |  f/6.3  |  1/100  |  ISO 100

Once you complete this article, don’t forget to take the Pop-Quiz!

3 of them in all.

You’ll find them in the ISO challenges (last section).

Table of Contents

This image is overexposed. Camera settings: ISO 400 | F/2.8 | 1/200

By lowering the ISO and keeping the same settings (as above) the image is now properly exposed.

Camera settings: ISO 200 | F/2.8 | 1/200

What Is ISO?

In essence, ISO is a camera setting that can increase or darken an image during capture.

“ISO is used to rate the sensitivity of film to light. The higher the ISO number, the more sensitive the film. The different ratings of ISO are known as film speeds.”

Ok, but you’re thinking…

“I don’t shoot film. What does this have to do with my digital camera?”

Well, ISO has been carried over from the film days, and the concept of ISO is similar for digital.

In the digital world, your photos will become brighter, the higher the ISO number. That is if your Aperture and Shutter Speed stays the same.

Therefore, your ISO setting gives you the creative option to choose a different Aperture and/or Shutter Speed based on the available light.

To better understand ISO, we’re going to take a short journey through the days of film. Feel free to skip it if you’re already familiar with the origin of ISO.

A Brief History + Origin of ISO Numbers

Before we had ISO (to rate the speed of film), there were several competing standards

Hurter and Driffield – Two scientists from the 19th century standardize the classification of the speed of film at that time (1890’s – 1928)… based on the film’s sensitivity.

Weston – This father and son team had a different method of rating film, and sometimes it conflicted with the manufacturer ratings. This led to confusion on what speed of film you were actually buying.

DIN – This was a competing rating system introduced by the Deutsches Institute Normung. It just added more confusion.

ASA – In 1943, the American Standards Association tried to standardize film ratings by taking inspiration from previous systems and created a new method for rating film.

ISO – In 1974, DIN and ASA were used for inspiration (and were joined) to create a new method to standardize the rating of the film. It’s still used today.

The new ISO standard streamlined the rating system by doubling the film sensitivity based on the numeric value of the film speed. And was adopted by film manufacturers… making it easier for photographers.

Common ISO Settings

Not all cameras will have the exact same ISO settings available.

However, there are some standard ISO settings that most cameras will have.

These are the same ISO ratings we had/have with film. 

  • ISO 100
  • ISO 200
  • ISO 400
  • ISO 800
  • ISO 1600
  • ISO 3200


Note: Some cameras will not have an ISO 100 rating. For example, my Nikon D300 does not have it. Nor do some other cameras.

Plus, some cameras have additional options that will be labeled as “HI and “LO”. I find these settings, mainly “HI”, result in poor quality images. So, I try to avoid these and recommend you do the same.

fuji iso 100 film
Fujichrome ISO 100 film.  This film (actually, it’s slide film) is rated for use in bright situations.

For example, under direct sunlight or other situations where the lighting is bright.

What Do The ISO Numbers Represent?

Rating the sensitivity of film was required, so you knew which one to use during specific lighting conditions.

The same applies to digital photography. Having a number that represents a brightness level, helps in determining which one to use under specific lighting conditions.

In low light situations, you would need a higher (more sensitive) ISO to be able to capture the image with optimal exposure.

For example, a scene lit by candlelight might require a fast (more sensitive) ISO, like 3200.

Shooting at sunset would require maybe 800 or 1600. On a bright sunny day, you may need a less sensitive (slower) film, like 100 or 200.

These are general assumptions. Technically you could shoot at ISO 100 the majority of the time. 

As long as you have a tripod so you can shoot at slower shutter speeds and have the lens “wide-open” (larger aperture).

Or if you’re able to increase the amount of light (flash, strobes, etc..), you could then shoot at a lower ISO.

So, numbers were assigned to film based on how sensitive it was to light. 

The higher the number, the more sensitive film is.

kodak iso 800
Kodak Portra ISO 800.  3 stops brighter vs. ISO 100.  ISO 800 is ideal for lower light situations: under heavy shade, sunset, indoors, etc.
ISO 3200
Kodak ISO 3200 B&W film.  5 stops brighter vs. ISO 100. 

This ISO rating is perfect for extreme low-light situations: candle-light, indoors with less intense lighting, (stadium), a night photography, etc.

ISO Doubles Your Light. Sort Of.

You’ll also notice that each ISO number is doubled or halved. 

Each time you double the ISO, let’s say from 100 to 200, your camera needs only half as much light for the same exposure.

The opposite is true if you go from 400 to 200… you’ll need twice as much light for the same exposure.

In general, the intensity of the light source is going to be a starting point for what ISO to use. 

You’ll also have to take into consideration whether or not you can allow more light to be captured through a larger aperture and/or slower shutter speed.

Depending on the circumstances and your creative vision, you may end up needing a faster ISO.

Low light scenes require a higher ISO setting.  In this case, ISO 800 was used due to the low light of the lamps.

The shutter speed was set to 1/100th of a sec. and an aperture of f/2.8.  The fast aperture allowed more light to enter.

Otherwise, if I used an aperture of f/5.6, an ISO of 3200 would have been required for the proper exposure.
A Google search lists a company called: “International Organization for Standardization.”

Which is not the same as “International Standards Organization.”

Where Did ISO Come From and How Do You Pronounce It?

Ask anyone that has been in photography for a while, and you’ll find that most will tell you that ISO is an acronym for; International Standards Organization.

And that you should pronounce it “eye – ess – oh.”

One problem, though. There is no such company called “International Standards Organization.”

Don’t believe me? Google it.

Nothing. Notta. Zilch. It doesn’t exist.

But, there is a company called the “International Organization of Standardization.” Which is not the same as the name above.

Where did “ISO” come from, and why the confusion?

As mentioned previously, there is a company called the “International Organization of Standardization.”

Which is not the same as the “International Standardization Organization.”

From their website

…the International Organization of Standardization is a non-profit organization based in Geneva, Switzerland.

Their mission is to bring together experts to share knowledge and develop voluntary, consensus-based, market-relevant International Standards that support innovation and provide solutions to global challenges.

However, they made things confusing by adopting “ISO” vs. IOS. Here is a quote from the International Organization for Standardization website…

“Because ‘International Organization for Standardization' would have different acronyms in different languages (IOS in English, OIN in French for Organisation Internationale de normalization), our founders decided to give it the short form ISO.

ISO is derived from the Greek isos, meaning equal.

Whatever the country, whatever the language, we are always ISO.”

ISO logo
ISO is a brand.  Above, is the logo for: “International Organization of Standardization.”  There logo is trademarked and is presented here only for educational purposes.

Therefore, ISO does not stand for: “International Standardization Organization.”

The Truth

ISO is their brand! It’s not an acronym. Coke is a brand (which is better than Pepsi, by the way). Not an acronym.

As they mentioned, they use the short form ISO, which is derived from the Greek word isos.

So, ISO is a word.

Pronounced: “Eye-so.” Not I.S.O. (or C.O.K.E.).

Now, here is the real question…

Does It Really Matter?

In the grander scheme of things… no. It’s not going to make you a better photographer.

Truth be told, I’ve been saying “I.S.O.” for 25 years! I had no idea until another photographer informed me of the truth. But, my level of photography didn’t change one way or the other.

Let’s move on…

Shot in 1989 with a Nikon 8008.  Kodak Portra film rated at ISO 800. 

In the early days I had no idea what I was doing.  800 was way too much for a daytime shoot.
Shot in 2010 with a Nikon D200. You wouldn’t know that this was shot in the middle of the day!

This little alley is next to a fire station in Downtown Detroit and provided little sunlight.  Due to the low intensity of light an ISO of 800 was used.

How ISO is Different in the Digital World

The first difference, with ISO in the digital world, is concerning how your digital camera processes the ISO settings in-camera. This explanation will help you better understand how ISO works.

Are the sensors in your camera sensitive to light?

In the analog world, film is sensitive to light. In the digital world, your camera sensor is NOT sensitive to light.

Why “film” is sensitive to light.

Film is made up of different layers. One of which consists of the emulsion. The emulsion is sensitive to light. When exposed to light, an image (of the scene) is “burned” into the emulsion.

For a full scientific explanation, seek out this article from Kodak.

Why the sensor in your camera is NOT sensitive to light.

Our camera’s sensors are made up of electronics. Electronics are not sensitive to light. It gathers the information, from the light, and records it electronically.

For a more technical explanation, check out this post from Wikipedia.

How ISO is Processed by the sensor in your camera

We’ve established that our camera’s sensors are not sensitive to light. Then, the question is, how does ISO affect the brightness of an image?

Technical Answer

Two things have to happen with your camera sensor to capture your photo.

In-studio portrait shot at ISO 100.  Lit with an Ultra 600 White Lightning strobe.

  The strobe provided plenty of light to shoot at the lowest ISO setting.
Outdoor concert in Leamington, ON: Hogs for Hospice. 

Low light situations like this require much higher ISO settings.  ISO 1600 was used for this shot.
This outdoor portrait was shot at ISO 200 and was the lowest option for this camera (Nikon D300s).

It was captured in the middle of the afternoon. I placed my son and daughter in the shade of the building behind them to have a softer light.


…it needs input. That input is the available light from your scene. The light that reaches your sensor is controlled by two things

  • Your lens + aperture
  • The shutter speed


Your lens funnels the light to your camera body. But, before it reaches the body, it filters through an Aperture (hole in your lens). Then, before reaching your sensor, a shutter has to open to allow the light in.


…your sensor needs to output (record) that information to a media card. This step saves the data the sensor collected and captures your photo.

But, different ISO ratings will alter your final image. Or the brightness of it.

So, how does it make your image brighter or darker if electronics are not sensitive to light? Great question…

The ISO setting you choose will amplify the light during output. The higher the ISO setting, the more the light is amplified. Or the brighter the image becomes.

So if you’re shooting in a low light situation, you can “amplify” the light (during output) with a higher ISO setting.

“Note: In the music and video world, this is known as "gain"... when increasing ISO.”

So adding gain or using a higher ISO doesn’t actually make the camera sensor more sensitive since it’s applied to the output and not the input.

So why the big fuss about accurate and technical information? Is it going to make you a better photographer?

Absolutely not.

But if you’re an avid music fan, a musician or videographer, then you’re probably already aware of gain. And how it can impact ISO.

Now For The Rest Of Us

All you need to know is the following...

...increasing the ISO will increase the brightness of the light due to being amplified.

Another ISO Advantage Over Film

In the digital world, we are not limited to just 6 ISO’s (100 – 3200).

In fact, a Nikon Z6 has an ISO range of 50 – 51,200!! It even goes higher if you take into account the ability to adjust the EV (exposure value)… all the way up to an ISO equivalent of 204,800!

Oh, and there’s even more. As you manually dial in the ISO, there are smaller increments…

…for example; most digital cameras have the following ISO increments… 100, 125, 160, 200, 250, 320, 400…

These are ⅓, or ½ step increases vs. doubling or halving.

The downside is calculating the settings for aperture or shutter speeds to capture a balanced exposure. It’s easier to figure out if you double or halve the ISO. To compensate, you’ll just double or halve the shutter speed or the aperture.

Cue the calculator. Not!

Luckily, we have a built-in LCD screen to see if our images are over or underexposed. By learning to read the histogram, to capture a balanced exposure, you’ll always be able to nail the exposure in-camera.

If your image is overexposed, drop the ISO to a smaller number. And the opposite if it’s underexposed.

But, you could be there all day until you get it just right. That is, if you’re starting with an ISO, that’s too far from what’s needed.

Coming up, I’ll share some general guidelines on what ISO setting to use in different lighting situations.

Photo provided by one of our students: Michael Shepherd.

This image was the highest rated photo for the month of February, in our Facebook group.

Did you bring me food?“One of my favorite photos in 2020 so far, this juvenile Giraffe at the Gulf Breeze (FL USA) zoo loves to eat lettuce out of your hand.

The challenge In photographing such a tall subject is how to balance a bright sky background with the need to get good details on the subject.

I exposed for the Giraffe, blew out the sky and with careful masking in post processing, added back a subtle sky.” Michael Shepherd

Nikon D-850 | Nikkor 24-85 | F11 | 1/125 | ISO 250.
Shot at ISO 100.  No grain or digital noise at this ISO setting. 

Please note: image is not sharp due to cropping.
Shot at ISO 1600.  Click to enlarge.  Notice the colored specks and “grit.” 

Thats the outcome to using a high ISO.  Higher ISO also contributes to a softer (less sharp) image.

So Far, ISO Sounds Like the Perfect Camera Setting. Or Is It?

Although ISO sounds like the perfect camera setting, to achieve your creative vision, it does have one major drawback.

The higher the ISO number you use, the more degraded your image will be. This degradation comes in the form of what is known as the dreaded “Digital Noise.”

Digital noise comes from “amplifying” the light. This “noise” looks like tiny colored pixels in your image.

The first image was shot at an ISO of 100. The second at an ISO of 1600. Notice how the second image looks grittier? That grit is “digital noise.” 


Film: With film, the faster (or higher) the ISO, the grainier the image becomes. The grainer the photo the more degraded it becomes.

Click to enlarge. Shot at ISO 800. Noise reduction was possible via Lightroom Classic.

Careful though. Too much reduction results in un-natural skin. Doing so creates very smooth looking skin—almost porcelain-like.

Here Is Some Good News About Digital Noise

The advancement of technology continues to lower the amount of digital noise created at higher ISO’s.

My first digital camera, a Fuji S2 (in 2002), provided decent photos at ISO 800. Anything faster was useless.

Today, my Nikon Z6 provides me with images I’m happy with at 3200 ISO! That’s a considerable improvement.

Someday, we may not even have to worry about digital noise. Until then, it’s always best to figure out how to shoot at the lowest (acceptable) ISO possible.  And how to remove noise in post-processing.

Exposure Triangle. Click to enlarge.

Is ISO Part of The Exposure Equation?

Yes. Yes, it is! Some photographers say it isn’t. Let me explain why it is…

Exposure is how bright or how dark your image is. Both the aperture and shutter speed can be adjusted to determine the exposure. Plus, the ISO can be adjusted for changing the exposure as well!

As you learned earlier, if you go from ISO 800 to ISO 1600, you need half as much light.

But, let’s say you keep your Aperture and Shutter Speed settings the same and shoot at ISO 1600. 

Guess what? 

The higher ISO is going to amplify the light by (roughly) twice as much. Therefore, your “exposure” is being affected!

In fact, your image is now overexposed. So, ISO does have a direct relation to your exposure.

To “see” this, we can refer to what is known as the Exposure Triangle. On each side, we have one element of the exposure equation: aperture, shutter speed, and ISO.

“On a side note: I believe the Exposure Triangle is outdated and flawed.”

Your exposure will be brighter with a higher ISO number, slower shutter speed and/or larger  aperture. As pictured in the exposure triangle (above).

If you increase the ISO from 100 to 200, then to get the proper exposure, you will need to set a faster shutter speed and/or a smaller aperture.

So, how do you know which exposure setting to select first?

It depends on the available light, whether or not you can manipulate the light and your creative vision for the shot.

That’s a lot to consider.

For now, let’s look at some general guidelines for choosing a specific ISO setting.

Photo provided by one of our students: David Starr.

  Shot at ISO 100  |  1/6o  |  135mm

ISO Real-World Examples

Following, you’ll find some general guidelines, depending on the lighting situation, for setting your ISO.

“Keep in mind that there are other factors that will play a role in determining your ISO.

For example, your Shutter Speed and Aperture. If you require a high ISO, due to the low intensity of light, you can choose a lower ISO if you use a slower Shutter Speed. And/or by using a larger Aperture (like 2.8 or 1.4).”

Photos During Sunset

At sunset, the intensity of the light begins to fade. The lower to the horizon, the faster the intensity of the light will fade.

Typically, I’ll start with an ISO of around 200 – 400 (depending on the lens, creative settings selected, and intensity of the light). As the intensity fades I’ll increase the ISO accordingly.

Once I reach an ISO of 800, I’ll try and keep it there by shooting with a slower shutter speed and/or larger aperture.  

Keep in mind there are other factors that will determine the ISO: 

Shot on a cold, wintery day.  Captured with a Nikon Z6  | 50mm  |  f/8  |  1/200  |  ISO 100

Plenty of sunlight left at this time of day to shoot at ISO 100.  However, as the sun dropped, I had to raise the ISO.

Although, I could have used a larger aperture and/or slower shutter speed too.
I captured this image at the Silver Lake Sand Dunes, Michigan. 

Nikon D300s  | 12-24mm  |  f/9  |  1/500  |  ISO 200

Photography on a Sunny Day

On sunny days, the light is pretty intense. However, the intensity can change throughout the day, even if it’s sunny all day.

You’ll find the sun to be brightest (most intense) at high noon. Before and after, the light is not as intense. Keep this in mind when shooting outdoors on a sunny day.

So, in general, you can shoot at a very low ISO. Like, 100 or 200. Earlier or later in the day, you may need to start shooting at ISO 400+.

Photography on a Cloudy Day

Shooting on cloudy days lowers the intensity of the light. This results in the need to use a higher ISO.

Typically, ISO 400+ is ideal…

…unless, of course, you use a slower Shutter Speed and/or larger Aperture.

Captured this portrait, of our daughter, on a partly cloudy day.  I waited for the clouds to hide the sun. 

This way I could take advantage of the softer light.  ISO 200 was needed to go along with my other desired settings: f/1.4 + 1/320.
A window lit portrait shot at an ISO of 400.

Indoor Photography

Indoors is a bit trickier. The general rule is, the more intense the light, the lower the ISO you can use.

At home, on a bright sunny day, with lots of windows, you could probably use lower ISO settings. Maybe 200 – 400 would be an excellent place to start.

At home, on a cloudy day, may require a starting ISO of 400+.

At home, at night, with a few lights on will probably require starting at ISO 800+.

Night Photography

Night photography is always going to require a very high ISO. 

Possibly 1600 or higher. 

This can change based on your chosen Shutter Speed and Aperture.

A happenstance shot ~ "Night Tree"

"While photographing a Christmas lighting display at a local lake, I walked near a tree and looked up.

Leaning up against another tree, I braced my camera, stopped down and held as still as possible.

It was pretty in color, but black and white conversion makes it even more dramatic."

Nikon D-850, f3.8, 1/10 sec ISO 8500.

Michael Shepherd
Another photo provided by Michael Shepherd.

Real-World ISO Challenges

The following ISO challenges include three everyday lighting situations you may find yourself in during a photo shoot. 

The challenges will also examine how ISO can affect the selection process for the shutter speed and aperture. Plus, why I may choose specific settings based on my creative vision for the shot.

But first, let’s examine how I approach taking photos before I click the shutter release button.

Family day at a Monster Truck event.  This event was located at an indoor arena in Detroit, MI.

This type of lighting always requires a high ISO.  Unless, of course, you’re able to add more light.  But, it wasn’t happening for this event.

Final settings:

Nikon D300s  |  70-200  |  f/4  |  1/250  |  ISO 1600

On “family days”, I tend to forget about being “creative” and just want to capture the moment. Often times I’ll switch “gears” and will put the camera in one of the “auto” modes.  No pun intended… yes, it was!

The following settings would have given me the same exposure and less work to “fix-it” in Lightroom…

f/2.8  |  1/500  |  ISO 1600

What Camera Settings Should You Select First?

When it comes to setting your ISO, aperture, and shutter speed, you have a lot to consider.

Like, your vision for the shot: 


Plus, you have to consider how much light is available.

Are you able to control the amount of light by restricting or adding?

Personally, I like to always start with the camera setting that is going to give me the creative option I want. 

So, I’ll either set my shutter speed or aperture first. Then, I’ll adjust the other two camera settings to achieve the desired result.

It’s not always that easy, though. Sometimes, I may end up using a setting I’d prefer not to use. Like, a high ISO of 800+.

Or if I’m shooting on a sunny day, I’ll set the ISO to 100 to start. 

Or I could take the easy way out and let my camera make the creative decisions for me. Which would be to put the camera in “auto” mode.

But, if you want creative control over your image, you’ll need to think through what it is you’re trying to achieve.

So, let’s look at how I approach capturing images and how I determine the camera settings for a particular situation.

Click to enlarge.  Not your typical wedding photo!

Final settings:

Nikon D300  |  12-24  |  f/4  |  1/100  |  ISO 1600

Pop-Quiz:  If I used an Aperture of f/8, instead of f/4, what ISO setting would be required for the same exposure?

Post your answer in the comments below before looking at the correct answer.

ISO Challenge 1

For this image, the couple is stationary, and the lighting, although bright, was not that intense.

I had two creative goals in mind for this shot:

One, make sure the surroundings were still recognizable when using a slightly shallow depth of field.

Two, ensure the shot was sharp by avoiding camera-shake.

Due to the lighting situation, I knew a relatively large ISO would be required. So, I started with ISO 800.

Next, I decided on the shutter speed since it was essential to avoid a blurry image. A rule of thumb is to use a shutter speed of at least the size of your lenses focal length. And then double it if possible.

For example, for this image, I was using a 12-24. The longest focal length was 24mm. Therefore, a shutter speed of at least 1/30 of a second would be required. 

Although possible, I had a few things going against me.

  • it was cold… middle of November in Michigan cold (shivering cold)
  • legs were weak due to working 8 hours up to this point

In this case, I quadrupled  the focal length for a minimum shutter speed of 1/100th of a sec.

That left me with a decision on the aperture. 

Due to the lens, the largest opening (aperture) I could use was f/4. I would have preferred 2.8. 

However, because I needed to shoot at a focal length of 14mm (to get this composition), I didn’t have a choice.

So, f/4 it is!

Before setting up the couple, I take a test shot, and… this gives me an image that is underexposed!

Now What?

To fix an underexposed image requires allowing more light to pass through to the sensor or by amplifying the existing light.

Since I was already at my minimum shutter speed AND largest aperture setting, I only had one choice… increase the ISO (amplify the light).

Luckily, the initial settings were underexposed by 1 stop. By increasing the ISO by 1 stop, I now had a well-balanced exposure with an ISO of… 1600!

Doesn’t he look thrilled!

Final settings:

Nikon D300s  |  85  |  f/1.4  |  1/4000  |  ISO 200

Pop-Quiz: If I used the following 2 settings instead, what ISO setting would I need for the same exposure:  f/2.8 and 1/8000.

Post your answer in the comments below before looking at the correct answer.

ISO Challenge 2

The following day it snows. It’s partly cloudy, and I decide to take some portraits of our son.

My creative vision for this shot is to blur out the background to add separation. And again, ensure the image isn’t blurry due to shivering!

For simplicities sake, let’s say my camera settings are the same as the night before: ISO 1600, f/4, and 1/100th of a sec.

This time I’m using a longer focal length: 85mm. My minimum shutter speed should be 1/200th of a sec.

To blur out the background, I want to use the largest aperture possible. For this lens, it’s 1.4.

Now, to figure out the ISO. 

Ideally, the lowest ISO is preferable for the least amount of digital noise. I’m using my Nikon D300s for this shot, and the smallest ISO is 200.

Final settings for test shot: f/1.4 | 1/200 | ISO 200

Result = extremely overexposed!

The camera settings are allowing too much light to reach the sensor. Although it’s a cloudy day, the light is still very intense (bright).

Now What?

I’ll need to cut down on the amount of light reaching the sensor since it’s overexposed.

Which of the three settings should I adjust to reduce the amount of light being captured?

  1. If I increase the ISO, it’s only going to amplify the light and create an even more overexposed image.
  2. Cutting the size of the opening (aperture) down to something smaller could do the trick. However, the increase in depth of field means the background will come into focus.
  3. Based on my creative vision, my only option is to increase the shutter speed. Which is fine since I need to reduce camera-shake.

The question is, how much should I increase the shutter speed?

Use your camera’s built-in light meter to help you decide!

While looking through the viewfinder, I adjusted the shutter speed dial until I had a well-balanced exposure (per the light meter).

The final shutter speed = 1/4000th of a sec!  This means the initial exposure was 4 stops overexposed.

Keep this in mind: when you change 1 of the 3 exposure camera settings, you may have to change one or both of the other two to get the proper exposure.

Which one (s) you adjust depends on your creative vision for the shot.

Isn’t she cute!

Final settings:

Fuji S2  |  85  |  f/1.8  |  1/500  |  ISO 800

Pop-Quiz: For this image, ISO 800 was not necessary!  What camera settings could I have used to lower the ISO?

Post your answer in the comments below before looking at the correct answer.

Scenario 3

The weather outside was too frightful! So, it’s time to take our photo sessions inside. Next up, our daughter hamming it up for the camera.

Her play area is situated by a big window that lights up the room. For this photo, I’d prefer natural light vs. any tungsten light. I proceed to turn off the lamps and overhead lighting.

I also want to “freeze” the action. Although she isn’t that fast at this stage, I’d prefer a sharp image.

Another thing I’d like to do is use a relatively shallow depth of field and focus on her face.

Due to the low level of light, I’ll need to use a high ISO. But, I also want to ensure that there’s not a lot of digital noise either.

So, let’s start with ISO 800. Plus, I’m using an 85mm (1.4) lens and decide on f/1.8 for the aperture.

Now, I need to select the shutter speed. Focal length times two gives me a shutter speed of 1/250th of a second.

The test shot showed that the image was overexposed. According to the light meter, it was overexposed by 1 stop.

Changing the shutter speed to 1/500th of a second, provided the desired exposure.

Tree Bark ISO 200
Tree Bark.  I love capturing the textures of nature!

Final settings:

Nikon D500  |  60 Macro  |  f/8  |  1/125  |  ISO 200

What's Next?

Understanding the relationship between ISO, aperture, and shutter speed are crucial for two reasons:

  1. It will allow you to take creative control back from your camera and shoot manually
  2. It ensures you’ll nail the exposure in-camera and won’t have to fix it in editing software

But it’s going to take time + practice. Then, practice some more.

When it comes to selecting your ISO try using the lowest possible setting according to the lighting situation and your creative vision…

  • Low-light – sunrise, sunset, stadium lights, and indoors will require a high ISO. Maybe 800+.
  • Mid-range – cloudy days or under the shade of a tree. Roughly 400 – 800.
  • Intense light – sunny, studio lights, etc. Start at the lowest ISO available on your camera. 100 or 200.

Next, you may want to check out…

What is Aperture in photography?
What is ISO in photography?
What is Shutter Speed in photography?
What is White Balance?

If you have any questions about ISO, please post your comments below. Oh, and don’t forget to do the Pop-Quiz!

Thanks for reading and have an awesome day!

A 30-year photography pro with a desire to help you achieve your creative vision! Facebook | Youtube
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Hello! My name is Chris Parker and I run this place. But, more importantly, what’s in it for you? Well, my passion is to help you achieve your creative vision.

With 30 years experience I believe I can help you do just that. So, if you’re ready… let’s do it!


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Lightroom For Beginners Guide

6 Responses

  1. The wedding: The aperture was stopped down 2 full stops so the ISO would be 6400..
    Your son: The aperture was stopped down 2 stops and Shutter speed increased 1 full stop for a total of 3 stops. ISO would be 1600
    Your daughter: You could have left the shutter speed at 1/250 and changed your ISO to 400

    1. Hey Mateusz, Yes, you are correct on all three.

      However, for my daughter, I could have lowered the ISO to 400 and left the shutter speed at 1/250s. 1/125th of a sec increases the chances for a blurry photo. Although, ISO 200 would have resulted in less digital noise. But, you probably already know this. 🙂

  2. Great article! Here are some practices of mine regarding ISO:

    1. When shooting in a studio, using lighting, shoot full manual with fixed ISO (as low as possible to keep the image noise-free).

    2. When shooting wildlife, I shoot in full manual, selecting my f-stop and shutter speed, but use Auto-ISO. The shutter speed is the most important of these since I want to avoid motion blur, and for very near or large subjects, I want to control the DOF. So Auto-ISO is the wildcard – I let it go to what it needs to in order to assure the results (good exposure) dependent on the first two values.

    3. When using flash (off-camera), when there is little light and your aperture is as wide as it can be, your shutter speed is as slow as it should go, but your flash is not powerful enough, you can raise your ISO to boost the total exposure.

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