HomePhoto TipsWhat is ISO?

What is ISO?


The term ISO has been around since the early film photography days, but why is it still relevant in the digital age? ISO is one of the most important camera settings in digital photography.

You may have heard of the Exposure Triangle, which consists of Shutter Speed, Aperture, and ISO. These three work together harmoniously to create a perfectly balanced and exposed image.

What is ISO in Photography?

ISO stands for International Organization for Standardization, and it is a lot easier to understand than its name. ISO is a setting that allows you to control how bright or dark a photo is, and it is a standard telling you how sensitive your film/digital sensor is to light. The higher the ISO value is, the brighter your photos will look. Adjusting the ISO is a quick and easy way to brighten up your images when you’re shooting in dark environments. This allows a lot more flexibility when you’re working within the Exposure Triangle (aperture, shutter speed, and ISO).

ISO Setting in Film

In the photographic world, ISO is most commonly referred to as a film rating system. Think film photography, not the movies. In terms of film, ISO is used as a rating system to tell you how sensitive the film is to light, or how fast the film is.  The lower the ISO number (i.e 50), the more time the film needs to be exposed. The faster the ISO film speed, less light is required to take a picture.

What are the ISO Values?

Each camera will vary, but the ISO values can range from ISO 100 to ISO 6400. Here are the most common ISO values you’ll discover in many digital cameras: ISO 100, ISO 200, ISO 400, ISO 800, ISO 1600, ISO 3200, and ISO 6400.

Notice how each number is doubled as the ISO values increase. When you double the ISO speed, your photos will also double in brightness which means the values are relative to each other.

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ISO and Noise

Increasing the ISO to a high value can instantly brighten up your photos, but it does have its consequences. Every time you dial up the ISO value, it creates something called image noise. Film photographers will call it image grain, but the term noise is more common among digital photographers. Image noise will show up as tiny dots or “grain” on your photos and are more noticeable in darker areas of the image.

One thing to note is that digital noise is affected by the size of the pixels used in the camera sensor. Larger pixels will result in less digital noise, which is why DSLRs do a fantastic job at higher ISO values compared to a compact camera. DSLRs have a much larger sensor and pixel count.

With this in mind, it’s a good idea to keep the ISO value as low as you can and adjust the aperture or shutter speed first. Sometimes, however, lighting conditions are poor and you will have to compromise image noise for brightness. It’s all part of the joy in photography and experimentation, isn’t it?

Luckily, many cameras nowadays do an amazing job of keeping the image quality high even at a higher ISO value. Although they’re at a higher price tag, these professional cameras allow you to shoot at very high ISO without compromising quality.

What is the Best ISO?

In many situations, it is not possible to produce an image with low ISO sensitivity. Such situations include those where there is low light and no tripod, or where the motion is very quick such as in sports photography. In this scenario, you’ll want to use a high ISO.

Man photographing outside on a sunny day looking at ISO settings in the DSLR camera screen

On a sunny afternoon however, you won’t have any problems with light and can therefore lower your ISO to a much lower number. In between a sunny day outside to night time photography, you will have to experiment with the ISO values to find the right balance between exposure and image noise to find the best ISO. Here is a quick guideline of common ISO values depending on the lighting situation:

  1. Bright, sunny day outside: ISO 100 or 200
  2. Cloudy days, indoors, or window light portraits: ISO 400
  3. Indoor photography without flash: ISO 800
  4. Reserved for very low light conditions: ISO 1600

Suggestions for ISO in Various Scenarios:

  • Fireworks: ISO 100 (do not change)
  • Dusk: ISO 200 to 400
  • Stars: ISO 800 to 1600
  • Sunsets/Sunrises: ISO 200
  • Evening Parties: ISO 800
  • Stormy Weather: ISO 400

Since you want the sharpest photos possible the ISO is a setting to keep an eye on. Remember that the higher you set the ISO the lower light your camera can handle, however that higher ISO will also increase the amount of visible noise or graininess also. You want to find a balance between how dark it is and how much noise you can get away with in your photos without it ruining the shots. 

Also be sure to have a tripod available when you are going to be in low light settings to be sure to minimize the movement involved that would possibly make it grainier. You will want to do everything you can to make it sharp, even when you have to raise the ISO.

Film ISO vs Digital ISO

If you are using a film camera there is a much better chance that you are already familiar with ISO. When you choose your film you select the ISO. Digital photographers are not so constrained by a roll of film having one set ISO sensitivity, and can change the ISO sensitivity rather easily.

That isn’t to say digital cameras can escape the adverse effects of shooting with higher ISO. In film, when the ISO is too high, photos tend to appear grainy.  The same is true with Digital Cameras instead of being called grainy it’s called noise. The higher the ISO, the the more noisy digital photos appear. Whether your using film, or a digital camera, ISO speed affects the aperture and shutter speed combinations you can use.

What is Native ISO?

Native ISO, is a crucial camera setting that will help you in producing the highest image quality. When you adjust your camera to Native ISO, this is the baseline setting your camera is automatically set to for the best image quality and detail. When you go under or above the Native ISO your camera sensor will be more sensitive to the fluctuating light. This is why it’s optimal to keep your camera at Native ISO as much as possible.

What is Auto ISO?

Several years back, many cameras started introducing Auto ISO setting which allowed photographers to manage their noise balance during shooting. Turning on Auto ISO is a good idea if you’re prioritizing Shutter Speed or Aperture mode, allowing the camera to increase or decrease the ISO based on the current exposure settings. Certain cameras will even allow you to set a parameter for the Auto ISO sensitivity so it doesn’t go over the limit you set it to.

Getting a good grasp on ISO and how it functions will help you make better choices about setting up your camera, which in turn, will produce good quality shots.

How to Adjust the ISO Settings?

There are many ways to adjust the ISO depending on the type of camera you have. The following are the most common ways:

  • Get your camera out of Auto Mode. This will allow you to adjust the ISO in Shutter-Priority, Aperture-Priority, or Manual Mode.
  • Most beginner DSLRs will require you to enter the Menu mode to access the ISO. You can change the ISO value from the menu.
  • For more advanced or professional cameras, there is usually a dedicated ISO button on the camera itself. Press down on the ISO button while turning on the dial to change the ISO values. If you don’t see an ISO button, you may be able to customize it. Check your user manual for more information. 
  • Some cameras will also feature wheels where you can quickly change the ISO.

ISO Camera Setting Tips

  1. Do you hate that flashy look of photos indoors? Turn the flash off, lower your aperture and raise your ISO. You shouldn’t need a flash.
  2. Want to tell a story with your photo? Turn your aperture all the way down (lots of people refer to this as shooting wide open) and blur out some element of the photo, ie, a baby with a big sibling blurry but in the background.
  3. Shooting sports? Set shutter speed faster and your subject suddenly becomes sharp!
  4. It helps to take three or four pictures, each with different settings, so you can get a feel for how each setting will change your photo.

Debunking the ISO Myths

There are many misconceptions about ISO and how it works. Let’s take a quick look at the most common myths:

  1. ISO is related to exposure.

    Interestingly, ISO is not part of exposure. Whereas aperture and shutter speed physically capture more light into the camera sensor, ISO doesn’t do that. Instead, ISO just brightens or darkens a photo based on the captured image. This is why many photographers don’t consider ISO part of exposure.

  2. ISO is the sensor sensitivity.

    This is probably the most common myth about ISO, and it’s actually false. ISO doesn’t reduce or increase the amount of sensitivity in your camera sensor. In fact, your digital camera only has a single sensitivity. ISO simply brightens your photo based on the current exposure. It maps how bright or dark the photo will be based on the ISO values. 

man taking photo of sunset mountains with ISO 200.


Learning to control ISO is a fast way to get your images correctly exposed. It helps us control the other two parameters of the exposure (aperture and shutter speed) which all work together to create a balanced image. 

  • Higher the ISO, the more sensitive the film/sensor is to light.
  • ISO speed affects allowed aperture and shutter speed combinations.
  • Higher the ISO, the more grainy or noisy pictures may appear.

Knowing how these parameters work together and their connection to each other will help you grow as a photographer and develop your creative vision when you are out shooting with various light conditions. With enough practice, you’ll be turning the dials and adjusting your ISO settings naturally without thinking twice.

We hope this information was useful and that you’re ready to start controlling your ISO! Let us know your thoughts, comments, and experiences below about ISO.

Photography Tutorial: How to Work with ISO

ISO Explained

Understanding ISO

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  1. love the site! have a question on ISO: when I’m on manual mode I currently have ISO on auto. But having read the above I understand that the lower the ISO the better. so if I’m setting aperture and shutter speed I’m assuming that the ISO will automatically adjust to get the best exposure? which may mean the ISO goes higher than it needs. So it would be better to set this manually too?
    also when you’re in fully manual, which do you set first? aperture or shutter speed and ISO? I know it’ll differ if the subject is moving or not – if moving you want to reduce shutter speed. and then for static pictures would you always set aperture first to control the depth of field?
    so far I’ve been trying to get my head around the technical side of things, but when it actually comes to taking a photo on manual mode I feel completely at a loss!!! Are there any good starting points? I liked the guidelines for aperture dependent on how much natural light there is but not sure where you would start on shutter speed….
    Looking forward to your response

  2. This is great! I´ve heard all this concepts before but had no clue what they meant. I love it how you “tranlate” them into examples. Now I know what to do with ISO! It´s not chinese anymore. This is exactly the type of site I was looking for to learn about photography in simple words. Thanks again!

  3. Lowest is always best, but it depends on if you can use a tripod or if your subject is in motion. If they are moving and there isn’t much light you’ll have to increase the ISO. It’s kind of a last resort setting.

  4. God bless you all for all the information on this site, I’m just about to buy my first dslr and I’ve always loved photography and wanted to be a pro. I’m excited and eager to learn, I’ll update you as I get along.

  5. Just found this site…I’m a beginner myself and I really want to learn Photography and hopefully get a degree. I actually learned a lot with not so much of reading long paragraphs. I like how its straight to the point and understandable at the same time.

  6. I have a cannon 5d and am still learning. My photos have been selling well but I am concerned that they don’t have that real sharp clear look to them. Can you give me any tips. Also if the iso should be lower and it isn’t a really bright room would I just have to change other settings to let more light in instead of going higher in iso. The last practice I did was in a bedroom and the photos were very noisy.
    This is the best site I have come across by the way. IT’s fantastic for us beginners !!

  7. ISO isn’t effected by zooming but the aperture is. The more you zoom in or the longer the focal length: the less the aperture can open and that’s why you are getting darker pictures when you zoom in. After you zoom you have to re-evaluate your exposure.

  8. The lecture was great but I wanted to know if zooming has any thing to do with ISO because whenever I zoom the picture appears darker.

  9. um…
    I’m 14 and I’m still a bit of an amateur i have a Nikon D70, my dad is also a pro photographer but he doesn’t have time 2 give me photography lessons so I’m learning the hard way. I do a lot of action photography, any tips will help, also if you would like to see some of my photos and point out my flaws its on the following url:http://www.flickr.com/photos/steenkamp/ thanx 4 all u ppl who do give some tips

  10. I have had my Nikon D80 for 2 years and don’t know how to use it properly. I have now learned about ISO. Will practice tomorrow at day light. Any tip on how to get great pictures with the Nikon D80 will be appreciated. I love photography. Thanks to all who reply.

  11. Its really simple and superb. I will start my photography from today onwards with my Canon PowerShot A590 IS.

  12. Thanks,now I understand better about digital ISO.I use to take my pictures, the Nikon D50 and Nikon D80.Thanks again.

  13. Want to know more about being a professional photographer. Any useful training guide and resource will be appreciated.


  14. I love to do photography but i am little slow in english thats why sometimes I don’t understand but this time it was very easy and quick to learn photography. I tried this at my own I got wonderful pictures
    Thanks to this website who teaches a free photography course very easy and quick

  15. Your ISO really help me lot to make my photography better. Thank once again for the details you provided about the difference between Film ISO and Digital ISO.

  16. What you’re referring too is the depth of field. To get the effect you’re talking about you need a wide open Aperture. And a long focal length (Zoomed all the way in). You’ll have to use manual mode to change the settings, even then your camera may not have a long enough focal length or an open enough aperture to make the effect you’re looking for.

  17. WOW. It is nice. Straight & to point. Now I have a question, somehow I think maybe it has to do with ISO but not sure. I have a basic Nikon CoolPix S570 with wide 5x zoom & no clue what that means either lol. BUT, I want to know how to blur the background in a photograph. Maybe what the wide 5x zoom means Thanks in advance!

  18. Oh! at last i got the answer,(what is ISO?)…
    I m a beginner and very confused about ISO & Aperture.Now i get it.Thanks a lot……I also want to learn more from u…I know u help me to be a professional…

  19. Hi,
    Thanks a lot for understanding on ISO..I’m new to photography and want to learn it badly, I first thought ISO was just to improve the light factor? but never heard the term aperture before? not sure what that is, I have a Canon Rebel XT.. I was planning on buying Nikon D90(felt really comfortable with it)not sure to ask but do you favour Canon and why ?
    Kindly let me know.

  20. NOW I understand why I’m getting grainy photos in certain low-light conditions. I need to use the ISO setting! A simple discover that will make a huge difference in my low-light photos.

  21. Thank you for this wonderful lesson very straight forward and easy to understand! i’m a beginner and I’m trying to learn everything i can! congratulations to the admins for the good work!


  22. Thanks a lot, it is what we say less words more knowledge. i am beginner in photography and i am gaining a lot of information from this site. ENJOYING PHOTOGRAPHY WITH MY NOKIA N86 8MP Camera. KEEP GONING DUDE

  23. Because lower ISO provides higher quality photography it’s recommended that you use low ISO sensitivity as often as possible. High sensitivity ISO, around 1600, results in grainy photography. High Sensitivity is typically used when you want to capture very quick motion such as in Sports Photography, or when you cannot make the shutter speed any slower or open the aperture any larger in low lighting conditions.

  24. Hello,

    From the lesson I have understood what ISO is, but i still have not figured as to when one could use higher ISO’s or lower ISO’s. Could you give an example. In the sense, if you are capturing a bright object, is the ISO to be set to at a relatively high number and vice versa?

    Awaiting your response!

    Thanks in advance,


  25. If your camera is set to automatic then it will automatically update the exposure. If it’s set to manual you will have to compensate for not having a flash. It’s great that you use a tripod in such cases and I agree that a flash can ruin any great composition.

  26. Enjoyed the review on ISO. I now use a digital camera most of the time. If I set it to “No Flash” Does this force the camera to automatically increase the exposure time in a low light setting? I like to use a tripod and often do not want the glare of a flash.

  27. Your welcome. I hope you enjoy the rest of the lessons. If there’s anything you think we’re missing let us know. We’re always looking for new lesson material.

  28. This lesson sums it up just fine so that I understood it exactly with a few precise words- rather than a lot of long paragraphs. I will play around in your site more. This was my first spot on the website.

    Thanks for the information and for taking your time to post it.


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We’ll get straight to the point. To keep quality high, we work together with the best photographers in the world. As a company, we are spending a lot of money to give our writers a fair compensation. 

To stay online and become better in what we do, we depend on contributions and some products we sell. If everyone who enjoyed reading the above article gave just a little, we could keep Photographycourse.net thriving for years to come. The price of a cup of coffee is all we ask.

We know that most people will ignore this message. But if photographycourse.net is useful to you, please consider donating $2, $5, $10 or whatever you can to protect and sustain Photographycourse.net. 


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