What is ISO and the correct settings? (What others don’t mention)

what is iso

The question of “what is ISO” is a very common question among beginners. Believe it or not, many intermediate photographers and videographers  haven’t quite grasped the importance of knowing what ISO is, and more importantly, how it affects their work. 

But do not worry, by the end of this article you will understand what  ISO is, how to effectively change the ISO settings themselves, and the pros and cons of using ISO. Be sure to read everything and at the end I’ll go over what others really don’t talk about. So let’s get to it. ‚Äč

What does ISO mean and what does it do?

ISO is one of the three main pillars of photography and videography. The acronym ISO stands for “International Organization For Standardization” which doesn’t mean much to most people – but on the most basic level ISO will brighten or darken your image.

To support that, if you increase the ISO value, the camera sensor absorbs light through the lens and amplifies that light digitally to give you a brighter image. The same can be said about lowering the ISO. If your ISO setting is higher than base value  (either 100 or 200 depending on the camera), and you lower the ISO value, the sensor itself will still capture the same amount of light but will not enhance that light digitally – ultimately making it darker.  It is recommended to save the image above for your future reference. 

Now that you have a rough idea about what ISO actually is, we are going to move into learning how to change that setting.

What is ISO and the correct Settings_

How to change the ISO setting (on any camera)

I would like to say that every camera is slightly different especially considering different manufacturers. But rest assured, every DSLR  or mirror less camera has an ISO setting that is easily changed. Let’s go over the settings on a Canon camera.

To start out you do not want your camera in automatic mode. Automatic mode is one of the worst settings to use in most situations.

The first thing you were going to want to do is put your camera in manual mode, portrait mode, or aperture mode.  I would highly recommend getting use to manual mode which gives you the freedom of adjusting everything such as ISO shutter speed an aperture. (Shown In Images)

Lower-end cameras such as the rebel T6 (which does not have a touch screen), requires that you go into the settings in the menus to adjust ISO.  While medium to higher tier cameras have a button that you can press and adjust ISO on the Fly. Images of the steps can be found below this text.

what is iso

Rebel T6 Menu.  Push the “Q” button to select ISO.

what is iso

Manual Mode Canon 80D

what is iso

Manual Mode Canon Rebel T6

what is iso

ISO button and adjustment on Canon 80D.  Push button and use scroll wheel to adjust.

 ISO values and  how they affect your image

what is iso

Image taken under low tungsten light. Taken on Canon 80D with 24mm Lens.  Noise Increases as ISO increases.  Click image to enlarge. 

The basic math of ISO is double its original value. For example, let’s take a base value of 100. The next value possible would be 200. The next value possible after that would be 400, then 800, then 1600 and so-on. Below are the common ISO values found on most cameras today. I also included higher values than normal  which are found mainly on high ISO cameras/mirrorless cameras.

  • 100
  • 200
  • 400
  • 800
  • 1600
  • 3200
  • 6400
  • 12800
  • 25600
  • 51200 (mirrorless & some DSLR)
  • 102400 (mirrorless)

So how do higher values affect your image? Simply put it adds digital noise to your image. As seen in the photo to the right, the higher the iso value the noisier your image becomes. You should know that slight noise on a photo will not affect the final result that much. But values above 1600 ISO can affect the overall result of your image in a negative way. Rest assured many programs such as Adobe Photoshop or Gimp have tools that reduce or eliminate noise all together (depending on the severity) – but I have to  mention that digital noise in video can be irreversible. So keep that in mind. I will explain later in this article about what setting to use while shooting video to eliminate that digital noise, so continue reading!

what is iso

An Apple Photographed @ 800 ISO and 3200 ISO.  24mm Canon Macro Lens.

Benefits of ISO

The benefits of ISO can be great in certain situations. What it can allow you to do is brighten the image and increase shutter speed ( I will have an article soon diving deep into shutter speed). This will allow you to take photos of very fast-moving objects while keeping them in focus.

 You can also benefit in low-light situations.  For example, if you were in any low-light situation and you increase the ISO, you can get a much better image than not increasing it at all.

But keeping in mind that the higher your ISO is increased, more digital noise will result.

When to use higher ISO

Like stated in the previous paragraph, you should use higher ISO values when you are in low-light situations. Digital amplification of light can drastically improve a low light situation.  Here are a few situations that would warrant the need and benefit of using higher values:

  • Indoor low-light situations
  • Night photography
  • Fast moving objects that require you to increase shutter speed

It is highly recommended only to use higher ISO values when absolutely needed. Your ultimate goal is capturing the most high-quality images. The higher your ISO value the lower the quality of your image; so use it sparingly.

When to use lower ISO values

So when should you use lower ISO values?  The answer to that is extremely simple, whenever possible. It should be your ultimate goal to use the lowest ISO setting on your camera.

Now we all know that every situation is different and requires different settings but that should be at the forefront of your mind when composing your photographs. If this means lighting your subject better or moving to a totally different environment, do that instead. There isn’t worse feeling than bringing your memory card home and uploading that image onto your laptop or desktop; and noticing that all of your images are noisy but looked fine on the screen of your camera.  Believe me that has happened to me quite a few times and it’s something that I strive to never repeat.

You should also know, like stated before, not every situation is the same. You may want to  capture a fast-moving object which requires higher shutter speed which will darken your image which you will then have to use ISO to brighten. Or you may attempt to avoid higher ISO in low-light situations by decreasing shutter speed. While this is great, if the camera is not on a tripod you will notice motion blur.  There is a trade-off for everything in the photography and videography world. It’s just something we all have gotten used to. Don’t worry, you’ll get used to it as well!!!  

Here are a few situations where you would not need ISO:

ISO photography

This image was taken at base ISO of 200.  Nags Head, NC. Click to Enlarge

ISO photography

This image was taken at base ISO of 200.  Nags Head, NC. Click To Enlarge 

  • Outdoor landscape photography (during the day)
  • Bright mid-day sun
  • Well lit subjects (such as product or portrait photography)

The difference between video and photography

While the idea in principles of ISO in video remain the same in photography; the way that you use it in video is quite a bit different.  Let me explain…

The noise that’s obtained in video is nearly irreversible. If you decide later on you want to attempt to fix the noise, and while there are tools to fix it,  your rendering times on the videos will increase significantly. Also, the programs are not perfect at eliminating noise completely.  

Shutter speed in video is incredibly important. The speed of your shutter should remain constant depending on the frame rate of your video. So, you are not able to darken or lighten the video with your shutter. Your ISO and aperture control  brightness and darkness.

Adjusting ISO in one area can affect the brightness in the next area. For example, if you are in a room that is lit perfectly for your ISO settings and you move into the next room that isn’t, you constantly have to change your settings. In terms of video, ISO monitoring is incredibly important and (as in photography), keeping the ISO as low as possible is the number one priority.Many beginners and even intermediate videographers have a very hard time determining what ISO level to use especially indoors.  Side Note: It is highly recommended to use a lens with a very low aperture to avoid using higher ISO values to get a brighter image. The standard for the low aperture value is 2.8. The ideal aperture value for indoor videography is between 1.8 and 1.4.

Pros and Cons

What I will do for you now is lay out a nice pros and cons list in terms of  low ISO values vs. high ISO values. If anything you should get the most value out of this pros and cons chart.



  • Brighten image at higher shutter speeds
  • Brighten low light situations
  • Some cameras handle ISO great (Sony)
  • Sometimes it’s absolutely needed


  • Causes digital noise on image
  • Digital noise caused can be irreversible
  • A higher ISO in video can cause blown out highlights in one area rather than the other

What are others not mentioning?

Now that you understand what ISO does; what I’m about to mention will make a lot more sense.

The severity of digital noise caused by ISO depends on your sensor size. 

I do not want to go into too much detail and confuse you. A full frame sensor in the same environment in conditions, and same ISO setting, will ultimately have less noise then a smaller sensor (such as an aps-c sensor). Just know, the trade-off for a full frame camera  to an aps-c camera is price. A full frame camera such as the 5D Mark IV is more expensive  then an aps-c camera such as the Canon 80d.

A video that explains what ISO is…

For those of you who are visual learners, I am embedding this great video that ties in everything we discussed here today.  The gentleman in this video answers your question of what is ISO perfectly.  Give it a watch if you are still a bit confused.

To conclude…

Our recommendation for you is to obviously strive to keep your ISO at base level; ultimately avoiding noise upon your images and or video.

It is said in today’s day and age that noise within photos and video can hardly be seen because many of which is viewed on a cell phone. While this is true, we as photographers and videographers strive to produce the best images possible. Which is why most professionals avoid using ISO as much as possible.

If you do find yourself needing to use ISO,  attempt to use nothing more than 1600 ISO on a DSLR;  and anything below 6400 ISO on a mirrorless camera such as the Sony a7iii.

With all of the knowledge that was given to you today in this article, you should be able to go out and shoot great photos and video knowing what ISO can and will do for you. I really hope it closed the gap between you not knowing and being confident in your skills.

Please leave a comment below with your thoughts! Be sure to sign up  to our newsletter. We release valuable information one a week about what’s going on in the camera world.Until the next one, take care!


I have been taking photos and film since I was a child. Now that I'm in my mid 30's, I want to share with the world what I have learned over the years. I attempt to live every day to the fullest and share that with you through my blog. I am an electrician by trade and photo and video lie within the "hobby" aspect of my life at the moment. It's what I'm truly passionate about.
Back To Top