So, What is ISO?

4/3/2015

What is ISO?

March Issue

So, what is ISO?

What is ISO and how do I use it?

So what is ISO? How does it affect my pictures? And how do I use it?

ISO stands for International Standards Organisation, which doesn't really mean or explain much. Basically it relates, once again, back to when people were using film in their cameras. It basically set how sensitive the film was to light. So an ISO 100 film wasn't very sensitive to light, where as an ISO 1600 film was very sensitive to light. In other words if you were using an ISO 100 film and shooting at night, the shutter would have to be open for a long period of time in order to get enough light on to the film. Where as if you had an ISO 1600 film and you were shooting at night, then you more than likely would be able to hand hold the camera. The shutter speed would be much faster because it would collect the light on to the film much faster.

So how does adjusting the ISO affect the final image? In the days of film what would happen, the larger the ISO number the more "noise" or "grain" is visible in the photos. I have put some photos below at different ISO's so you can see what I am talking about. Now in DSLRs they replicate this by adding noise to the final image.

ISO 100

ISO 400

ISO 800

ISO 1600

ISO 6400

As you can see from the images above, there is a major difference between an ISO 100 picture and an ISO 6400 picture.
These days most people are used to looking at perfectly clear photos, mainly due to phone cameras. So you probably say, why would I want a picture that is all grainy and isn't clear. In some cases it may be because you don't have a choice, like in some night photography. You don't want to use a flash because you won't be able to capture the atmosphere if you use a flash and you don't have a tripod and need to hand hold your camera. The main reason I would use an ISO that would give grain to an image is because it can provide a sense of drama or a sense of age to a picture, I find this works best in black & white photography. Below are a couple of grainy photos taken by a couple of photographers who photograph homeless people. you can imagine is these photos were crystal clear then there wouldn't be the sense of drama or roughness about the images.

By Lee Jefferies

By Kenichi Anai

So how does ISO relate to aperture and shutter speed? Well all of these are connected and when one is adjusted the other two will either automatically be adjusted or need to be manually adjusted depending on what setting you are using on your camera. Below is a diagram that will help to explain how these are connected.

As you can see the ISO, aperture and Shutter speed are in each corner of the triangle. The writing in the red indicates the consequences of adjusting any one of these. So with ISO, as explained, the higher the number the more noise or grain in the image. If you don't want grain then you can adjust the shutter speed by slowing it down. But then the slower the shutter speed the more chance there will be of motion blur. And if you don't want grain or motion blur then you can try adjusting the aperture, but then you will loose the depth of field, meaning there will be less in focus in the picture, only the item that you focus on.

So in conclusion, there are a number of ways you can manually adjust your DSLR in order to give you a different effect in your final image. So enjoy experimenting with these and try different adjustments for the same image and see what you can come up with. This is the good thing about owning a DSLR, you can experiment as much as you want and you don't waste money on film.

I hope you have enjoyed this months' topic "So, what is ISO". Please share this with any of your friends you think it may benefit.

And if you have any topics you would like me to cover in future editions of "Photography Tips" please feel free to contact me by any of the means below.

If you have any topics you would like covered, you can contact me either by commenting on my Blog which is on both www.thebooth.com.au and www.brendanfellowsphotography.com or by leaving me a message on one of my Facebook pages https://www.facebook.com/TheBoothSydney or https://www.facebook.com/brendanfellowsphotography . I look forward to hearing from you.