If you plan on using your camera in the manual mode, or just want to understand how your images are created, you’ll come across the term ISO sooner or later. It’s the third most important feature related to light that you should read about (and practice later) before feeling confident to shoot in any situation.
Once you’ve read both tutorials above (they’re all related to each other and light), feel free to continue. It’ll be much easier for you to grasp all of this if you fully understand how your camera sees the light.
What Is ISO Sensitivity?
By now you should know that there are 2 ways to let in more light into your camera:
- Increase the shutter speed length
- Bigger aperture size
But what if your shutter speed is already so long that your shots are blurred (1/30 for example), and your aperture can’t get any bigger than it is (let’s say f/4). That’s where the ISO setting comes in!
When you raise your ISO speed, your sensor becomes more sensitive to light, thus makes your final shots come out brighter (and often noisier, but we’ll get to that later).
- The higher the ISO speed, the more sensitive to light your sensor is
- The lower the ISO speed, the less sensitive to light your sensor is
ISO Speed List:
- ISO 50
- ISO 100
- ISO 200
- ISO 400
- ISO 800
- ISO 1,600
- ISO 3,200
- ISO 6,400
- ISO 12,800
- ISO 25,600
- ISO 51,200
- ISO 102,400
The larger the value, the higher the sensors’ sensitivity is. Depending on your camera, you might also see some third-stops in between (like ISO 320), but these above are full stops, meaning that every higher value is exactly twice as sensitive to light as the previous one.
That means ISO 800 is twice as sensitive as ISO 400, and four times more than ISO 200. A couple of years ago most cameras had maximum ISO 3,200, whereas today even beginner models can have 12,800 (look at Nikon D3300 and Canon Rebel SL1).
When photographing fast subjects, you want a fast shutter speed. Since it was a bright day and a lot of snow reflecting the light, the photographer could easily keep ISO 100, open the aperture to f/2.8, and still get a blazingly fast speed of 1/2000 to freeze the horse.
ISO: Image Quality & Noise
As with many other settings in photography, every positive change brings something bad. In our case, it’s related to image quality. When you raise your ISO speed, your images contain more noise, and often have worse image quality (lack of contrast, less vibrant colors, colored noise).
Some cameras handle noise better than others. The more you’ll pay, the better it will perform at high ISO levels, and if you look at the ISO 4000 example above it looks clean and vibrant. It was taken with Nikon D4, a professional DSLR. Entry level cameras are getting better and better, while phones and P&S’s are horrible at it. My old Canon Rebel was horrible at ISO 1,600!
There’s not much you can do about noise, as it appears due to the fact that your sensor gets warmer when you crank up that ISO speed (1,600 and higher). Don’t worry, it’s not harmful for your camera, and you can always reduce some of it by using your camera’s built-in noise reduction feature, or a dedicated noise removal software.
One of the best things you could is buy a lens that is more appropriate for low light:
When & How To Use It
ISO 500 is still on the low end, but it was just enough to allow the photographer to use a shutter speed of 1/1000 (necessary to freeze these quick hummingbirds).
With cheaper cameras, you have to go to the menu in order to change the ISO, while more expensive models have a dedicated button for ISO control (Nikon D7100)
Stick to low ISO speeds (100 – 800) when you’re outside, or have plenty of light to work with. Use these values when you want high quality images with rich colors and no noise. Try changing your aperture and shutter speed before selecting higher ISO numbers!
High ISO (800+)
- Concerts – You’re usually not allowed to use a flash
- Indoors – Whether it’s sports, weddings or a birthday party, you might even have to use 12,800 sometimes
- Night/Street Life – Capturing movement at night is hard, and if you decide you don’t want any noise (some people like it in this type of photography), raise the ISO!
If you own a more expensive camera, it’s usually recommended to choose ISO manually. However, a lot of cameras allow you to select the minimum and maximum ISO value that can be selected automatically, so you at least have some control over it.
Now that you know more about this, it’s time to turn on your camera and test it at various ISO speeds to see how much noise you’re okay with. It’s always better to capture a noisy shot, than nothing at all!