Beginner Photography Class Day 3: Understanding ISO

Over the past two days, we’ve discussed two important functions of your camera – aperture and shutter speed. These two things work together with your ISO to balance the right amount of light needed to create a well-exposed photograph.

ISO controls your camera’s sensitivity to light. When you increase your sensor’s sensitivity to light, you can let less light in and still get a good photograph.

Understanding ISO is important.

Let’s take it back to what we know…

Imagine you’re photographing a performance in a theater with low light. If a wider aperture lets in more light, but also reduces your depth of field to say one actor on a stage instead of all five actors on a stage, would you want to increase your aperture to let in more light?

And, if slowing your shutter speed down lets in more light, but then also causes blur in your photograph from camera shake because you’re now holding your 200-mm lens at a speed slower than 1/200th of a second, would you want a blurry image?

The answer, of course, is no to both of these things. And that’s where ISO comes in. Typically, in low-light situations like theaters, museums, concerts, indoor birthday parties, and family photos inside a dim house, you’ll want to increase your ISO so that you don’t have to slow your shutter or widen your aperture.

Most cameras have an Auto ISO feature that will do this for you. And I highly recommend you do 90% of your shooting, as a beginner, in Program mode with the Auto ISO feature enabled so that the camera can decide.

But, if you’re ever going to make a setting change, ISO is, in my opinion, the easiest one to make. There aren’t any fractions or numbers that mean one thing by themselves and another if they have a quote beside it. Increasing your camera’s ISO will add more light and decreasing it will add less. Simple.

That said, it, too, has a down side. The higher your ISO, the more likely you are to add digital noise to your image. Here’s today’s video lesson:


** In general, to avoid noise, use the lowest ISO possible for your camera (50-200)

** In dimly-lit places like museums, theaters, and concerts, if your images are blurring and you’re not getting enough light, try using a higher ISO like 400, 800, and 1600. Some cameras may even go as far as 6400.

** More expensive cameras do better at higher ISOs. Cheaper cameras and point-and-shoots typically introduce noise at ISOs higher than even the lowest available setting.

** Get the shot no matter what it takes. If you have to raise your ISO to get the shot but you’re worried about how it will affect the saleability of your photo, take the shot anyway. A good photo that isn’t saleable is better than a blurry photo that is neither saleable nor good.

** Ninety percent of the time, you’ll want your camera to make these decisions for you. Put your camera in Program Mode with the flash off and your ISO set to Auto. If you don’t have an Auto ISO feature or you prefer to keep your ISO at the lowest setting to ensure you don’t get any noise in your photo, remember that you might want to increase your setting in dimly-lit places. A birthday party photo shot at ISO 800 with noise, but without the harsh white light of the flash and without the blur from hand-holding, is still a birthday party photo you can be proud of.


In May 2011, we hosted a Photography Expedition in Seville, Spain with travel photographer Efrain Padro. He wrote a great article about how to photograph in low light when you don’t have a tripod. With three shots, he shows what difference changing the ISO setting on your camera can make. Check out his photos and read what he has to say on ISO, here.

I hope you’re starting to understand all of these sophisticated functions on your camera. It takes practice to be able to master them, but you’ve got to start somewhere! You’ll never sell a photo if you don’t try. So grab your camera, and get out there!

Tomorrow we’ll sum up everything you’ve learned so far with our last of four videos on how shutter speed, aperture, and ISO work together.

[Editor’s Note: Learn more about how you can turn your pictures into cash in our free online newsletter The Right Way to Travel.  Sign up here today and we’ll send you a new report, Selling Photos for Cash: A Quick-Start Guide, completely FREE.]

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