Getting Beyond Auto - ISO
Hello and welcome to the third and final installment in the “Getting Beyond Auto” series on my blog. This is a series of articles to help amateur photographers make the best of their cameras, without investing too much time or energy. This series explores, in layman’s terms, several key concepts that will turn your pictures from “just capturing a moment” shots to “I decided to hang this in the living room” shots. This group of concepts is commonly known as the “Exposure Triangle”. Our first two posts in the series explored aperture and shutter speed, two settings that allow you to adjust how light or dark, blurry or focused, your photos will turn out. If you haven’t read those yet, I suggest you go back and read them now:
Done? Great. Now, let’s dig in to the final setting in our series, ISO.
What is ISO?
ISO is a setting on your camera that causes your photo to be brighter or darker. Essentially, it is like a sensitivity dial for your camera's sensor. A higher ISO number will mean a brighter photo. Want to take nighttime photos on a camping trip? Increase your ISO.
“But wait”, you might be saying to yourself, “didn’t we already learn how to brighten or darken a photo using aperture and shutter speed?” The answer is yes. All three of these settings can influence the brightness or darkness or your photo. Together, they give you flexibility. For instance, you could use a longer shutter speed for a brighter photo. But if your subject is moving, you’ll want a shorter shutter speed so that your photo does not turn out blurry. In this case, a good option would be to increase your ISO. That said, ISO can be tricky. If you increase it too much, your photo could appear grainy. This is known as digital noise. So sometimes it is better to start by adjusting your aperture and shutter speed, and only resort to changing your ISO when those don’t do the trick.
How is ISO measured?
Of the three settings we’ve explored in this series, ISO is the simplest to measure. The higher the number, the brighter your photo. ISO values in most cameras range from ISO 50 or 100 to some really high number that isn't realistic. The math is fairly easy with this one, unlike the others! The lowest ISO that your camera offers, usually 50 or 100, is called the “Base ISO”. That will result in the highest quality photo with the least digital noise. Each time you double the ISO, you double the sensitivity of the camera's sensor. There is a point, though, where there is so much grain and digital noise from turning that sensor up too high, and at that point the photo looks terrible. Camera companies know that people are looking for great low light capability, so they often publish very exaggerated ISO numbers. You will have to test your own camera to see how high you can push the ISO while maintaining a nice quality photo. As a general rule, more expensive cameras will tolerate higher ISO numbers. Also a very good generalization: newer cameras have better low light capabilities than older ones.
What if I’m shooting in a dark place, but want a clear photo?
Returning to the example we discussed above, if you are shooting in a dark place, but want a clear photo, decreasing your shutter speed is probably not your best bet – you would want to increase your ISO. But, you also don’t want your photo to have a lot of digital noise. Some cameras offer a “noise reduction” setting that, when turned on for certain ISO’s, will clear out some of the grainy parts of your photo. That said, noise reduction will also cause you to lose some detail. One way around this is to learn how to apply noise reduction only to the darker parts of your photos. You can do this in editing programs like Photoshop, using a technique called masking. I won’t go into that right now, but if you are interested, get in touch, and I’d be happy to refer you to additional resources.
I should also note that newer, more expensive cameras have made significant improvements in reducing digital noise in high ISO settings. These cameras include the Canon 5D Mark IV, Nikon D850, and the Sony a7 and a9, to name a few.
How to change your ISO, and Auto ISO
The specific way to adjust your ISO will vary by camera, but there are several common ways. First, enter the mode in your camera that allows you to adjust the ISO yourself. Remember Shutter Priority and Aperture Priority mode? You can also enter Manual mode. In more basic model cameras, you will need to enter the menu, find the ISO selection, and then adjust. Higher end cameras might have an ISO button on the camera that you can access without entering a menu selection. Finally, your camera might have a wheel that adjusts the ISO.
Finally, many cameras have an Auto ISO model, which allows you to set your aperture and shutter speed – now that you know how to do that – but automatically adjusts your ISO. Moreover, in this setting you can set your maximum acceptable ISO. This is particularly helpful in darker environments, because your ISO will increase to produce a brighter photo, while limiting the amount of digital noise.
That’s a wrap!
And that brings our series to a close. I hope that these posts have provided you, the amateur photographer aspiring to take better photos, with a straightforward, basic understanding of some key concepts in photography. I hope you’ll use this series as a guide to experiment with your camera’s settings, and most importantly, that you’ll have fun with it! If any questions came up and you’d like to get in touch, please do let me know[RW3] . Until next time…
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