Oh ISO, you elusive pixel pixie, what do we do with you? Do we even know what you are?
Kids, once upon a time, disposable cameras weren’t just wedding reception novelties. You actually went to the store and had dozens to choose from, for all those special occasions like birthdays and vacations and first t-ball games. And they had these numbers on them – 100, 200, 800, 1600 – and if you were 13 years old and didn’t have parents who were really into film photography (like me) you had no idea what those numbers meant and why they cost different amounts or if there was any real difference. So, you bought the camera with the highest number you could find, because 1600 HAS to be better than 100, right?
Sigh. I’d weep over my high school scrapbook, but it’s a PCS casualty and hasn’t been seen in years.
Out of the Big 3 functions we’ve explored thus far, ISO is the least-manipulated, for me. It’s pretty “set it and forget it,” and you may hardly ever need to pay much attention to it. Still, it’s important to know what it is and why it’s there.
As with all things photography, it comes back to light. ISO manipulates your camera’s sensitivity to light. If it’s a lower number, it’s less sensitive. If it’s higher, it’s more sensitive. So, yes, BIG difference between 100 and 1600.
When your camera is on Auto, ISO will usually stay very low, probably 100. This is because, if you’re outdoors, there’s lots of natural light. And if you’re indoors (or it’s night time) the Auto will engage the flash to make up for all the missing light.
However, if you go full-on Manual, you can manipulate ISO to accomplish several goals. For one, you can step up your ISO if you’re in a situation where there’s not bright, bright sunlight shining down – but you also don’t want to use (or have) a flash. For another, I do know photographers who prefer a higher ISO setting in general, because they like the effect it has on photos. Lower ISO lends to smoother pictures, high ISO to grainy/rougher pictures. Examples:
Shutter speed: 1/320 sec
Already I had a very small Aperture (remember, large numbers = small Aperture opening) and a pretty quick shutter speed to limit the insane amount of sunlight going on. ISO is on the lowest possible setting also, and so the image is very smooth, even when you zoom in or print in a large format.
Shutter speed: 1/250 sec
You might have to click this one to enlarge it, to really see what I mean. I took this right as Baby G was waking up from a nap, so the lights in her room were off. The only light source was from the hallway. I cranked the ISO WAY up so I wouldn’t have to use the flash and screw up her natural expression. Because the ISO is super-high, the picture has a rough grain to it as the camera is grasping for as much light as possible to capture the image.
Again, this may not be something you need to mess with very often, but there have definitely been times where changing the ISO has saved my pictures when my aperture and shutter speed capabilities were insufficient to the situation. Also, some people just like a grainy old-timey look to their shots. You might, too, when you play around with it.
And that’s the end of the technical part of this series. Next time, we’re going to start looking at theory. We’re going to have some Come To Jesus moments, y’all. Get ready.
Read other posts in this series:
Get More From Your Camera: Aperture
Get More From Your Camera: Shutter Speed
Get More From Your Camera: Dead Space
Get More From Your Camera: Cropping and Creating Lines