First, to give you an idea about exposure triangle, think of it as a tripod. A tripod has three legs. The legs have to be equal in length for it to stand up. If one or two is shorter or longer than the other, it would collapse and ruin your camera. Balance is important. So in essence, the exposure triangle works the same way with the pictures that we take. All elements have to be balanced so it won’t ruin your image. Okay. Let’s move on to the first.
ISO What is ISO? It’s actually the camera sensor’s sensitivity to light. “Huh?” Okay, I’ll explain what sensors are first.
In the old days, when you take a picture of something, light goes through the lens, and then, blah,blah,blah AND then, the film (for simplicity, let’s think of films like kids in a classroom)sees it and tells itself, “hmmm, nice image! It’s so nice, I’ll make a copy of it in my notebook!”. Now, with digital cameras, it goes through the lens , and then, blah,blah,blah, AND then, the sensor sees the picture and says “Wow! Awesome! I want a copy of this but I’m too lazy to write... A! Here comes memory card. I bet I can trick him to making a copy of this for me. Hehehehehe”. So basically, sensors function the same way as a films back then, except it doesn’t save your pictures because it’s like a lazy bully so he passes the task of copying to the memory card. But you shouldn’t look down on sensors... They’re a nice bunch... Their parents just raised them wrong... It’s not their fault you know. Anyway, I won’t explain what memory cards are anymore because if you don’t know what they are, then you’re an idiot.
So again, for clarity’s sake, FILM = SENSORS. Forget the part about sensors not copying the image. We’re in digital age now so things won’t exactly be the way it was before. We can’t control memory cards and they’re not a part of the exposure triangle so let’s forget about them already okay?
Films back then are rated based on their FILM SPEED. Basically, the lower the film speed is (for example 100), the less sensitive it is to the light. So it takes a bit longer for it to record the image. So think of a lower film speed like a student who writes slow in the classroom because he doesn’t have good eyesight. It takes a while before the film/student to completely copy the image because his eyes are not that good. Meanwhile, a higher film speed means it’s more sensitive to light. A fast film like an 800, is like a kid who has very good eyesight so he can write fast. Get it?
Okay. Back to ISO. ISO is the camera’s sensitivity to light. It’s basically film speed. So based from what we learned earlier, low ISO is not so sensitive to light. Higher ISO is more sensitive to light. When you look at your ISO, you see numbers like 200, 250,320, all the way up to 3200. Different models differ in these numbers. Some can go lower and higher. So read your manual.
Now if we apply it in photography, we use LOW ISO (since it is less sensitive to light) for locations with very good lighting , for example a park on a sunny day. On the other hand, we use HIGH ISO (since it is more sensitive to light) for locations with bad lighting like indoors at night.
To make it easy, here’s my formula:
Sunny day = 200
Overcast/shade = 400
Indoors/night = 800
Of course, it’s not perfect so you have to adjust it based on the available light. But it’s usually around those numbers.
Now each element of the exposure triangle has what I'd like to call a “special characteristic”. For ISO, its special characteristic is NOISE. Noise are little dots in the pictures. The higher the ISO, the more noise it has. That’s why as a rule of thumb, your ISO shouldn’t be higher than 800 because 800 has the most acceptable noise. And again, it depends on the camera. Newer models have good ISOs even if it’s set to 1600. But noise aren’t always bad. It sometimes looks good especially in “vintage look” like black and whites and sepias, etc. It gives them more character. It looks older I guess. But don’t overdo it though.
The photo below is an example of a picture with noise in it. Take a closer look at the keyboard of the laptop:
In this example, even with the noise, it's okay. Again, it depends on the mood of your picture. You wouldn't want this amount of noise on a colored picture of a baby right? So again, the rule is, avoid noise as much as possible. Little tip: It's easy to apply noise in post processing but it's hard to remove them. Well, actually, it's easy to remove noise. What I mean is, the results won't look good... Sometimes, after cleaning up a very noisy shot, your image will look like someone decided to cling wrap it. After taking a shot, review the picture in your computer. If you think that noise will give it more character, then that's the time you add noise.
So that’s it! Now it wasn’t too hard was it? Next week, I’m going to discuss Shutter Speed. After I discuss all the elements of the Exposure Triangle, I’ll teach you how to manipulate all three to help you get the image that you want to achieve. So please, be patient okay? See you next week! =)
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