There are three settings that go into achieving correct exposure and here they all in all their glory:
I am going to post one lesson for each and then we'll have a lesson that puts it all together and explains how to actually shoot in manual mode. And I'm going to try and make these lessons as basic and easy to understand as I can.
Simply put, your ISO setting will determine how much grain is in your photo. You have to zoom in to see the grain, so here we go.
The first photo was taken at ISO 1200. The second was taken at ISO 200. In other words, the higher your ISO setting the more grain you will have in your image. When images have a lot of grain photographers often convert them into a black and white image because black and white images pull off high amounts of grain better than color images do.
So why would you ever shoot with high ISO? With the exception of adding grain for artistic effect, the only reason you will ever crank up your ISO is because you are shooting in a low light setting and you need to increase your ISO so you can get a properly exposed image that isn't blurry. That cause and effect will make more sense once we've gone over all of the lessons in the series, but it's important to know why and when ISO needs to be increased.
KEY CONCEPT: Low light (inside your home) = crank up your ISO
Plenty of light (outside in the daytime) = keep your ISO low
When I'm shooting inside my house my ISO is usually anywhere between 600-1600. Of course if you can find a big window to shoot by you won't need to raise the ISO nearly as much. When I am shooting in daylight I usually keep my ISO between 100-200.
Now if you would like the option of printing a nice enlargement of your image you should try to keep your ISO down around 200, but how often do we really need that? (Well unless you are a professional photographer). My point? Don't be afraid to raise your ISO, even up as high as 1600 if you need to. It's better to have a grainy image than a blurry one! And like I mentioned before, if it's too grainy, make it a black and white. I love black and white candids of my kids, they're my favorite.
Don't get me wrong there's no reason to raise your ISO higher than you need to, but sometimes it's necessary, especially inside most homes. This is part of the reason it's so much easier to shoot outdoors.
Start Thinking about How It Goes Together
The fourth and final lesson of this series will go into putting the three components together but I want you to start thinking about the relationship now. Put simply, it's a balancing game. Your camera needs a certain amount of light. ISO, shutter speed, and aperture setting all help determine how your camera will get the light it needs.
Lets go over a scenario real quick. You take a perfectly exposed picture. That means you have balanced your settings correctly. Then you decide that you want to change your aperture setting. No problem, you can do that. You will just need to then change either shutter speed or ISO to compensate for that change, because again, they have to stay balanced.
This will all make sense and you will see in the final lesson that your camera helps you make these choices (yes, even in manual mode) so you don't have to just start shooting in the dark. I just want you to start thinking about how they are all interrelated.
That triangle won't all make sense to you just yet, but it will once I'm done with you :)
Switch your camera into manual mode (scary, I know). Go to youtube and search "how to change the ISO on a [insert the name of your camera here]." Watch the video and experiment with changing your ISO. You don't actually need to take any pictures since we're still missing two pieces to the puzzle, I just want you to know how to change your ISO setting.
If you would rather you can also look up that information in your camera manual.
And that's it, ISO in a nutshell. I hope this made some sense. Please comment with any questions.