I wrote this for a friend who has a new camera. When I offered to help her learn things, she said that she is still confused about the basics. She says she has done some reading but… So, here’s me trying to use my writing skills to give a plain explanation of aperature and shutter speed, and how they work with each other. I recommend printing this out so you can have it with you as you do a bunch of shots just for the sake of learning about your camera. Learning to use your camera can be frustrating, but remember that when you were learning to drive you felt all kinds of confusion and uncertainty… it takes time to feel “normal”, ’kay? :) _________________
Key Concept: With every shot we do, we want to let the perfect amount of light into the camera.* The problem is that the amount of light we are dealing with is always different, so we have to keep making adjustments. Lucky us, the camera has two ways to affect the amount of light in. The APERATURE – This is the hole inside the lens. If you take one of your lenses and look through it you will see a hole… the size of that hole changes when you adjust your “Aperature setting”. I don’t even know why we have the numbers that are always used, but the actual numbers don’t matter. The thing to remember is: High numbers means more restriction… or High is hard to get enough light in; High is Hard, Low is Lots! This is why we usually end up with high aperature numbers outside; we HAVE TO restrict how much of that light is getting in. The SHUTTER SPEED – this is the amount of time that the camera allows light to enter. Obviously more light can enter in 1 second than in 1/60th of a second. Our cameras are amazing in how fast they can open and close the shutter… yours might be able to do something like 1/4000th of a second. Cool, eh? …hey, don’t sidetrack me! :)
Key Concept: The aperature and the shutter speed are designed to work connected to each other.* Whenever we shoot with the perfect settings, we get a nice result. Your camera is designed to help you achieve that. For the novice who lets the camera make all the decisions by setting the camera on “auto”, the camera reads how much light there is, then chooses a shutter speed and an aperature that combine for what it thinks is right. You and I want and need more control than that, so… Setting “A” – “APERATURE PRIORITY”- This is the one I use the most. It means that when I turn my adjustment wheel, I am changing the size of the hole in the lens… the camera magically adjusts the shutter speed to match it. PROBLEM: It may be forced to have such a slow shutter speed, I will easily have blurry pictures because either I move or the subject moves. Setting “S” – “SHUTTER PRIORITY”- This option lets me choose which shutter speed I will use, and the camera will magically adjust the aperature for me. PROBLEM: the lens is limited in how big or small it can make that hole, so I might not be able to use any ol’ shutter speed I want… it depends on how much light is available.
Key Concept: The aperature and shutter speed ALWAYS affect each other.* When your camera indicates that you have your settings right, it is only one of several combinations of settings that are right. Let’s use the example of a wedding couple walking down the stairs out of the church on a sunny day. You are working in the "A"setting, (aperature priority). Your light indicator says you have the settings perfect. Let’s say you read the numbers “30” and “22” on your display. You know that 1/30th of a second is pretty slow, and you’d rather not have them blurred wherever there’s movement, so you want to make the shutter speed faster. You need to open the aperature more to let more light in, which causes the camera to make the shutter faster to keep out that extra light you are letting in. You have arranged for the couple to stop when they reach the bottom of the stairs, so the fast shutter speed is no longer an issue, but you would like to make this shot more of a portrait shot by having the background as blurry as possible. To achieve that effect you want the shortest-possible depth of field which is achieved by having your aperature wide open. When you make that change, you will find that the camera makes the shutter speed reeeeeeeeeeeeally fast in order to shut out most of the light, getting back to a perfect combination. You go back up the steps of the church to get a wide-angle shot of the 200 people who are mingling in front of you. Now your main concern is to have a large depth of field. This is achieved with a small aperature, the high numbers. When you make the change to your highest-possible aperature number, you will notice that the shutter speed has been dramatically reduced, much slower, to let in more light after you restricted the size of the hole so much. If you watch the numbers change on your display, you will see that as you make the aperature (hole) smaller, the shutter will get slower to make up for it.
I recommend that you practise with, to become used to, the “A” setting. Most of what we shoot is not moving very fast, so the depth of field is the more important consideration. _____ Now, having written all of that without really checking to ensure that it was complete, PLEASE let me know where the spots are that you are unsure about… if I skipped or contradicted myself… whatever. I sure hope I haven’t merely added to your confusion!!