Sorry this took me so long to get to! (I'll try to get the third post (which will be about ISO) put up without letting as much time pass.) If you haven't read my first post, then go here and check it out: http://hipgirlclips.com/forums/pictu...ure-bokeh.html
This post is going to cover the concept that is probably the one everyone has heard of, or already has an idea about. Shutter speed is how fast the little hole in your camera opens and closes when it captures the image. The slower the shutter speed, the longer that hole stays open. This means more light is let in, and the higher chance that moving objects will blur, or past a certain point, the whole picture will be blurry from "camera shake", unless you are using a tripod. (I'll get more into that in a minute.)
Shutter speed is mostly talked about in fractions of a second. I flipped on my camera just now, and it said "200" for shutter speed. What this actually means, is that the shutter will be open for 1/200th of a second. If you remember fractions from elementary school, you'll remember that the higher that bottom number, the smaller the fraction, ergo, the faster the shutter speed.
For those of you who have cameras where you can choose shutter speeds, you may notice that at some point, the number will start to have a quote sign past it, like 1" That designates that you have moved beyond fractions and are now using a full second for your shutter speed. Cameras differ on what shutter speeds they go to. (Mine will go to 30 seconds, but it also has a bulb function, which is used in night photography and star pictures, but I won't get into that right now.)
Camera shake is what happens naturally when you hold your camera. It's the little tremors and twitches your hands do while holding a camera. Usually they are so small you don't see them. However, beyond a certain point, they will start to affect your pictures. The general rule of thumb is that if you are going to be hand holding your camera, you want to use a shutter speed of 1/60 or faster. I have been working on training myself to be able to hand hold at slower shutter speeds, and can get down to 1/10 sometimes with no noticeable blur to my photos, but it's taken me years to get to that point. (and it doesn't always work.)
Aperture and shutter speed are intimately related and depend on each other. Sometimes you want a picture with a nice wide aperture, so you can get some lovely bokeh in the background. To keep your picture from turning out too bright (overexposed) you'll need to use a faster shutter speed. Other times you may have a picture where you want everything to the horizon in focus, so you'll want to use a smaller aperture. That smaller hole will mean you need to use a slower shutter speed to let in enough light, to keep the image from being too dark. (underexposed) But, slower shutter speed can mean camera shake, and moving objects in your picture, such as small children, will blur.
Not all blur is bad though. There are times where you may want to show movement in your photo, and blur can be a great way to do that. I'm attaching two pictures as an example. I took them in the Smoky mountains at a stream. The first picture was fine, but I decided that I wanted to show the movement of the water better, so I used a slower shutter speed. In this case, my shutter speed took precedence, so I had to adjust my aperture accordingly and make it smaller. If I hadn't done that, the picture would have turned out overexposed. An opposite example would be if, say, I had wanted to snap a picture of a baseball in midair after being thrown. That would take a fast shutter speed, and to compensate, I'd need to use a larger aperture (remember, smaller number!) to keep the picture from being too dark.
And that is shutter speed! As always, if anyone has any questions about anything, let me know! I'd be happy to help.
See below for example pictures, and the settings were these:
First picture: Shutter speed 1/80 (faster) Aperture f 4.5 (bigger)
Second picture: Shutter speed 1/10 (slower) Aperture f 11 (smaller)
(You might notice that the rocks in the second picture are a little fuzzier than the first picture, as I did have some camera shake happen. I think it doesn't detract from the picture too much in this instance though, and I love the effect I got from the water.)