Great Pics Nikki!!!
Aperture value refers to the opening in the lens which "sees" the image and allows light to hit the film/chip of the camera. The apeture affects many things. If you hear someone refer to depth of field, thats a reference to the area in focus.
Travis likes to take macro photos (generally) with a good depth of field, meaning a larger area in focus. If someone wants a shallow depth of field, they want a smaller area in focus.
The aperture determines the depth of field. The only confusing part of that is that the numbers run backwards. Say your camera has aperture values, (or F-stops) that range from 2.8 all the way to 22. 2.8 will be the largest opening, and have the shallowest depth of field. Where as 22 will have the smallest opening and the deepest depth of field. This is generally where people get all confused.
Aperture also affects light and exposure time. If an image is overexposed it can be too white or hot...meaning that too much light has hit the image, this can be caused by using to large of an aperture, (f 2.8 for example) if an image is too dark it is generally caused by underexposure or not enough light hitting the film/chip. Such as using f 22. There are many ways to get around all of that under/over exposure stuff, but in order to tie all of this together I'm going to attempt to skip over it.
So we have f 2.8 which is a large opening and allows a lot of light to hit the image and gives up a shallow depth of field...but how do you remember that? Think fast.....
No really....fast is what you want to remember.
If a lens or a camera is refered to as being fast, it means it has a lens which will open really wide, like 2.8. Why does this mean fast? If the aperture allows in alot of light, (f 2.8) then the shutter doesnt have to open as long to get the right amount of light to properly expose the image..(think about taking wrasse pics here...if the shutter isnt open long, the camera doesnt have time to shake). So we have our fast aperture (f 2.8=lotsa light, quick exposure) but it sacrifices our depth of field...things are going to be out of focus behind our subject. Just like a fast car racing by that can hit 60 mph in 2.8 seconds, you're not gonna be able to get all the little details of it in focus. So fast lens = wide aperture, and shallow depth of field, and lots of light. So slow would be the exact opposite right? f 22= narrow aperture, less light so we have a longer exposure time to get the image right, but we have a greater depth of field which allows us to get all the little details of the image in focus...just like a car driving slowly past us taking 22 seconds to reach 60 mph.
Make sense?
I hope so, cause I know this can get confusing....
Travis and Wit, if you guys feel you can clarify this any more feel free to step in and explain.
Nick