In my first article we learned a little of the basics to get started with. In this article I'd like to expand and get a little more in depth. SHUTTER & APERTURE Aperture - simply stated, this is how you control your 'depth of field.' When you focus on a point or object, you put it in focus by means of the camera's autofocus system. How much focus or clairity you have in front and behind that object is your 'depth of field.' If everything behind your focus point is blurry, you have a shallow dof. If everything to the horizon behind your subject is clear, you have a large or deep dof. Aperture and dof are controlled by a set of butterflies in the lens of the camera. These butterflies open and close to control how much light enters the camera. The size of this opening is measured in F stops, or stops of light. If you look at either your led panel, or the bottom of your viewfinder, you see 2 sets of numbers. The one on the left is always your shutter speed. The one on the right, usually preceeded by an F, is always your aperture. So what does the number mean? Think of it this way, a small number means a small or very shallow dof, and conversly, a large number means a deep or large dof. When you do macro, or close up photo's of your tank, you want a smaller number so everything behind your subject gets thrown out of focus. This is especially important in aquarium photography as we have so much in our tanks, if we have everything in focus, we loose our main subject. Almost all cameras now have an auto macro setting, symbolized by a flower. This will automatically put your F stop at the smallest number, therefore shallowest dof possible. It also helps the camera focus closer than normal, which most lenses have a minimum focusing distance of around 5 feet. Let's stop here a moment and recall something from article 1. Macro does NOT mean you can put your lens directly on an object. That is microscope, not macro. Besides, how would light get in if your that close? For further instructions, see article 1. Most slr lenses common these days have a minimum aperture of around 3.5 or 4. This is usually good for most of our concerns here. Any lens that has a smaller mimimum aperture, 2.8, 1.8, etc. are refured to as "fast" lenses. These are usually the lenses you see photographers using at sports events that have an opening so big it looks like you could shove a bowling ball in it. They are called fast for a reason that has nothing to do with dof! Are you now Aperture has an equal partner in making a photograph. This partner is called shutter speed. You can not adjust one without effecting the other. As you shallow your dof by making the F number smaller, you are allowing more light through the lens. As you let more light in, you raise the shutter speed. In front of your fim, or digital sensor, there are a set of shutter curtains, similar to a set of blinds. When you press the button to take a picture, these blinds open and close at a preset rate. This is where the button you press got it's name, "shutter button." This rate of open and close is your shutter speed. This is the number on the left. When you see 120, 500, etc., these are parts of a second that the shutter is open. 120 would be 1/120th of a second. The faster the shutter speed, the less blur you have in your pictures. Always remember, you never want to shoot from hand with a shutter speed of less than 60. Anything less, you need to have the camera mounted on a tripod.