What is Aperture? Intro to lesson.
11-09-2008, 11:27 AM
This is a very common question among novices and amateurs alike. Isn't it about time someone puts it in simpleton terms anyone can understand?
OK, but how does the aperture size affect my photos?
Again, a very common question. Aperture will affect your photos in two ways:
-How bright or dark your photo is-
-How shallow or deep your DOF (Depth of Field) is (we will not cover that in this lesson)-
Let's talk about how it affects the brightness of your shots. Aperture rates are shown in units called 'ƒ-numbers'. What the purpose of the ƒ-number is is to show us the diameter of the 'diaphragm' in the lens, which means the opening in the back of the lens. The diaphragm allows the light into the camera's sensor or film, depending on if you use a film or digital camera. This creates the image. The higher the ƒ-number, the less light allowed onto the sensor or film, thus determining the brightness of the photo. Yes, the higher the lower. It is a confusing system, yes, but just don't let it mess you up. The standard aperture range on an SLR camera (digital or film) is ƒ/1.4, the highest aperture, to the lowest aperture, ƒ/8. The settings in between ƒ/1.4 and ƒ/8, known as ƒ-stops, are usually ƒ/2, ƒ/2.8, ƒ/4, ƒ/5.6. Aperture alone does not determine how the photo will come out, though. The other element is shutter speed, meaning how quickly the photograph is taken... and how much light is allowed in. But I thought aperture controlled that? It does. Lets get into detail (We can't explain aperture without talking about shutter speed!)
Shutter Speed In Detail:
Shutter speed dictates how long the shutter is open, which in turn means how much light is in the picture (how bright it is). Aperture determines the brightness of the light that comes in. You may need to read this paragraph over a few times, and think about it for it to make sense. The reason we need to talk about shutter speed in a lesson about aperture is simple: there is no avoiding them both when taking a photo manually. So, lets get started.
What's my shutter speed gonna do?
Your shutter speed will determine how long your shutter will stay open. Most cameras have a maximum shutter speed of anywhere from 15 seconds up to 30 seconds. You have probably heard of the term "long exposure" before. A long exposure is normally considered a shutter speed of 1/50 of a second, meaning half a second. Some shutter speeds considered long exposures are 1/60, 1", 3", 5", etc. If you want a sharp image, you need a tripod. To get an exposure above the preset setting on your camera's maximum setting (usually 15"-30") you will need to have a "bulb" mode. For a bulb mode, you will need a cable release, which can be set in the cable release socket on a film SLR or the hotshoe terminal on a digital SLR. You can have an exposure for however long your heart desires. This is especially useful when you want to do photos like star trails, because you can't get star trails with a 3" exposure. All this talk about long exposures, and no fast shutter speed discussion? Well lets talk about that now. Anything below 1/50 is considered a fast shutter speed. Examples of fast shutter speeds are 1/40, 1/1000, 1/400, and 1/2000. Most normal SLR's fastest shutter speed is 1/2000. If you took a photo at 1/2000 then the shutter would be open for 1/2000 of a second, allowing 1/2000's worth of light in. You will have a somewhat dark image at this speed, because 1/2000 will not allow as much light in as a longer would, such as 1" would. Here is an easy way to remember that: the higher the exposure, the more light that can enter the sensor or film, the shorter the speed, the less light. But, the quicker the shutter speed the quicker the picture is taken, meaning that moving subjects can be easily captured.
I hope this helps some of you!