But that is really putting it way too simple. You will see what I mean when you get the cam and a nice bright lens.
Some lenses, especially the older ones, have an aperture ring. With most of these, you have to set the aperture on the lens; if you change it on the camera's dial it won't on the lens. With automatic lenses, which do not have an aperture ring, the number set in-camera will be electronically transmitted to the lens and then set.
Your camera has 4 "Exposure Modes" : "P" for Program, "M" for Manual, "S" for Shutter Priority and "A" for Aperture Priority.
In "P" your camera will select an aperture and shutter speed to give a correct exposure.
In "M" you can set the aperture and shutter speed any way you want.
In "S" you select a shutter speed and the camera will select a correct aperture.
In "A" you select an aperture and the camera will select a correct shutter speed.
Using "P" turns your DSLR into a glorified "point & shoot" since you have no control over the settings the camera chooses.
If you're shooting night scenes without flash then you'd use "M" so you can select both shutter speed and aperture to achieve the results you want. This requires a tripod to mount your camera on since shutter speeds are usually long - 2 seconds or more.
If you're shooting action - kids running and playing, sports or other fast moving subjects - then you'd choose "S" so you can keep the shutter speed high enough to stop the action.
If you're shooting nature or scenics you'd choose "A" since you'll want to control your aperture to give more or less Depth of Field (DOF)*. You must remember to check the shutter speed the camera selects to make sure it isn't too slow to hand-hold the camera.
A company called "The Magic Lantern" offers an instructional DVD for your camera. You should be able to find it at Circuit City or Amazon. It would, IMO, be very helpful.
Actual classes in photography would be the very best way to learn if any are available.
You might want to visit http://www.fotosharp.com and buy their "Day & Night Exposure Guide" if you plan on doing low-light, non-flash photography.
* DOF is loosely defined as the area in acceptable focus in front of and behind your subject. If you google "depth of field" you'll find numerous examples and discussions. If you go to http://www.expoimaging.net you can read about their ExpoAperture2. This is a circular chart showing the DOF for different focal lengths, apertures and sensor sizes.
There is no difference between the aperture in a film camera or in a digital camera. The aperture is the diameter of the adjustable iris that controls the amount of light passing through the lens and onto the film plane or digital sensor. An aperture is expressed as an f-stop, which is equal to Focal_Length / Aperture_Diameter, and is written: f/number. For example, if a lens has a focal length of 50mm - the 'normal' 35mm film camera lens - and the aperture diameter is 5mm, then the f-stop is 50/5 or f/10. If you know what f-stop a lens is set to, you can determine the physical diameter of the aperture. For example, with an aperture of f/11: - On a 50mm lens, the aperture is 4.55mm in diameter (50/11). - On a 100mm lens, the aperture is 9.09mm in diameter (100/11). - On a 20mm lens, the aperture is 1.82mm in diameter (20/11). F-stops are used because they are a standard way to express the amount of light passing through a lens. The amount of lens passing through a 50mm lens set to an aperture of f/11 is the same as the amount of light passing through a 300mm lens set to f/11. This is far simpler than measuring the diameter of the aperture to calculate relative levels of illumination.. |
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