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Because you said you're having trouble selecting the correct f/stop, I'd like to think you're working in Manual for the class. If that's true, good. And, if so and the day is sunny, start with the Sunny 16 Rule. Set your aperture on f/16 and your shutter speed at the reciprocal of the camera's ISO setting [or ISO of the film] you're using. As actual weather conditions vary, say from bright sun to cloudy, OPEN the aperture by changing the f-number to f/11 or f/8. If it's sunny but your in shade and walk into ab n open area, you may have to close the aperture to say f/16. Note, the f-number is the ratio of the focal length of your lens to the diameter of its diaphragm. The "speed" of the lens is this same ratio, when the aperture is wide open, the focal length is at its maximum and the lens is focused at infinity. The LARGER the f/stop, the more light is allowed to pass; the SMALLER the f-stop, the less light is allowed to pass. The LARGER the f-stop, the less Depth of Field [distance of acceptable focus] is achieved; the SMALLER the aperture, the greater the Depth of Field. If you're using an automatic camera in an Auto Mode, do not use the AUTO Setting. If you do, with most cameras you'll find yourself with simply a point and shoot camera [taking pictures at some factory determined exposure such as f/9 at 1/40th sec.] As a minimum use the Program Mode, in which the camera will make certain exposure adjustments "on its own." I do recommend that you use a Creative Mode, preferably Aperture Priority. Set the aperture to f/8 [as a starting point;] the camera will select the appropriate shutter speed according to its EV program algorithm. All you'll need to watch is whether the selected shutter speed is reasonble - you should be able to hand hold your camera at a shutter speed equal to 1/(lens focal length.) If the selected shutter speed is less than this value, you'll need to open the aperture, change the ISO setting or use a tripod.
April 29, 2008
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