BBRambles wrote:
I know it's probably inconveivable to you, an expert,that someone with a 5D wouldn't have a clue about what you speak but so it is. You're like a foreign language and that's what I'm wanting to learn; you're way ahead of me. As a traveler I take only animals and people - almost no landscape and yes I have a 100-400 but not the clarity of the f2 200 that I'm using for best possible. I do shoot in RAW. Learning aperture and fiddling with lightroom. Have an expert assist until I get it down pat. This is definitly not a once in a life time -- it's my 9th African safari and have done 5 in India. THANK YOU so much for your reply! I will print it and keep it on my the horizon as I try to figure this out. Too bad you can't see the elephant head I've had printed at 56" X 37". A WOW! Going for perfection! Barbara
I know it's probably inconveivable to you, an expe... (
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Barbara,
sorry... i assumed someone who'd spent over $6000 on a 5D2 and fast lenses probably understood the basics of aperture and shutter priority.
first, some basics. aperture is the term used to denote the size of the lens opening. the aperture controls how much light the lens lets in for any given shutter speed. a larger aperture lets in more light, and a smaller admits less.
your 200mm lens has settings from f/2 (a very large opening) to f/32 (a very small opening). at f/2, you can shoot photos in very dim light without a flash, but the depth of field (the portion of the photo that's in sharp focus) will be small. with a small aperture, your photo will be sharp from front to back, but you'll need a lot more light to get a correct exposure.
the shutter speed tells you how long the shutter stays open. a fast shutter, say 1/1000, means the shutter only opens for 1/1000 of a second - not very long, so not a lot of time for light to reach the sensor. that means you can only use fast shutter speeds in bright light, but a fast shutter will stop motion, so it's desirable for photographing moving subjects. a slow shutter, like 1/60 of a second, means the shutter stays open longer, so that more light reaches the sensor. this is useful when the light's not as bright and the camera needs more time to gather enough light for a proper exposure.
the ISO setting controls the sensitivity of the sensor. a low ISO setting, like 100, means the sensor isn't very sensitive to light, so it needs more light (a slower shutter or a wider aperture, or both) for a good exposure. a higher ISO setting means the sensor is more sensitive, and doesn't need to be exposed for as long to a capture enough light. when the light is bright, you can use a lower ISO setting and still get enough light. in dim light, you'll want a higher ISO setting so that the sensor will collect enough light to make a good picture.
as you can see, aperture, shutter speed and ISO are all inter-related, and you have to understand all three in order to make the most of your camera's capabilities.
now for operating modes...
in aperture, or Av mode, you set the aperture, or size of the opening in the lens, which controls depth of field, or how much of the image will be in focus. a small aperture makes most of the image, from close to far, in focus. a wider opening (smaller f-number) makes only the subject clear, and in some cases, not even that. when you shoot in aperture mode, you select the aperture, and the camera automatically selects a shutter speed that will give you a proper exposure.
in shutter priority (Tv) mode, you select the shutter speed you want, to control how motion is captured, and the camera chooses the aperture to provide a good exposure. for moving subjects, like a running antelope, you might want a fairly fast shutter, like 1/500 or 1/1000, to freeze the animal's movement and avoid blur. for birds in flight, you'll need a minimum of 1/1000, maybe faster.
in manual mode (M), you set both aperture and shutter speed, and the camera will shoot what you've told it to, whether it's properly exposed or not. you won't be using manual any time soon, most likely, but it's still good to know what it does.
of course, as you know, in auto, or 'program' mode, the camera chooses everything, and all you do is compose and press the shutter.
i strongly suggest you invest some time before your trip in reading about how exposure works, and the relationship between aperture, shutter speed, and ISO settings. your images will get better, and you'll open up a whole new world of photo possibilities. read the manual that came with your camera. read online articles on camera basics. learn as much as you can before you go, so that you'll be better able to take the photos you want.