The new consumer-level digital cameras are so easy to use, they confuse me. They have so many settings on the control dial that anyone can get a picture-- a usable picture, not necessarily the picture you're looking for.
All those individual icons on the dial help control settings to a degree.
I'm in the process of helping a friend learn to use her new Nikon D3000. She wanted better pictures than her point-and-shoot was giving her, so like many people, she decided the only way to do that is to purchase a new, expensive digital SLR.
Well, not exactly. With P&S, you don't worry about depth of field, shutter speeds, ISO. Just press the button, and they get surprisingly good photos. For closeups, they are hard to beat-- no special closeup lenses, extension tubes, bellows, etc.
So, she has spent the last six months learning about all the buttons on her SLR. One of the biggest advantages of an SLR is being able to control the settings. But you must understand how f-stops, shutter speeds and ISO all relate to each other.
The photos above show depth of field, and how controlling the aperture (lens opening) can create a totally different photo. At left the lens is wide open, in this case f2.8. At right the f-stop is f22. The pink forget-me-nots are lost at right, but stand out a bit better in a sea of blue at left.
F-stops control what is in focus beyond the single subject you've already focused on. The larger the number, the more in focus and the smaller the hole in the lens. Think of it as squinting-- when your eye is closed down, you sometimes see more clearly. Shutter speeds control what action is stopped. The higher the bottom number (in 1/1000, 1/4000 for example), the more is stopped. Most cameras display only the bottom number, or reciprocal. So 1/125 for example, is the same as 125.
The hard part to understand is that if your perfect exposure is f2.8, 125 and 200 ISO, changing any of those three variables would necessitate changing at least one of the others.
Closing down the lens to get more in focus means you have to let more light onto the sensor, and that's where shutter speed and ISO comes in. Slow the shutter speed if possible, or raise the ISO (increase its sensitivity). For every stop (2.8 to 4, for example) you must slow the shutter equally (125 to 60, for example). Or raise the ISO (200 to 400, for example).
Try this-- imagine that your camera says the correct exposure is f2.8 at 500 second at 100 ISO. But you want to shoot at f22, to get a lot more in focus but severely limited the amount of light through the lens. From 2.8 to 22 is six stops. You'll have to slow the shutter six stops as well to let the same amount of light to hit the sensor (film). Six stops slower is 1/8 second. That's very slow, it won't stop much movement, and you'll probably shake the camera at that speed.
Now, by setting the camera on A for aperture priority the shutter speed will be set for you, once you set the lens. But shooting closeups or long shots with a telephoto lens will probably not work at 1/8. Too shaky. You can use a tripod, or steady the camera on a tree or post.
Or, boost the ISO. Boosting the ISO from 100 to 800 is three stops (100, 200, 400, to 800). Now your shutter speed is 60. For closeups, that'll probably be OK unless something's moving in the picture. It's still 'iffy' with a telephoto where the general rule of thumb is never hand-hold a lens with a shutter speed slower than the reciprocal of the focal length.
In other words, if you use a 300mm lens, the shutter speed should not be slower than 1/300. A 24? Nothing slower than 1/24. Of course, this rule depends on your ability to hold still, the whether the subject is moving, etc.
Remember if you set the camera at "A" for aperture priority, it'll the shutter speed for you. Just don't let it go too slow. Set the camera at "S" for shutter priority, and it'll set the aperture (lens opening) for you.
Decide what kind of picture you want, and set S (stop action) or A (depth of field and focus) first. You can play with settings from there.
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