I have a digital SLR camera. Love it. But I need some input.
I love my 18-200 lens, but it's so darn SLOW. I tried to take pictures of Angel (my wife) doing some leaps (she's a dancer) the other day, and it was almost an exercise in futility.
Anybody know of a good site to find some tutorials on using aperture/shutter to full advantage, or preferably a book? I've been using Ken Rockwell's recommended settings on my D40 for a while now, and focusing on framing in my shots, but I'd like to be able to play with some different f-stop settings and shutter speeds now to convey some different things with the shots.
You're unfortunately at the point where physics limits the art of what you're trying to do. The chemicals on the film or in the digital "eye" of the camera need a certain amount of light to function properly, which leaves you with really just a few choices. You can change to a faster "eye" (or change film to higher speed film), use a larger aperture lens, add more light to the subject, or make sure that you focus manually to eliminate any problems with autofocus.
(I've taken a lot of good pictures in dim light with manual focus, including one 2-3 second handheld exposure of Mt. Rushmore at dusk....OK that one would have benefited from a tripod!)
I have a Canon DSLR so I'm not real familiar with Nikon.
My camera has a setting where you set the shutter speed and the aperture adjusts automatically to get the right exposure. Set the shutter speed as fast as you can so the action shots don't look blurred. If you can't do that with your camera, then you'll have to set a fast shutter speed and mess with the aperture until you get the right exposure.
If you're in low light, adjust the ISO as high as you can, 1600 or 3200. This will make the sensor sensitive to light and hopefully accommodate a fast shutter speed.
You also might need to move the camera along with your wife to reduce blur. I think that's called panning.
I'm kind of new at this too. It's tons of fun. Good Luck!