Turn Off Vibration Reduction (or IS)
The big rage in digital lenses these days are the Vibration Reduction (VR) lens from Nikon and the Image Stabilization (IS) lens from Canon, which help you get sharper images while hand-holding your camera in low-light situations. Basically, they let you hand-hold in more low-light situations by stabilizing the movement of your lens when your shutter is open longer, and honestly, they work wonders for those instances where you can't work on a tripod (like weddings, some sporting events, when you're shooting in a city, or just places where they simply won't let you set up a tripod). If you're in one of those situations, I highly recommend these VR or IS lenses, but depending on which one you use, there are some rules about when you should turn them off. For example, we'll start with Nikon. If you are shooting on a tripod with a Nikon VR lens, to get sharper images turn the VR feature off (you do this right on the lens itself by turning the VR switch to the Off position). The non-technical explanation why is, these VR lenses look for vibration. If they don't find any, they'll go looking for it, and that looking for vibration when there is absolutely none can cause (you guessed it) some small vibration. So just follow this simple rule: When you're hand-holding, turn VR or IS on. When you're shooting on a tripod, for the sharpest images possible, turn VR or IS off. Now, there are some Nikon VR lenses and some older Canon IS lenses that can be used on a tripod with VR or IS turned on. So, be sure to check the documentation that came with your VR or IS lens to see if yours needs to be turned off.